Editor’s Office and Advertiser Information:
Florida Water Resources Journal 1402 Emerald Lakes Drive Clermont, FL 34711 Phone: 352-241-6006 • Fax: 352-241-6007 Email: Editorial, editor@fwrj.com Display and Classified Advertising, ads@fwrj.com
Business Office:
News and Features
P.O. Box 745, Windermere, FL 34786-0745 Web: http://www.fwrj.com General Manager:
Michael Delaney
Editor:
Rick Harmon
Graphic Design Manager:
Patrick Delaney
Mailing Coordinator:
Buena Vista Publishing
4 Holistic Look at Optimizing Biofilters and the Water Treatment Process— Jennifer Nyfennegger, Jess Brown, Kara Scheitlin, and Chance Lauderdale
57 Florida Team Wins WEF Student Design Competition
Published by BUENA VISTA PUBLISHING for Florida Water Resources Journal, Inc. President: Richard Anderson (FSAWWA) Peace River/Manasota Regional Water Supply Authority Vice President: Greg Chomic (FWEA) Heyward Incorporated Treasurer: Rim Bishop (FWPCOA) Seacoast Utility Authority Secretary: Holly Hanson (At Large) ILEX Services Inc., Orlando
Technical Articles 10 Construction Manager At-Risk Implementation for a Water Treatment Plant Granular Activated Carbon Filtration Project—Edward Alan Ambler, E. Devan Henderson, and Matt Peterson
24 Disinfection Byproduct Formation Potential Reduction and Hydrogen Sulfide Treatment Using Ozone—Greg Taylor, Charles DiGerlando, and Christopher R. Schulz 34 Effects of Backwash Water and Chemical Addition on Biofiltration—
Moving? The Post Office will not forward your magazine. Do not count on getting the Journal unless you notify us directly of address changes by the 15th of the month preceding the month of issue. Please do not telephone address changes. Email changes to changes@fwrj.com, fax to 352-241-6007, or mail to Florida Water Resources Journal, 1402 Emerald Lakes Drive, Clermont, FL 34711
Membership Questions FSAWWA: Casey Cumiskey – 407-957-8447 or fsawwa.casey@gmail.com FWEA: Karen Wallace, Executive Manager – 407-574-3318 FWPCOA: Darin Bishop – 561-840-0340
Hongxia Lei, Dustin W. Bales, and Maya A. Trotz
46 Treatment of Organic-Laden Surface Water for Total Organic Carbon— Steven J. Duranceau
Education and Training 15 32 41 45
Training Questions FSAWWA: Donna Metherall – 407-957-8443 or fsawwa.donna@gmail.com FWPCOA: Shirley Reaves – 321-383-9690
For Other Information DEP Operator Certification: Ron McCulley – 850-245-7500 FSAWWA: Peggy Guingona – 407-957-8448 Florida Water Resources Conference: 888-328-8448 FWPCOA Operators Helping Operators: John Lang – 772-559-0722, e-mail – oho@fwpcoa.org FWEA: Karen Wallace, Executive Manager – 407-574-3318
Websites Florida Water Resources Journal: www.fwrj.com FWPCOA: www.fwpcoa.org FSAWWA: www.fsawwa.org FWEA: www.fwea.org and www.fweauc.org Florida Water Resources Conference: www.fwrc.org Throughout this issue trademark names are used. Rather than place a trademark symbol in every occurrence of a trademarked name, we state we are using the names only in an editorial fashion, and to the benefit of the trademark owner, with no intention of infringement of the trademark. None of the material in this publication necessarily reflects the opinions of the sponsoring organizations. All correspondence received is the property of the Florida Water Resources Journal and is subject to editing. Names are withheld in published letters only for extraordinary reasons. Authors agree to indemnify, defend and hold harmless the Florida Water Resources Journal Inc. (FWRJ), its officers, affiliates, directors, advisors, members, representatives, and agents from any and all losses, expenses, third-party claims, liability, damages and costs (including, but not limited to, attorneys’ fees) arising from authors’ infringement of any intellectual property, copyright or trademark, or other right of any person, as applicable under the laws of the State of Florida.
FSAWWA Conference TREEO Center Training FWPCOA Training Calendar CEU Challenge
Columns 20 21 22 32 54 55
Certification Boulevard—Roy Pelletier FSAWWA Speaking Out—Carl R. Larrabee Jr. Technology Spotlight—Roger K. Noack C Factor—Jeff Poteet FWEA Focus—Kart Vaith and Lisa Prieto Reader Profile—Jeffrey Nash
Departments 55 58 61 63
New Products Service Directories Classifieds Display Advertiser Index
Volume 66
ON THE COVER: A water treatment clarifier at the North Springs Improvement District in Coral Springs. (photo: Michael Gardner)
November 2014
Number 11
Florida Water Resources Journal, USPS 069-770, ISSN 0896-1794, is published monthly by Florida Water Resources Journal, Inc., 1402 Emerald Lakes Drive, Clermont, FL 34711, on behalf of the Florida Water & Pollution Control Operator’s Association, Inc.; Florida Section, American Water Works Association; and the Florida Water Environment Association. Members of all three associations receive the publication as a service of their association; $6 of membership dues support the Journal. Subscriptions are otherwise available within the U.S. for $24 per year. Periodicals postage paid at Clermont, FL and additional offices.
POSTMASTER: send address changes to Florida Water Resources Journal, 1402 Emerald Lakes Drive, Clermont, FL 34711
Florida Water Resources Journal • November 2014
3
Holistic Look at Optimizing Biofilters and the Water Treatment Process Jennifer Nyfennegger, Jess Brown, Kara Scheitlin, and Chance Lauderdale Biofiltration for drinking water applications can offer many advantages with respect to operation and water quality. Biofilters are commonly used for particulate removal (like conventional granular media filters), but can also simultaneously remove multiple organic and inorganic compounds. For example, inorganic constituents such as manganese and iron are commonly removed by biofiltration. Removal of organic compounds can decrease dissolved/biodegradable organic carbon (disinfection byproduct precursors), color, tasteand-odor compounds, and trace organics, such as endocrine disruptors and pharmaceuticals. When filter media is not exposed to chlorine/chloramines, the microbiology naturally develops on the filter media. By relying on this natural process to remove and, in the case of organic compounds, destroy contaminants, biofiltration offers a “green” technology with low chemical and energy requirements. Even with these numerous benefits, drinking water biofilters can be prone to operational challenges. This article discusses these limitations and presents biofiltration control tools for preventing or overcoming them. Pilot results from the optimization of these “Engineered Biofiltration” strategies are discussed, as well as opportunities for the holistic optimization of the water treatment process.
Potential Biofiltration Challenges As water is treated through biofilters, biofilm growth and accumulation of solids restrict flow and cause headloss across the filter bed. Biofilters are routinely taken off line for backwashing to manage headloss buildup and maintain uniform hydraulic flow. The biofilm is predominately comprised of extracellular polymeric substances (EPS), which can occupy a thousand times more void space than the microorganisms (Mauclaire et al, 2004). The EPS can be both beneficial and detrimental within the biofilter. As listed in Table 1, benefits of microbial EPS include adhesion and protection for the microorganisms; negative impacts include clogging of biofilter media and underdrains. This can translate to operational challenges such as high headloss, decreased filter productivity, and underdrain failure. Back-
4
washing alone is not always sufficient to remove biological fouling, restore clean-bed headloss, and prevent underdrain failures. The addition of chlorine and chloramines to the biofilter is a common tool for biofilm control, but at the detriment of biological activity and associated water quality performance. Pilot studies spanning two Water Research Foundation projects focused on overcoming typical biofiltration challenges by implementing two Engineered Biofiltration strategies: nutrient enhancement and hydrogen peroxide (H2O2) supplementation.
Strategies to Overcome Biofiltration Challenges Nutrient Enhancement - Effective biofiltration for aerobic drinking water treatment requires a nutritional balance of oxygen, nutrients, and biodegradable organic carbon. Under these conditions, microorganisms break down organic carbon into carbon dioxide and water end products, the microbial population grows, and microorganisms produce EPS. Coagulation, flocculation, and sedimentation processes upstream of biofilters typically lead to nutrient-limited conditions in the feed water. These limitations may stress bacteria, causing them to secrete large quantities of EPS. This overproduction of EPS can negatively impact hydraulic operation of the biofilters, as discussed. Implementation of a balanced nutritional ratio reduces biological stress, thereby minimizing EPS production and associated operational concerns. Peroxide Supplementation - The H2O2, when added at low concentration, can oxidize and remove EPS and inactive biomass. Peroxide added to the biofilter feed water works to lower EPS concentrations throughout the filter run. The H2O2 applied at low doses does not harm active biomass, and therefore allows the biofilter to continue operating without degradation to water
November 2014 • Florida Water Resources Journal
quality. When underdrain clogging is a concern, H2O2 can be added to the backwash source.
Optimization of Engineered Biofiltration Strategies Materials and Methods The pilot study identifying the biofilter enhancement strategies are described in Lauderdale et al (2011). Follow-up studies were conducted at Tampa Bay Water and Dallas Water Utilities to optimize the Engineered Biofiltration strategies (Lauderdale et al, 2014). At each location, a pilot biofiltration skid (Intuitech; Salt Lake City, Utah) included four dedicated influent feed pumps, four biofilter columns (6-in. diameter), peristaltic pumps for feeding chemicals and spiking contaminants, and a backwash system. Three of the four columns at both pilot sites were packed with sand and granular activated carbon (GAC), and the fourth with sand and anthracite. Media heights were similar to the host site’s full-scale filters (6-in. sand and 48-in. media for Tampa Bay; 12-in. sand and 24-in. media for Dallas). Each filter was independently operated with automatic flow control and configured for on-line or standby operation. Hydraulic loading rates during testing ranged from 2.5 to 4.0 gal per minute per sq ft (gpm/ft2). A break tank was used to store and provide the backwash supply water. Pilot backwash protocols (including air scour, high-rate, and low-rate backwash steps) were similar to those for the host site’s full-scale filters. Control and monitoring of the pilot skid were provided through a skid-mounted programmable logic controller. Headloss, filter flow, and effluent turbidity from each biofilter were continuously monitored and logged every 10 minutes. In addition, water quality samples were collected two times per week from the pilot influent and effluent of each Continued on page 6
Table 1. Positive and Negative Impacts of Biofilm Extracellular Polymeric Substances on Biofilter Operation
Continued from page 4 biofilter column. The samples were analyzed for water quality parameters such as organic carbon (dissolved and total), color, 2methylisoborneol (MIB), geosmin, orthophosphate, ammonia, manganese, and iron in accordance with the appropriate methods from the U.S. Environmental Protection Agency (EPA) or Standard Methods for the Examination of Water and Wastewater. Nutrient Enhancement Lauderdale et al (2011) showed that lowdose phosphorus supplementation (0.02 mg/L) to the biofilter feed water reduced headloss by 15 percent over the course of a given filter run. This decrease in terminal headloss translates to an increase in the filter run time to reach a given headloss trigger for backwashing. The study also showed that nutrient enhancement increased the removal of dissolved organic carbon (DOC) across the biofilter. These studies were conducted using settled water (pH = 7) from upstream ozonation and alum coagulation processes as the biofilter feed water. Subsequent pilot studies showed that biofilters receiving settled water from upstream processes using ferric as a coagulant did not show hydraulic improvements with PO4-P supplementation alone. Water quality modeling suggested that dosed PO4-P adsorbed to ferric hydroxide carryover in the biofilter feed at ambient pH. Increasing the feed pH results in more dissolved (bioavailable) phosphorus by changing the surface charge of the carryover floc to repel (thus inhibiting adsorption of) the negatively charged PO4-P molecules. When the biofilter feed water pH was increased to between 8 and 8.5, hydraulic performance improved. Terminal headloss of the nutrient- and pH-enhanced biofilter decreased by >18 percent relative to the control biofilter with no degradation in effluent water quality. Thus, the type of upstream coagulant and biofilter feed pH are important factors for successful implementation of the nutrient-enhancement strategy.
Hydrogen Peroxide Supplementation Peroxide addition to the biofilter feed water has resulted in improved hydraulic performance at pilots in Florida and Texas (Nyfennegger et al, 2013; Lauderdale et al, 2011). The optimal dose was site specific, and varied between 0.1 and 1 mg/L. This suggests that plant-by-plant optimization may be necessary to achieve an optimal use of this strategy. A backwash study compared backwash efficacy using the backwash water with and without 10 mg/L of H2O2. Before each backwash study, the underdrain fouling was promoted by adding 10 mg/L of ethanol to the biofilter (6 in. above the underdrain) during normal filter operation. The measured pressure differential across the underdrain increased to approximately 10 times the baseline level prior to each underdrain fouling mitigation test. Once this pressure differential was achieved, backwashes were performed at 24hour intervals without chemical mitigation until clean-bed underdrain differential pressures decreased and remained steady. This process (i.e., underdrain clogging followed by suspension of ethanol dosing and manual initiation of a backwash every 24 hours) was repeated with 10 mg/L peroxide dosed to the backwash water. Differential pressure measurements during the high-rate backwash step were 50 in. and 35 in. for the unenhanced backwash and peroxide-enhanced backwash, respectively, indicating that the peroxide enhancement helped to mitigate underdrain fouling. In addition, clean-bed underdrain pressures were slightly lower after the first enhanced backwash (6.8 in.) versus unenhanced backwash (7.7 in.). Differential pressure remained lower for the enhanced backwash protocol during subsequent backwashes. When implementing H2O2 supplementation, the type of biofilter support media should be considered. Microbial activity of anthracite biofilters decreased during periods of peroxide addition (0.5 to 2 mg/L). However, microbial activity of the GAC biofilters was
Figure 1. Treatment optimization may yield cost savings and water quality benefits across multiple processes.
6
November 2014 • Florida Water Resources Journal
steady before and during H2O2 testing, which spanned the course of a year. Upstream Coagulant Dose Pilot-scale-enhanced coagulation pretreatment optimization was performed concurrently with the biofiltration pilot at the Dallas pilot site. Using coagulant doses of 60 mg/L and 30 mg/L (as Fe2(SO4)3*9H2O), results showed that the total DOC removal through the coagulation and biofiltration processes was similar at the two doses tested. At the lower ferric dose, a higher percentage of DOC was removed through biofiltration, which made up for the lower percent DOC removal observed across the coagulation process. This demonstrates synergy between the coagulation and biofiltration processes, and presents a significant opportunity for cost savings on chemical costs without compromising water quality. At the host facility’s annual average design flow of 77 mil gal per day (mgd), the decrease in coagulant dose will result in an annual savings of $961,000. Media Type Anthracite-based biofiltration performance for key water quality parameters (e.g., DOC, geosmin) was inferior to performance of GAC biofilters under control and enhanced conditions. However, site-specific goals should be considered when choosing between anthracite and GAC as a biofilter support media. When the performance of anthracite biofilters meets a site’s goals, the selection of anthracite can result in significant cost savings. Although more expensive, GAC may also be a more robust support media for biofilters and offer more reliable performance during process upsets.
Optimizing the Water Treatment Process Optimized biofiltration may yield cost savings and water quality benefits across multiple processes. These are illustrated in Figure 1 and described here: 1. Improved taste and odor removal (e.g., MIB, geosmin) may reduce ozone requirements (if not otherwise needed to achieve pathogen inactivation requirements). 2. Improved removal of organic compounds may reduce coagulant dosage requirements to meet water quality goals for total organic carbon (TOC ) and disinfection byproducts (DBP) precursor removal. 3. Reduced coagulant dosage may decrease solids handling requirements. 4. Improved removal of organic compounds may reduce disinfectant (chlorine) demand. 5. Decreased underdrain fouling may extend the life of existing underdrain infrastructure. Continued on page 8
Continued from page 6 6. Improved filter hydraulics will decrease backwash return volumes and the associated energy and chemical costs to dispose of or retreat the return water.
Conclusion Engineered Biofiltration strategies have shown operational benefits at pilot sites in Florida and Texas. Key conclusions include: Effectiveness of the strategies can be impacted by the type of coagulant used during pretreatment, coagulant carryover, and biofilter feed pH. The GAC may be a more robust support media compared to anthracite, but anthracite may offer cost advantages if performance objectives are met. Optimized biofiltration may yield cost savings and water quality benefits across multiple processes.
Acknowledgements This work was made possible through the financial contributions of the Water Research Foundation, Tampa Bay Water, Dallas Water Utilities, and the City of Arlington.
References • Lauderdale, C., Brown, J., Chadik, P, Kirisits, M. 2011. Engineered Biofiltration for Enhanced Hydraulic and Water Treatment Performance. Water Research Foundation, Denver. • Lauderdale, C., Scheitlin, K., Nyfennegger, J., Upadhyaya, G., Brown, J., Raskin, L., Chiao, T., Pinto, A. 2014. Optimizing Engineered Biofiltration. Water Research Foundation, Denver. • Mauclaire, L., Schurmann, A., Thullner, M., Gammeter S., and Zeyer, J., 2004. Sand filtration in a water treatment plant: biological parameters responsible for clogging. Journal of Water Supply: Research and Technology AQUA 53 (2) 93-108. • Nyfennegger, J., Lauderdale, C., Brown, J., Scheitlin, K. 2013. Engineered Biofiltration for Drinking Water Treatment: Optimizing Strategies to Enhance Performance. Florida Water Resources Journal, 11, 12-17. Jennifer Nyfennegger, Ph.D., P.E., is a senior technologist with Carollo Engineers Inc. in Sarasota; Jess Brown, Ph.D., P.E., is a vice president with Carollo Engineers Inc. in Orange County, Calif., and is the director of the Carollo Research Group; Kara Scheitlin, P.E., is technologist with Carollo Engineers Inc. in Denver; and Chance Lauderdale, Ph.D., P.E., is a vice president with HDR Engineering Inc. in Denver.
8
November 2014 • Florida Water Resources Journal
F W R J
Construction Manager At-Risk Implementation for a Water Treatment Plant Granular Activated Carbon Filtration Project Edward Alan Ambler, E. Devan Henderson, and Matt Peterson Edward Alan Ambler, P.E., LEED AP, is water resources manager with the City of Casselberry; E. Devan Henderson, P.E., is a project manager with Reiss Engineering Inc. in Winter Springs; and Matt Peterson is a project manager with Wharton-Smith Inc. in Sanford.
he City of Casselberry evaluated many alternatives to comply with the Stage 2 Disinfectants and Disinfection Byproducts (D/DBP) Rule compliance regulatory changes and selected implementation of granular activated carbon (GAC) filtration at its South Water Treatment Plant (WTP). The City performed preliminary planning on many different precursor removal and treatment methods, including ozonation, ultravio-
T
let radiation, GAC filtration, and changing disinfection methods to chloramination. Following preliminary selection of GAC, pilot testing was performed to evaluate precursor removal effectiveness. Reiss Engineering Inc. designed the GAC improvements and continued its services throughout construction as part of the implementation team. Wharton-Smith Inc. was selected as a construction manager at-risk (CMAR) contractor to perform the required GAC treatment process improvements at the WTP. The CMAR process provided a reduced construction schedule and allowed the City and engineer to maintain a nonadversarial relationship with the contractor, essentially allowing all parties to act as a construction team. The team worked together to reduce time on shop drawing submittals, request for information (RFI) reviews, and field changes, and actively pursued value engineering options throughout construction of the required improvements. The team also added to the scope of the initial project to greatly improve it, while reducing the construction schedule and keeping the project within budget.
Steps to Compliance
Figure 1. Casselberry Initial Distribution System Evaluation Sampling Plan
10
November 2014 • Florida Water Resources Journal
The City is in the process of upgrading its finished water treatment process at the WTP in order to comply with EPA’s Stage 2 D/DBP Rule. The EPA adopted the Stage 2 D/DBP Rule in 2006 and started working with potable water providers for completion of the Initial Distribution System Evaluation (IDSE) to evaluate the drinking water sampling plans implemented by those providers (Figure 1.) A major change between the Stage 1 D/DBP Rule and the Stage 2 D/DBP Rule is the implementation of the Locational Running Annual Average (LRAA) method of reporting samples. Previously, utility providers averaged the DBP concentrations from samples taken throughout the entire distribution system. The LRAA method tracks DBP results of specific sampling sites and requires reporting on every specific site. The City anticipated that it would be
Figure 2. Forced Draft Aerators
in noncompliance with the Stage 2 D/DBP Rule based on implementation of the LRAA method for the WTP. The City started preliminary planning for treatment alternatives and selected utilization of GAC filtration to remove the DBP precursors within the source water to ensure compliance with the Stage 2 D/DBP Rule. Unfortunately, the City was unable to construct the required capital improvement project prior to implementation of the Stage 2 D/DBP Rule and encountered its first Maximum Contaminant Level (MCL) exceedance in late fall of 2013.The City proceeded with the design of the required improvements, and design and permitting were completed in the winter of 2013. The City worked closely with the Florida Department of Environmental Protection (FDEP) to detail the process the City would follow to correct the MCL exceedances. The FDEP evaluated the information provided by the City and determined it was taking proactive measures to correct the MCL exceedance. The FDEP issued the City a compliance assistance offer instead of a consent order to make the necessary improvements. A compliance assistance offer is a letter presenting an action plan required to correct the regulatory violations. A consent order is a court-approved case dictating the terms of an agreement between a city and FDEP that could be enforced.
City and System Background Casselberry is a medium-sized community in urban Orlando that provides potable water to approximately 55,000 customers. The City owns and operates three water treatment
Figure 3. Trihalomethane Formation in Granular Activated Carbon-Treated Water
plants that treat and distribute potable water to its customers. The WTP currently supplies drinking water to meet an average annual demand (ADD) of 1.7 mil gal per day (mgd) and a maximum day demand (MDD) of 2.5 mgd. The existing WTP includes three groundwater wells, forced draft aeration, storage, and highservice pumps. The City currently disinfects the groundwater using sodium hypochlorite and adds orthopolyphosphate as a corrosion control inhibitor (Ambler et al, 2013). The groundwater from the wells at the WTP contains higher levels of hydrogen sulfide and organic content than the groundwater used as source water at the other two Casselberry WTPs. The forced draft aerators (Figure 2) at the WTP are used to reduce the levels of hydrogen sulfide in the finished water. Historically, the City observed higher levels of trihalomethane (THM) and haloacetic acids (HAA) levels in the southern portion of the City’s distribution system. Multiple sampling events from the GAC pilot study at the WTP indicate the average source water total organic carbon (TOC) is 1.7 mg/L, pH is 7.7, and the ultraviolet measure (UV-254) is 0.04 cm-1 (Ambler et al, 2013). It was anticipated that at these TOC levels, the City would be in violation of the Stage 2 D/DBP requirements, based on experience with other utilities in the vicinity. The City evaluated several options at the planning level to minimize the DBP formation, including the following: Inspection and remediation of the potable water wells Use of chloramines, ozone, or ultraviolet irradiation for disinfection instead of free chlorine
Unidirectional flushing to remove any debris or other material within the distribution system that would reduce the effectiveness of disinfection Autoflushers aimed at purging old water from the distribution system GAC filtration to remove the organics from the source water (Ambler et al, 2014) Many of the lower-cost options, such as operational changes, well remediation, and unidirectional flushing were completed, but little change in DBP formation was observed. The City anticipated this result and proceeded with conducting a pilot study for GAC at the WTP.
Granular Activated Carbon Pilot Study and Design During initial phases of the project, no facilities were operating at full scale with GAC treatment in the central Florida area to assess the efficiency of GAC to remove TOC from the groundwater; therefore, a pilot study was conducted at the WTP to define GAC design parameters. Over the course of three months, aerated well water was fed into two types (Calgon and Norit) of GAC-filled columns to monitor TOC and UV-254 (a surrogate of TOC) breakthroughs and determine the carbon regeneration rates. Treated water was tested for chlorination DBPs and various water quality parameters. The DBP formation potential was evaluated by dosing chlorine to the GAC effluent water, and to blends of GAC effluent with source water, to obtain representative DBP formation, rather than performing a theoretical extrapolation between source waContinued on page 12
Florida Water Resources Journal • November 2014
11
Continued from page 11 ters and blended streams. The chlorine dose applied was sufficient to provide chlorine residual from 0.4 to 1.8 mg/L after three days of contact time. Dose and contact time were selected to represent system operations and distribution system conditions. In general, results from the pilot study indicated that water treated with Calgon GAC media had lower THM and HAA (Figure 3). The THM concentrations for the Calgon media were about 55 µg/L after three days and about 60 µg/L for HAA. For the Norit GAC media, the THM concentration after three days was approximately 65 µg/L and about 70 µg/L for HAA. Based on the pilot study results, the following design criteria were developed for the design phase of the GAC system: Four 12-ft-diameter GAC vessels 40,000 lbs of carbon per GAC vessel Minimum empty bed contact time (EBCT) of 17 minutes at MDD
During the design phase of the project, multiple adjustments were made based on project team discussions to improve the operations at the WTP; these included GAC vessel incorporation into the process flow, bypass options, and an additional GAC vessel. The incorporation of the GAC vessels was selected following the aerators to prevent sulfide in the water from absorbing to the carbon and decreasing its TOC removal effectiveness. The existing clearwell was utilized and the pump station was upgraded to accommodate the change in head conditions required to pump the water from the clearwell through the GAC vessels into the ground storage tanks. This option was cheaper in cost compared to construction of a second pump station and allowed for less maintenance of equipment. The option was also simpler in terms of instrumentation and controls. Although the pilot testing indicated that treatment of full flow is necessary to achieve the desired reduction in DBPs, a bypass option
Figure 4. Maximum Contaminant Level Exceedance Notification
12
November 2014 • Florida Water Resources Journal
was included to aid operations with cost optimization in the event that the full-scale operations performed better than initial pilot testing. An additional GAC vessel was added to allow for increased flexibility and reliability. Five GAC vessels and the bypass allowed for the operations staff to run all WTP wells simultaneously, as well as decrease the number of deliveries required. Although not a requirement, decreased deliveries is an additional benefit for this facility since the WTP is located in a residential area.
Regulatory Summary and Severity of Risk Associated with Maximum Contaminant Level Exceedances In fall of 2013, while the design phase of the WTP improvements was ongoing, the City received its first quarterly sampling MCL exceedance associated with the implementation of the Stage 2 D/DBP Rule. Several sampling sites within the City’s distribution system exceeded the MCL limits for THMs. These sampling sites were previously averaged in with the remaining sampling sites, which had lower THM concentrations and reduced the overall THM average concentration for the entire distribution system. The sampling sites were now in violation because of implementing the LRAA change in the Stage 2 D/DBP Rule. The sampling sites were geographically focused within the influence zone of the WTP within the distribution system. The City reported the MCL exceedance to FDEP and both worked closely to determine the appropriate notification procedure. The City was required to send a one-page mailer (Figure 4) to all customers within its existing distribution system and place an advertisement in the local newspaper concerning the MCL exceedance. The notification contained one full page of complex language as specified by the U.S. Environmental Protection Agency (EPA) and FDEP and a contact number for the City for any questions. This notification was delivered to the City’s customer base in January 2014 and the City received well over 100 inquiries concerning the first notification. At the time, the City anticipated having to mail the notification every quarter until its GAC project was completed at the WTP, which was in December 2014. This timeline encouraged City staff to research additional information concerning MCL exceedances to include frequently-asked questions on its website and direct conversations with customers who had concerns over the public notification. Specific language within the public notification that appeared to bring the most concern
to the City’s customers is “Some people who drink water containing trihalomethanes in excess of the Maximum Contaminant Level over many years may experience problems with their liver, kidneys, or central nervous system and may have an increased risk of getting cancer.” This language is harsh and it is understandable how the City’s customer base could have reservations concerning drinking the City’s water. City staff researched the basis on which this determination was made to prepare City staff to answer the questions of its customers. During development of the Stage 2 D/DBP Rule, EPA determined the increased risk of developing cancer based on a reference dose (RfD) and health advisory (HA) limit. The RfD is a daily exposure level that is believed to be without appreciable health risk to humans over a lifetime. This RfD correlates to a 70-kilograms (kg) adult who consumes 2 litres of water per day over a 70-year lifetime. The HA limit for THMs and HAA is based on an upper-bound excess lifetime risk of 1 in 1 million. So, if customers consume a little more than a half-gal of City water over a 70-year period, they are 1 in 1 million times more likely to get cancer (EPA, 2007). In January 2004, the American Water Works Association (AWWA) issued a 126-page letter (Figure 5) to EPA officially responding to the proposed rule making for Stage 2 D/DBPs. The Association commended EPA for all of its work developing the Stage 2 D/DBP Rule (done in conjunction with AWWA), but offered three main defects to the proposal: The definition of significant excursions and the resulting actions required of utilities are inappropriate. The AWWA defines significant excursions as individual high THM or HAA compliance sample values that place a water provider close to or into noncompliance with either the Stage 2 D/DBP THM or HAA5 MCLs. The bias in the presentation of health-effects data is so pervasive that it calls into question EPA’s obligation and commitment in the agreement in principle to issue a regulation that complies with applicable law and regulation. The quantification of health effects that may or may not be realized through the new MCLs is inappropriate, particularly in areas where the agency specifically concluded that quantification was not possible in “illustrative examples” (AWWA, 2004). The low risk (1 in 1 million) of developing cancer (EPA, 2007) from the City’s potable water that exceeded the MCLs for THM and HAA, coupled with AWWA’s comments on the Stage 2 D/DBP Rule development, did not ap-
Figure 5. AWWA Letter to EPA on Stage 2 D/DBP Rule Promulgation
pear to make answering customers complaints or comments any easier for City staff. However, the City was still in violation of the MCL limits as imposed by the Stage 2 D/DBP Rule and began extensive communication with FDEP on how to correct the MCL exceedance.
Compliance Assistance Offer With Florida Department of Environmental Protection The FDEP had several options available to ensure that the City would take corrective action to address the MCL exceedance and bring its potable water into compliance with regulations. Compliance assistance is one of the four tools available that EPA and FDEP use for promoting or addressing compliance with regulations. Compliance assistance primarily includes activities, tools, or technical assistance to help the regulated community meet its regulatory obligations. Another method, compliance monitoring, involves on-site visits by qualified inspectors and review of required agency submittals. Compliance incentives are a set of policies and programs that eliminate, reduce, or waive penalties for businesses, industry, and government agencies that voluntarily discover, promptly correct, and/or prevent future environmental violations. Another tool is enforcement actions, which are defined as civil enforcements that protect human health and the environment by taking legal action to bring polluters into compliance with the law. An administrative order can be issued with or without penalties that directs an individual, business, or other entity to take action to come into compliance or to clean up a site (http://www.epa.gov). City staff requested a meeting with staff from FDEP to discuss the MCL exceedance violation and the City’s plans to correct the deficiency. City staff subsequently explained in extensive detail the preliminary planning ef-
forts, pilot study, design for GAC improvements, and preliminary efforts the City had made to construct the improvements via the CMAR method. The City had received a construction permit for the project approximately a week prior to meeting with FDEP about the MCL exceedance. The FDEP acknowledged that the City had been making significant effort to correct the MCL exceedance; however, the City was unable to construct the required improvements prior to the implementation of the new regulations The FDEP elected to offer a compliance assistance offer instead of an alternative enforcement action, such as a consent order. The compliance assistance offer still maintained the minimum regulatory actions required, such as continued quarterly sampling and public notification in the event of MCL exceedance. Additional information, such as continued monthly updates on the status of construction of the GAC project at the WTP and voluntary inspections, were required within the compliance assistance offer. Complying with these requirements and maintaining the established project schedule without further MCL exceedance once the GAC treatment upgrades are placed into service will allow the issue to be resolved without enforcement. The FDEP understood that the City was progressing towards resolving the problem and it wanted to work with the City without involving burdensome enforcement procedures.
Construction Management At-Risk Method Benefits As design documents were finalized, Wharton-Smith was contacted for preconstruction services for construction of the GAC treatment system at the WTP. With the City being up against the compliance deadline set forth by the compliance assistance Continued on page 14
Florida Water Resources Journal • November 2014
13
Continued from page 13 offer, the CMAR delivery method was the best-suited contract delivery method for this project. Benefits in using the CMAR delivery method for the GAC treatment addition at the WTP include: Selection of contractor and subcontractors based on qualifications Preconstruction services Expedited schedule Construction manager minimizing change orders by establishment of an owner contingency within the guaranteed maximum price (GMP) Transparency of cost control
Selection of a Construction Manager At-Risk Contractor The CMAR delivery method is the best contract delivery method to fast-track a project while maintaining a high quality level. This project built upon the previous success that all of the represented firms had established. Key staff members on each team were identified that performed together well on previous projects and that were assembled for this project. Several meetings were held early in the process to establish goals, objectives, and a clear path for project success.
Preconstruction Services and Value Engineering Preconstruction involvement of the construction manager (CM) adds value by injecting the builder’s insight into the project prior to the establishment of the GMP. It is in the owner’s interest to select a construction manager early in the design phase so that CM preconstruction services provide the best value to the project (Kaplin and Conley, 2009). In the beginning phases of the GMP establishment for the project, it was apparent that this project would be over budget for previous funds allotted by the City. A thorough review of the contract documents was done, which generated questions to avoid scope gaps, add valueminded changes, and address potential conflicts in the contract drawings. As the CMAR, Wharton-Smith was responsible for creating bid packages for subcontractors and vendors and providing bidding services to the City for the project. The questions and answers generated in preconstruction review may have minimized the value engineering (VE) offered after establishment of the GMP, but they allowed for competitive bid pricing on value-minded changes and scope gaps during the question-and-answer process, which reduced the overall cost of the project. Con-
14
siderable effort was made during design of the project to minimize construction costs, so it was not surprising that there was not much opportunity for additional VE on the project. At the early stages, it was essential to award the project and start construction as soon as possible to meet the pressing schedule requirements.
Cost Control, Transparency, and Owner Contingency In a CMAR delivery method, the CM is compensated for actual costs incurred, general conditions, and the CMAR fee. General conditions are defined as support costs during construction, such as field trailers, utility usage, materials testing, survey, security, dumpsters, and similar auxiliary costs required to complete the project (Kaplin and Conley, 2009). Invoices and backup documents for all costs are submitted with the monthly pay requisition as a transparent “open book” accounting relationship with the owner; this provides assurance that all involved parties are being good stewards of the rate payers’ money. Being good stewards was defined as a primary objective early on in initial project meetings and has been clearly adhered to throughout design and construction of the project. Included in the GMP, the City provided for a contingency which can only be used upon mutual agreement among the involved parties. The purpose of this contingency is to protect the City from unforeseen conditions, scope gaps, and/or design errors and omissions that would typically result in contract change orders. One of the many successes of the project is that the contingency has remained protected throughout construction. After construction progressed far enough along, with the contingency remaining unspent, a portion of it was refunded to the City to fund alternative projects outside of the scope of the WTP project.
Conclusion The City of Casselberry performed extensive preliminary planning work and pilottested the effectiveness of GAC in conjunction with existing forced draft aeratoration at the WTP, the only treatment plant in Casselberry’s system that supplied potable water that did not meet the Stage 2 D/DBP Rule. The GAC proved to be an effective treatment method for the removal of organic matter, which contributed to THM and HAA formation levels that exceeded the MCLs under the revised regulations. Significant capital improvement and operating costs are associated with design and
November 2014 • Florida Water Resources Journal
construction of GAC improvements to treat the source water at the WTP. The City worked closely with FDEP to illustrate all of the efforts the City completed in an attempt to meet the Stage 2 D/DBP regulations. The FDEP offered an alternative to enforcement action with a compliance assistance offer since the City had a defined correction plan. The City was required to provide continued notifications to its entire customer base for every failed LRAA each quarter, which is costly and requires significant interaction with the customers. City staff performed extensive research on the adverse health effects of MCL exceedance and was partially able to convey this message to its customer base. It would be helpful if EPA could provide additional guidance to clarify these adverse health effects, as requested by AWWA. The CMAR project delivery method was selected as the best method to meet the aggressive schedule and ensure quality delivery of construction of the improvements. Establishing a clear goal of being good stewards for the rate payers at the beginning of the project was successful in encouraging the team to make continual strides to meet the goal. The City has maintained a successful project schedule and is anticipating completing the WTP project in December 2014. Compliance with the Stage 2 D/DBP regulations could potentially have a furtherreaching effect on utility providers than EPA may have initially predicted, specifically due to the changes with implementing LRAAs.
References • Edward Alan Ambler, Greg Goodale, Dawn Swailes, Steve Black, Edward Talton, Glenn Dunkelberger, Ferdinand Vasquez, 2013. “Granular Activated Carbon for Stage 2 D/DBP Rule Compliance, City of Casselberry.” • Edward Alan Ambler, E. Devan Henderson, Glenn Dunkelberger, 2014. “Stage 2 D/DBP Rule: Granular Activated Carbon Following Forced Draft Aeration.” • Kaplin, John, and James Conley. "Construction Management at-Risk as a Delivery Method for Water Projects." New England Water Works Association, 2009 Annual Conference (2009): 4. • American Water Works Association, Jan. 16, 2004. “Stage 2 Disinfectants and Disinfection Byproducts Rule: National Primary and Secondary Drinking Water Regulations: Approval of Analytical Methods for Chemical Contaminants, Proposed Rule, 68 Federal Register 49547, OW-2002-0043.” • EPA, 2007. “Drinking Water Standards and Health Advisories Table.” USEPA, Region 9.
Florida Water Resources Journal • November 2014
15
16
November 2014 • Florida Water Resources Journal
Florida Water Resources Journal • November 2014
17
18
November 2014 • Florida Water Resources Journal
Florida Water Resources Journal • November 2014
19
Certification Boulevard
Test Your Knowledge of Water Treatment Topics Roy Pelletier Scott Ruland, water and wastewater manager, City of Deltona, provided these questions and answers. Thank you, Scott, for providing such great water operator information. 1. What is the major factor affecting the efficiency of the aeration process in a water plant? a. Concentration of volatile organic compounds (VOCs) b. Iron levels c. Surface contact between air and water d. Flow rates 2. Algal blooms may create several problems such as tastes and odors, depletion of oxygen in the source water, and additional organic loadings. What is another problem associated with algal blooms? a. Increased pH b. Decreased diatoms c. Reduced trihalomethane (THM) formations d. Aerobic conditions 3. One primary purpose of the inlet zone of a sedimentation basin is to distribute the water evenly into the sedimentation basin. What is the other purpose of the inlet zone? a. Provide additional mixing through baffles b. Control water velocity as it enters the basin c. Provide an area for visual inspection d. Provide a sampling location to confirm coagulant dosages 4. What test can be performed that will give an operator a quick indication of the performance of the sedimentation process? a. b. c. d.
20
Turbidity into and out of the tank Conductivity into and out of the tank Coliform sampling at the tank outlet Dissolved oxygen content to verify there is no anaerobic conditions “septic sludge”
5. Which process is used to rapidly mix and disperse a coagulant chemical with raw water? a. b. c. d.
Hydraulic mixing Mechanical mixing Diffuser mixing Flash mix
6. What is the optimum pH range for coagulation? a. 5 to 7 c. 7 to 8
b. 6 to 7 d. Greater than 8
7. What type of corrosion occurs when two dissimilar metals are joined together? a. b. c. d.
Stray current corrosion Galvanic corrosion Immersion corrosion Dielectric corrosion
LOOKING FOR ANSWERS?
Check the Archives Are you new to the water and wastewater field? Want to boost your knowledge about topics youʼll face each day as a water/wastewater professional? All past editions of Certification Boulevard through the year 2000 are available on the Florida Water Environment Associationʼs website at www.fwea.org. Click the “Site Map” button on the home page, then scroll down to the Certification Boulevard Archives, located below the Operations Research Committee.
8. What is not one advantage of using chloramines as a disinfectant? a. Reduces the formation of THMs b. Penetrates the biofilm on pipe walls to kill microorganisms c. Reduces tastes and odors d. They are a stronger disinfectant than chlorine 9. What undesirable condition can occur from opening and closing a valve to quickly? a. b. c. d.
Water hammer Tuberculation Backsiphonage Backflow
10. What type of filter media is used to remove tastes and odors? a. b. c. d.
Granular activated carbon Clay brick Garnet Alum
November 2014 • Florida Water Resources Journal
Answers on page 56
SEND US YOUR QUESTIONS Readers are welcome to submit questions or exercises on water or wastewater treatment plant operations for publication in Certification Boulevard. Send your question (with the answer) or your exercise (with the solution) by email to roy.pelletier@cityoforlando.net, or by mail to: Roy Pelletier Wastewater Project Consultant City of Orlando Public Works Department Environmental Services Wastewater Division 5100 L.B. McLeod Road Orlando, FL 32811 407-716-2971
FSAWWA SPEAKING OUT
Mentoring Program Increases Section Participation and Sparks Creativity Carl R. Larrabee Jr. Chair, FSAWWA
ow many of you reading this are members of AWWA and not actively participating in the organization? I’d suspect quite a few. Don’t worry; I’m not going to put a guilt trip on you. Quite the contrary— I’m going to offer a solution. Has anyone asked you to become more active? Has an opportunity for you to do something really good with other Florida Section members come to your attention that you just would not want to miss, but you missed it anyway? I suspect unless you have commitments that are more pressing in your life, the answer would be “No.” Membership in the association is the best way to learn more about all facets of the water industry, network with your peers, and establish lifelong friendships with some great people. It’s not happening for everyone in the association, and you may be one of them. The new AWWA mentoring program has the potential for changing that for many new members. The program matches new members with existing members, and to date, there are 20 pairings in the section. That means that 20 new members have someone special in our association to talk with, introduce them to other members, and assist them in matching their interests to section efforts on committees and/or councils. For those of you who would like to participate, the link to the application form is on the www.fsawwa.org home page. Casey Cumiskey, the FSAWWA training coordinator/membership specialist, is our staff mentoring program contact and expert extraordinaire! She can be reached at fsawwa.casey@gmail.com or (407) 957-8447. The section has over 100 committees with many different topics including research, backflow protection, legislative, regu-
H
latory policy, Water For People, water tower competition, membership, mentoring, customer service, treatment plant and operators awards (where I started!), fall conference, Likins scholarship, information technology, and finance, to name a few. Each section committee has a chair, and preferably, but not always, a vice-chair. The position of vice-chair is an excellent opportunity to hone leadership skills while working under the tutelage of the chair. You might be thinking, “I’m new at work, I just got married, I’m active in my church, and/or my first child just arrived—how much time is any of this AWWA stuff going to take anyway?” These are all important considerations when deciding whether or not to become more active. My section activities were done primarily at work. My supervisor, Bill Stephenson, was an active AWWA member. He was the previous Treatment Plant and Operators Awards Committee chair and later became the section chair. Not all supervisors are that active in AWWA, but if they have experience in the water industry, they should know the critical role AWWA plays in making drinking water in America the most excellent in the world. Ask your supervisor if you could set aside some time for FSAWWA activities. When I attended an AWWA annual conference (ACE), my wife, Janis, and daughters accompanied me. My oldest daughter, Jessica, had her first flight to the Dallas ACE when she was 8 months old. She and her sister, Joye, have wonderful memories of exploring the exhibition halls over the years. Sightseeing in our nation’s capital was one of many activities my family experienced, which we’ve also done in the other major cities that have hosted this convention. Your active participation in the section can increase your knowledge of the industry and grow connections to experienced peers that will benefit your employer in countless ways. Personally, you will cherish the lifelong friendships developed through the association. I know—I have them! You may have heard this phrase and be
recognizing it in your career: The more you know, the more you know you don’t know. A twist on that phrase is that the more you know, the more you know you could know. In other words, the more you realize what’s being done, the more you realize what could be done. That’s the phrase I’d like to see us cultivate. The section is involved with many waterrelated projects and issues. A less active member might just need to find out the one that interests him or her and get connected. But what if there’s something that interests someone that isn’t being addressed right now? Is there a method in place to find it and make it happen? Not yet, exactly, but I’d like to introduce you to a new initiative. I’d like to see us solicit ideas of all kinds to improve any and all aspects of the water industry. Whether or not the originator is willing and/or able to work on the idea doesn’t matter. Either way, it should be placed in a depository for future consideration and possible action. I’d love to see a treasure trove of ideas that anyone in our section can contribute to and look through to find something that fits their skills and interests that they can then adopt and work on. In order to make this happen we might need another committee—a New Water Idea Discovery, Development, Assignment, and Implementation Committee! You may be a dreamer and can imagine new ideas that would be excellent for us to explore. You may be a doer who just needs an idea to spark your creativity. You may take the lead or you might work under a great leader who can show you how it’s done. Take the initiative today—right now— to start taking full advantage of your membership in AWWA. Connect. Contribute. Enjoy the lifelong journey. I also hope to see you at the section’s fall conference, being held November 30 through December 4, where lots of new ideas will be generated and discussed. The Young Professionals Committee is having a joint luncheon with the mentoring program mentors and mentees on Tuesday at the event. Don’t miss it!
Florida Water Resources Journal • November 2014
21
T E C H N O L O G Y
S P O T L I G H T
Biofiltration: No Longer a Dirty Word for Drinking Water Treatment Roger K. Noack Generally, when one hears the word “biofiltration” the first thing that comes to mind is a trickling filter in a wastewater treatment plant—smelly, yucky, and big! However, biofiltration is becoming an accepted drinking water treatment process for the removal of many contaminants found in today’s source water supplies. Biofiltration can be as simple as a conventional media filter operated without chlorine residual, or it can be combined with an advanced oxidation process (AOP), such as ozone. Drinking water biofiltration has become commonplace, with over 15 bil gal per day of installed capacity in water treatment facilities across the United States. These facilities can achieve filter loading rates from 2 to 10 gpm/ft2 and higher, using design and operational parameters similar to conventional filters. Indeed, biofiltration is no longer a dirty word for drinking water treatment. To understand how biofiltration can be effective in treating source water, it is important to understand biofiltration basics. Similar to a trickling filter, a media substrate or support structure, such as sand, anthracite, or granular activated carbon, is required. The media provide a place for naturally occurring bacteria to attach and grow in a matrix known as “biofilm.” Biofilm is composed of microbial cells, their metabolic byproducts, and filtered particles. In a biofilter, water treatment is achieved through microbial activity, biofilm and media surface chemistries, and basic filtration. Filter influent flows over the biofilm, where absorption and diffusion allow bacteria to capture and metabolize natural organic matter, metals, or trace organic contaminants (e.g., pharmaceuticals, pesticides, tastes and odors, etc.). Simply put, biofiltration employs bacteria to “eat” the undesirable contaminants, changing them to innocuous byproducts or removing them entirely.
Biologically Active Filtration What stimulates microbial growth in a biofilter? The list includes organic and inorganic substrates naturally found in source water, as well as those created by treatment processes, such as chlorination or ozonation. Raw water contaminants are somewhat source dependent. For instance, nitrates and perchlorates are generally found only in groundwater sources. Taste- and odor-causing compounds, geosmin, and 2-methylisoborneol (MIB) produced
by blue-green algae, are found only in surface waters or groundwater under the influence of surface water. Each source, and how biofiltration will treat the problematic constituent, will be explored. Source aquifer characteristics dictate what one can reasonably expect to find in the groundwater supply. For instance, rainwater passing through aquifer recharge areas containing natural organic matter lenses can exhibit high ammonia concentrations. Here are just a few of the typical primary constituents that can be removed with biofiltration: • Iron • Ammonia • Manganese • Nitrate • Hexavalent chromium • Perchlorate • Volatile organic carbon Surface water sources are generally more complex than groundwater because of various terrestrial influences that can affect water quality. When a densely forested wetland experiences a drought, existing ponds and retained water evaporate, concentrating nutrients and organic matter across the watershed. When the rains come, the nutrient- and organic-laden water is carried to a potential surface water supply, leading to increased color and total organic carbon levels, and possibly blue-green algal blooms. In addition, certain surface water treatment processes will alter the available dissolved constituents, creating undesirable compounds. For instance, using free chlorine for disinfection will change some dissolved organics into regulated disinfection byproducts (DBPs) with public health implications. This means that the location of the biofilters is somewhat dependent on what the raw water constituents are and the treatment processes utilized. Installing biofilters at the head of a surface water treatment plant is a relatively new twist. However, when one considers some of the contaminants that need to be removed earlier rather than later, it makes a lot of sense. Surface sources are prone to algal blooms when the water is hot and nutrients are high. With the algae blooms, two troublesome contaminants that do not affect regulatory quality but have a huge aesthetic impact are geosmin and MIB. The generally accepted method for removing these constituents is adsorbing them into powdered activated carbon (PAC). Using PAC is costly and not always effective because not enough PAC is added or there is not enough contact time for the compounds to be adsorbed onto the carbon particles. With biofil-
tration, extremely high concentrations of geosmin and MIB (in the ppm range versus the 3 to 5 ng/l threshold level) can easily be removed. In addition to geosmin and MIB, biodegradable organic matter that can lead to high DBP levels should be removed earlier rather than later, and certainly prior to application of a disinfectant. If the source is subject to conditions that contribute to high levels of these types of contaminants, or others, such as endocrine disruptors and pharmaceutically active compounds, then placing biofiltration at the head of the plant should be considered, if possible. Typically, biofiltration is the final treatment process. It “polishes” finished water by removing constituents and assimilable organic carbon (AOC) created by ozonation, which may cause regulatory problems or affect distribution water quality. It also functions as a granular media filter to provide final turbidity removal, as well as a physical barrier to pathogens. Ozone is a powerful oxidant used to destroy taste and odor compounds or disinfectant-resistant protozoans, such as Cryptosporidium oocysts. Because ozone is so powerful, when it is injected into the water, it oxidizes complex natural organic macromolecules and converts the organic matter into smaller, more readily degradable organic compounds known as AOC. If not removed through biofiltration, AOC can lead to distribution water quality problems, including bacterial regrowth, corrosion, and reduced disinfectant residual. Fortunately, AOC can be removed with biofiltration, because the microorganisms populating the filter love eating the bite-size organics that remain after ozonation. Another benefit of biofiltration is reducing treated water total organic carbon (TOC) levels. The TOC reacts with disinfectants to form regulated DBPs, such as trihalomethanes and haloacetic acids, as well as unregulated DBPs. Reducing TOC before free chlorine disinfection reduces DBPs, providing numerous public health benefits. Biofiltration can also be effective at biodegrading haloacetic acids that form prior to biofiltration. Using the correct treatment methods, biofiltration does not have to be the smelly and yucky process many have traditionally associated with it. Instead, it can provide cost-effective treatment of metals, organics, taste and odor compounds, and contaminants of emerging concern. Roger K. Noack, P.E., is east region desalination leader at HDR Engineering Inc. in Tampa.
Technology Spotlight is a paid feature sponsored by the advertisement on the facing page. The Journal and its publisher do not endorse any product that appears in this column. If you would like to have your technology featured, contact Mike Delaney at 352-241-6006 or at mike@fwrj.com.
22
November 2014 • Florida Water Resources Journal
F W R J
Disinfection Byproduct Formation Potential Reduction and Hydrogen Sulfide Treatment Using Ozone Greg Taylor, Charles DiGerlando, and Christopher R. Schulz he Orlando Utilities Commission (OUC) is performing an upgrade and replacement program for the ozone treatment systems at all seven OUC water treatment plants (WTPs). The plants utilize liquid oxygen (LOX) as the feed gas for the ozone generation equipment. In order to standardize equipment and increase ozone generation and dissolution efficiencies, OUC and CDM Smith are performing a design and implementation plan for the treatment system upgrades at each of the WTPs. The purpose of this testing is to outline the procedure and interpret the results from the fullscale ozone system testing at three of OUC's plants and the effects on the sizing of the ozone generation and dissolution systems. The goals from this testing effort are to: Determine the base ozone demand for hydrogen sulfide (H2S) oxidation. Measure and trend the ozone decay rate in the raw water at various ozone-applied doses. Ascertain possible effects and correlations of the ozone-applied dose to the disinfection byproduct (DBP) formation potential of the raw water. Establish ozone-to-sulfide dose ratio that will be applied to each facility for the design of the system improvements.
T
The three facilities used for the testing are the Conway, Navy, and Pine Hills WTPs. These facilities were chosen because they represent a wide range of flows and water quality constituent concentrations with regards to all seven WTPs and will be used to represent the other facilities. The Pine Hills WTP has the lowest H2S and lowest average total organic carbon (TOC) concentrations, the Conway WTP has midrange concentrations of H2S and TOC in the raw well water, and the Navy WTP has a higher concentration of H2S in its two wells.
Process Testing Protocol The three facilities have the same basic flow scheme and attributes: raw water wells, ozone generation with liquid oxygen as the feed gas and fine-bubble diffusion dissolution system, ozone residual sampling and monitoring, chlorination,
24
and storage and pumping. The overall protocol for testing involves: Locating the sample lines for ozone residual monitoring. Operating at a constant well flow through one ozone contactor, with the same wells operating continuously throughout the testing. Setting the ozone-applied dose to a constant level for selected wells for steady state flow. Sampling the selected wells for water quality data, such as H2S concentration, pH, temperature, oxidation reduction potential (ORP), and dissolved oxygen (DO). Transferring the ozone residual monitoring device from the nonoperating contactor to the second sample point location on the operating contactor. Calibrating the ozone residual devices. Performing ozone demand and decay tests. Gathering samples for DBP formation potential tests and for other water quality parameters. The testing started with the base-applied ozone dose, or “base dose,” resulting in an approximate ozone residual of 0.1 mg/L, which represents the dose required to achieve complete oxidation of hydrogen sulfide in the raw well water. Subsequent ozone-applied doses of 0.5, 1.0, 1.5, and 2.0 mg/L above the base dose were also used for testing. For each applied ozone dose, ozone decay tests were performed, along with trihalomethane formation potential (THMFP) tests.
Conway Water Treatment Plant Setup and Methodology The reporting sample point for ozone residual at this facility is sample point No. 2 (SP 2). The on-line ozone analyzer is mounted to the side of the contactor and gathers its samples from a sample line feeding into cell No. 2 of Contactor No. 1. There is a sample pump that helps draw the water out of the contactor and through the analyzer header, which assists with lowering the sample line residual time. For this testing procedure, a bypass line was opened to increase the flow through the sample lines drawn for sample
November 2014 • Florida Water Resources Journal
Greg Taylor, P.E., is senior project manager with CDM Smith in Orlando; Charles DiGerlando, P.E., is senior engineer with Orlando Utilities Commission; and Christopher R. Schulz, P.E., is senior vice president with CDM Smith in Denver.
point 1 and sample point 2, reducing the residence time in the sample piping. The flow through the sample lines was measured using a graduated beaker and a stopwatch. Each flow test was performed three times for the bypass line and analyzer flows. The flow through the bypass line, which was measured to be approximately 4.23 gal per minute (gpm), is the total for SP 1 and SP 2. The flow through the analyzers was measured to be approximately 0.39 gpm. This corresponds to a flow of 2.5 gpm from SP 2, with a lag time of 15 seconds. Calibration The calibration of the ozone analyzers was performed by placing the two ozone analyzer units in series. For 10 minutes, the readings from the analyzers were recorded at 15-second intervals. Concurrently, every 2 minutes a grab sample was taken and analyzed for ozone concentration using a spectrophotometer, and all results were recorded. After the calibration cycle was completed, the recorded measurements from both analyzers and the grab samples were plotted against time. If the grab samples are close to the analyzer readings and are within ±1 standard deviation from the average analyzer reading, the analyzers are considered calibrated. The analyzers at Conway were not adjusted after the calibration testing. Results Raw Water Well Testing During the ozone process testing, OUC staff performed raw water well tests on the wells that were in operation during the testing. The tests for the raw water wells included: H2S concentration, temperature, pH, ORP, and DO. Table 1 shows the results from the raw water well testing.
The H2S concentrations are used to help define the “base ozone dose” for hydrogen sulfide oxidation and confirm the applied ozone doses utilized during testing. Ozone Demand Characteristics The average H2S concentration from the three Conway WTP operating wells was 2.53 mg/L. For test scenario B1, the raw water was treated with an applied ozone dose of 10 mg/L (~0.1 mg/L ozone residual at SP 2), which represents an ozone-to-sulfide ratio of approximately 4:1. Table 2 shows the scenarios performed, the corresponding ozone dose, well flow, and ozone production for each scenario. The testing was performed in the order of B4, B3, B1, B2, and B6. Scenario B2 and B5 were performed under the same conditions. With multiple people running various tests, the nomenclature for the operating scenarios were slightly miscommunicated the first day. The applied ozone doses were the overriding factor for the testing scenarios and were used to correlate the different naming conventions. The DBP testing for scenario B2, with an applied ozone dose of 11.5 mg/L, was repeated the second day, and given the name of B5. The testing for Conway occurred over two calendar days and allowed fine-tuning of the testing procedures, coordination, and result reporting. Ozone Decay Characteristics Before the decay tests were performed, the plant was operated at a steady applied ozone dose (depending on trial run) and a flow of 16.5 mil gal per day (mgd) for a minimum of 30 minutes to obtain a steady ozone residual and dose for the raw water. For each scenario, the decay test was performed twice. Figure 1 shows the decay test results for the first test performed for each scenario The data show a logarithmic decay of the ozone residual in the water. The natural log of the ratio of measured ozone concentration to initial ozone concentration data were then plotted against time in order to get the decay coefficients at the various ozone-applied doses. The slope of the trend line of each of these scenarios is the decay coefficient for the ozone decay at each applied dose. Table 3 presents the average decay coefficients. The decay data show the ozone decay rate that will be utilized when designing the ozone system to prevent any possible ozone residual carry-over from the contactors to the ground storage tanks.
Table 1. Conway Water Treatment Plant – Raw Water Well Test Results
Table 2. Conway Water Treatment Plant Ozone Testing Scenarios
Figure 1. Conway Water Treatment Plant Ozone Decay Results (First Test)
Table 3. Conway Water Treatment Plant Average Ozone Decay Coefficients
Trihalomethane Formation Potential After each decay test was performed, and before changing the applied ozone dose for the next scenario, samples of the treated water were taken Continued on page 26 Florida Water Resources Journal • November 2014
25
Continued from page 25 from the last sample point at the back of the contactor. This sample was then taken to the OUC water laboratory and a simulated distribution system (SDS) test was performed to determine the THMFP of the treated water. As stated previously, Scenario B5 is a repeat sample of scenario B2 (11.5 mg/L applied dose). Figure 2 shows the SDS results and Figure 3 shows a 48-hour THM concentration for each scenario. The 48-hour time period was selected based upon the target design water age for the water distribution system. These data indicate that there is not a significant impact of ozone dose on the THMFP of the treated water. The variability of ozone application and residuals could have impacted the consistency of DBP testing. If sidestream injection and/or a more consistent ozone dose and ozone residual can be achieved, DBP testing should be performed again.
Navy Water Treatment Plant Figure 2. Conway Water Treatment Plant Trihalomethane Formation Potential for Each Scenario
Figure 3, Conway Water Treatment Plant 48-Hour Trihalomethane Concentrations for Each Scenario
Table 4. Navy Water Treatment Plant – Raw Water Well Test Results
Setup and Methodology The reporting sample point for ozone residual at this facility is sample point No. 1 (SP 1). The on-line ozone analyzer is mounted to the side of the contactor and gathers its samples from a sample line feeding into cell No. 2 of Contactor No. 1. After the ozone analyzers, the sample lines come to a common header where a sample pump helps draw the water out of the contactor, lowering the sample line residual time, and pumps it back to the top of the contactor for retreatment. A rotameter is used to measure flow through the sample line pumping system. For this testing procedure, the pumped flow was measured using the rotameter, which was calibrated by the OUC water production operators. Flow through the on-line analyzers was measured using a graduated beaker and a stopwatch. Each test was performed three times for the analyzer flows. The flow through the sample pump was measured to be approximately 8 gpm (4 gpm from each sample point), and the flow through the analyzers was measured to be approximately 0.2 gpm. This represents a lag time for SP 1 of approximately 3 seconds. Calibration The calibration of the ozone analyzers was performed in the same manner as for the Conway WTP. After the calibration cycle, the SP 1 online analyzer was adjusted down 0.3 and the SP 2 analyzer was adjusted down 0.1. Results Raw Water Well Testing During the ozone process testing, OUC Continued on page 28
26
November 2014 • Florida Water Resources Journal
Table 5. Navy Water Treatment Plant Ozone Testing Scenarios
Continued from page 26 staff performed raw water well tests on Well number 1, the well that was in operation during the testing. The tests for the raw water well included: H2S concentration, temperature, pH, ORP, and DO. Table 4 shows the results from the raw water well testing. Ozone Demand Characteristics The average H2S concentration from the one operating Navy WTP well was 2.02 mg/L. For test scenario B1, the raw water was treated with an applied ozone dose of 8 mg/L (~0.1 mg/L ozone residual at SP 1). This represents an ozone-to-sulfide ratio of approximately 4:1. Table 5 shows the scenarios performed, the corresponding ozone dose, well flow, and ozone production for each scenario. The testing was performed in the order of B3, B5, B1, B4, and B2.
Figure 4 . Navy Water Treatment Plant Ozone Decay Tests (First Test)
Table 6 . Navy Water Treatment Plant Average Ozone Decay Coefficients
Table 7. Pine Hills Water Treatment Plant – Raw Water Well Test Results
28
November 2014 • Florida Water Resources Journal
Ozone Decay Characteristics Before the decay tests were performed, the plant was operated at a steady applied ozone dose (depending on trial run) and flow (5.7 mgd) for a minimum of 30 minutes to obtain a steady ozone residual and dose for the raw water. For each scenario, the decay test was performed twice. Figure 4 shows the decay test results for the first test performed for each scenario. The data show a logarithmic decay of the ozone residual in the water for all but the B1 scenario. The natural log of the ratio of measured ozone concentration to initial ozone concentration data were then plotted against time in order to get the decay coefficients at the various ozoneapplied doses. The slope of the trend line of each of these scenarios is the decay coefficient for the ozone decay at each applied dose. Table 6 presents the average decay coefficients. The decay data show the ozone decay rate that will be utilized when designing the ozone system to prevent any possible ozone residual carry-over from the contactors to the ground storage tanks. Trihalomethane Formation Potential After each decay test was performed, and before changing the applied ozone dose for the next scenario, samples of the treated water were taken from the last sample point at the back of the contactor. This sample was then taken to the OUC water laboratory and an SDS test was performed to determine the THMFP of the treated water. Figure 5 shows the SDS results and Figure 6 shows a 55-hour THM concentration for each scenario. The 55-hour samples have the closest water age to the OUC distribution system target water age, which is 48 hours. The applied chlorine dose for the B3 test was 0.5 mg/L less than the other samples. This lower chlorine dose caused the free chlorine residual to drop
below 0.2 mg/L after the 41-hour sample was analyzed. The THMFP testing is to be stopped after the chlorine residual drops below 0.2 mg/L. As a policy, OUC designs the distribution system for a maximum water age of 48 hours. At the 55-hour testing period, there does not appear to be an advantage to an increased ozone dose to reduce the THMFP of the treated water. There does seem to be a 10-12 mg/L drop in THMFP with the additional 1 mg/L of ozone added to the water; however, these tests should be repeated following construction of the ozone improvements at this WTP, and more data collected for a lesser number of time intervals to better establish this relationship.
Pine Hills Water Treatment Plant Setup and Methodology The reporting sample point for ozone residual at this facility is sample point No. 2 (SP 2). The on-line ozone analyzer is mounted to the side of the contactor and gathers its samples from a sample line feeding into cell No. 2 of Contactor No. 1. After the ozone analyzers, the sample lines come to a common header where a sample pump helps draw the water out of the contactor, lowering the sample line residual time, and pumps it back to the top of the contactor for retreatment. There is not a rotameter on this header, so the flows were measured using a stopwatch and a graduated beaker. Each test was performed three times for the analyzer flows. The flow through the sample pump was measured to be approximately 5.3 gpm (2.65 gpm from each sample point), and the flow through the analyzers was measured to be approximately 1.07 gpm. This represents a sample lag time for SP 2 of 1.2 seconds. Calibration The calibration of the ozone analyzers was performed following the same procedure as the Conway WTP. After the calibration cycle, the SP 2 online analyzer was adjusted up 0.1 to match the SP 1 analyzer and the grab samples. Results Raw Water Well Testing During the ozone process testing, OUC staff performed raw water well tests on the wells that were in operation during the testing. The tests for the raw water well included: H2S concentration, temperature, pH, ORP, and DO. Table 7 shows the results from the raw water well testing.
Figure 5 . Navy Water Treatment Plant Trihalomethane Formation Potential for Each Scenario
Figure 6. Navy Water Treatment Plant 55-Hour Trihalomethane Concentrations for Each Scenario
Table 8. Pine Hills Water Treatment Plant Ozone Testing Scenarios
Ozone Demand Characteristics The average H2S concentration from the Pine Hills WTP operating wells was 0.64 mg/L. Continued on page 30 Florida Water Resources Journal • November 2014
29
Continued from page 29 For test scenario B1, the raw water was treated with an applied ozone dose of 2 mg/L (~0.1 mg/L ozone residual at SP 2). This represents an ozone-to-sulfide ratio of approximately 3.13:1. Table 8 shows the scenarios performed, the corresponding ozone dose, well flow, and ozone production for each scenario. The testing was performed in the order of B5, B1, B2, B3, and B4.
Figure 7. Pine Hills Water Treatment Plant Ozone Decay Tests (First Test)
Table 9. Pine Hills Water Treatment Plant Average Ozone Decay Coefficients
Ozone Decay Characteristics Before the decay tests were performed, the plant was operated at a steady applied ozone dose (depending on trial run) and flow (11.6 mgd) for a minimum of 30 minutes to obtain a steady ozone residual and dose for the raw water. For each scenario, the decay test was performed twice. Figure 7 shows the decay test results for the first test performed for each scenario.. The data show a logarithmic decay of the ozone residual in the water. The natural log of the ratio of measured ozone concentration to initial ozone concentration data were then plotted against time in order to get the decay coefficients at the various ozone-applied doses. The slope of the trend line of each of these scenarios is the decay coefficient for the ozone decay at each applied dose. Table 9 presents the average decay coefficients. The decay data show the ozone decay rate that will be utilized when designing the ozone system to prevent any possible ozone residual carry-over from the contactors to the ground storage tanks. Trihalomethane Formation Potential After each decay test was performed, and before changing the applied ozone dose for the next scenario, samples of the treated water were taken from the last sample point at the discharge of the contactor. This sample was then taken to the OUC water laboratory and an SDS test was performed to determine the THMFP of the treated water. Figure 8 shows the SDS results and Figure 9 shows a 48-hour THM concentration for each scenario. The data indicate that an additional 1.5-2.0 mg/L of applied ozone dose will yield a potential 5 µg/L reduction in THM formation. However, it is not efficient to apply this additional dose of ozone to the raw water for a marginal improvement to the THMFP when the water at this WTP has an already low THMFP.
Disinfection Byproduct Impacts
Figure 8 . Pine Hills Water Treatment Plant Trihalomethane Formation Potential for Each Scenario
30
November 2014 • Florida Water Resources Journal
The Pine Hills WTP has the highest water quality (lowest H2S, lowest TOC) out of all of the WTPs. Figures 8 and 9 show a minimal (5 µg/L) reduction of THMs, with an additional 1.5-2.0 mg/L applied ozone dose above the base dose. At the Conway WTP, the data at the 48hour time frame indicate that there is not an
advantage to applying more ozone to the raw water to reduce the THMFP of the treated water. In addition, when looking over the complete 96-hour time period for the SDS testing, the data show no impacts as the lines continually cross each other, indicating no consistent reduction in the THMFP of the water. At the Navy WTP, the 55-hour time frame data do show a 10-12 µg/L drop in THMFP with the additional 1 mg/L of ozone added to the water; however, this test was stopped after 41 hours and not allowed to proceed to 96 hours, like the other samples, due to the chlorine residual dissipating below 0.2 mg/L after 41 hours. The THM formation data collected during the testing period do not suggest a definitive criterion for applying additional ozone to the water for DBP control. The addition of ozone above the doses required for H2S oxidation does appear to have an impact on the THMFP of the raw water at the facilities. However, an accurate prediction of the impacts cannot be determined—only a possible trend that warrants further analysis. It is recommended to perform THMFP tests again at each plant after the systems have been upgraded to sidestream injection. The reduced ozone residual variability in the sampling system will improve operational control and more accurate testing results.
Figure 9. Pine Hills Water Treatment Plant 48-Hour Trihalomethane Concentrations for Each Scenario
Florida Water Resources Journal • November 2014
31
C FACTOR
An Expo, Testing, Teaching, and Meetings All Increase Water Knowledge Jeff Poteet President, FWPCOA he FWPCOA Region VIII has outdone itself once again! The region, along with the local chapters of FSAWWA (Region V) and FWEA (Southwest Chapter), put on the seventh Annual Water and Wastewater Expo, where several hundred people came to get their continuing education training. Along with the courses that were approved for both continuing education units (CEUs) and professional development hours (PDHs), was an exposition floor where vendors from all over the state came to show their wares. I would like to recognize the efforts of Cherie Wolter, Ron Cavalieri, Jason Sciandra, Justin Martin, Jon Meyer, Jack Green, Fred
T
32
Gliem, and all of the instructors and vendors who participated. Over 60 door prizes were handed out and the comments from the students, vendors, and those who passed through the floor show were outstanding. I am personally looking forward to next year’s event. The Florida Department of Environmental Protection (FDEP) Operator Certification Program (OCP) has temporarily stopped its computer-based testing services for drinking water, wastewater, and system operators. The contract with Applied Measurement Professionals (AMP), which permits FDEP to offer computer-based testing, expired on August 28 of this year. For those wanting to take the state exam, you may schedule a paper-and-pencil exam through the Department. The required form is available on the FDEP website and can be faxed to its office for the November and December dates. Once the Department has re-
November 2014 • Florida Water Resources Journal
ceived your location request, you will receive confirmation of the location, date, and time. For additional information please go to http://www.dep.state.fl.us/water/wff/ocp/index .htm, “Pencil-and-Paper Exam Frequently Asked Questions.” The FDEP is currently in the process of procuring a computer-based testing vendor in order to continue to offer the same level of testing services. The Department anticipates that the examination services will resume in January 2015. If you have questions, visit the OCP website or call the office at (850) 245-7500. The deadline for you to meet your educational requirement for license renewal is fast approaching. Some of us like to get those credits with hands-on training, some like the classroom setting, and others like to acquire those credits in the privacy and leisure of their own home. The FWPCOA can meet any of your water and wastewater educational needs in the setting that you prefer. Along with training from our local regions, the state will put on another state short school in March. Another great way of acquiring your CEU credits is by sharing your knowledge. The Association is divided into 13 regions, and their individual training programs, as well as our state programs, are always looking for good instructors. You are allowed to gain credit for the hours you teach and your involvement will benefit the entire industry. If you would like to share your knowledge with your industry in a local region, or at the state level, please visit our website or call the training office at (321) 3839690 for more information. By the time you read this message the November board of directors meeting will have already concluded. I’m hesitantly excited about the November meeting (actually being held in October), which will include the Rim Bishop Birthday Bash. I heard the last bash was reminiscent of a line from the movie Jaws: “Eleven hundred men went in the water; three hundred and sixteen men come out.” I’m going to try and stay out of the water. If I survive the bash I’ll be able to bore you all with at least one more article. As of now, I have not identified the location of the December board meeting; however, I will post it in my next article. I hope to see you soon!
Florida Water Resources Journal • November 2014
33
F W R J
Effects of Backwash Water and Chemical Addition on Biofiltration Hongxia Lei, Dustin W. Bales, and Maya A. Trotz he David L. Tippin Water Treatment Facility (Facility) is an advanced water treatment facility in Tampa, with a capacity up to 120 mil gal per day (mgd) consisting of coagulation, flocculation, sedimentation, ozonation, and biofiltration processes. The finished water has seasonally exhibited a very high chlorine/chloramine demand, up to 5 mg/L as chlorine, which has incurred a higher chemical cost. Previous research at this facility suggested that biofiltration is the culprit (Marda et al, 2008). The issue of high chlorine demand with ozone and biofiltration was also reported by Wilczak et al (2003) and Vokes (2007) and attributed to biofiltration not performing well. Biofiltration prevents regrowth in the distribution system by relying on bioactivity in the filters to consume biodegradable carbon, increasing the biostability of the finished water in the distribution system (Escobar et al, 2001; Urfer et al, 1997; Wang et al, 1995; Price et al, 1993; LeChevallier et al, 1992; Rittmann et al, 1989; Bouwer and Crowe 1988). When the nutrient molar ratio of 100:10:1 (carbon:nitrogen:phosphorus) required by heterotrophic bacteria is met, assimilable organic carbon (AOC) becomes the limiting factor of biofilm formation (LeChevallier et al, 1991). LeChevallier et al (1996) found a direct correlation between AOC and regrowth potential. As a single cause of increased chlorine/chloramine demand in biofiltration has not been identified, multiple avenues aiming at improving the postfilter chlorine/chloramine demand have been investigated. Amirtharajah (1993) examined the importance of the air scouring during the process of
T
filter backwash, where air and water were used simultaneously to create a phenomenon known as “collapse-pulsing.” A high-speed camera was used to confirm the theoretical basis of the method. Collapse-pulsing increases the detachment of particles during backwash, preventing mud-ball formation and increasing filter effluent quality after backwash. Ahmad et al (1998) found that collapsepulse backwashing, followed by traditional water backwash with at least 25 percent bed expansion, produced water with lower AOC than without air scouring. It also produced lower AOC than a nonbiological filter, and the type of filter backwash water impacts filter performance as well. Lower levels of AOC are associated with nonchlorinated backwash water (Ahmad et al, 1998). Overall, nonchlorinated water for filter backwash has provided many advantages over chlorinated water. The removal of aldehydes, AOC, and total organic carbon (TOC) is higher, while chlorine/chloramine decays more slowly (Vokes, 2007; Miltner et al, 1995; Wang et al, 1995). Granular activated carbon (GAC) generally performs better than anthracite for biofiltration. Ahmad and Amirtharajah (1998) found that bacteria remain better attached to GAC than anthracite during backwash. Not only could GAC hold three to eight times more biomass than anthracite, it also provides better aldehyde removal at colder temperatures and establishes biofilms quicker than anthracite (Urfer et al, 1997; Wang et al, 1995). Anthracite filter performance is negatively affected by chlorinated backwash water more significantly than GAC (Urfer et al, 1997).
Table 1. Water Quality of the Feed Water to the Pilot Plant
34
November 2014 • Florida Water Resources Journal
Hongxia Lei is the water quality assurance officer with City of Tampa; Dustin W. Bales is a graduate intern with City of Tampa from the University of South Florida in Tampa; and Maya A. Trotz is an associate professor at the University of South Florida in Tampa.
In multiple studies, organic carbon has been identified as the limiting nutrient for biofilm formation and regrowth in finished water and correlated with AOC formation (Chandy and Angles, 2001; LeChevallier et al, 1992; LeChevallier et al, 1991). Biofilm formation is more prominent in waters with increased chloramine decay rates (Chandy and Angles, 2001). LeChevallier et al (1991) identified the limiting nutrient molar ratio of 100:10:1 (carbon, ammonia-nitrogen, and orthophosphate-phosphorus) for biofilm formation. Based on this ratio, where biofilm development is being prevented, Lauderdale et al (2012) investigated the addition of nutrients to biofilters, where biofilm development is a positive trait. Carbon, nitrogen, and phosphorus were first quantified in prefiltration water. The NH4-N and PO4-P were determined to be the deficient nutrients and subsequently added to the top of the filters. The basis for this is twofold. For one, if sufficient nitrogen and phosphorus are not available, bacteria in the filters are not removing the maximum amount of biodegradable carbon. Secondly, bacteria produce more biofilm when “stressed,” meaning a nutrient in limited supply may increase the amount of biofilm material formed in the filters, leading to excessive clogging. Lauderdale et al (2012) also investigated the addition of hydrogen peroxide to provide microorganisms with increased dissolved oxygen and depolymerize the extracellular polymeric substances (EPS) and observed a 60 percent decrease in terminal headloss during the 10-day study. The primary materials of biofilm are EPS, with polysaccharides as one of the major components (Tsuneda et al, 2003). Liu et al (2006) identified the relationship between nutrients and microbial production and secretion of
EPS. Lauderdale et al (2012) found that nutrient addition decreased terminal head loss by approximately 15 percent, possibly attributed to less EPS. The significance and implications of soluble microbial products (SMPs) in wastewater treatment, of which EPS is a constituent, are well documented in a review published by Barker and Stuckey (1999). The SMPs are the assortment of organic products and byproducts from microbial reactions involved in biological treatment. While most SMP research is in wastewater treatment, it is likely that SMPs and EPS have effects that have not been quantified on biological filtration in drinking water treatment. Mauclaire et al (2004) studied the effect of EPS on slow sand filtration, attributing at least 7 percent of clogging to EPS, a greater percentage than that of particle deposition. The goal of this study was to examine the effects of nonchloraminated backwash water, nutrient addition, media type, and hydrogen peroxide addition on biologically activated filters to improve their operation at the Facility, which is currently backwashed by water drawn from the clearwells, with the chloramine level around 5 mg/L. This study encompasses extensive test results from a two-year period of pilot and full-scale investigations, a time frame much longer than most studies, which allowed more realistic technology transfer from pilot to full-scale. The filter performance under chloraminated and nonchloraminated backwash water was compared back-to-back and confirmed by cycling between chloraminated and nonchloraminated water, with each condition run over several months. Similarly, the chemical additions were run for an extended period of time (at least one month). Some of the findings from this study deviate from previously published literature and reflect the complexity of water treatment technology.
Materials and Methods Experimental Design The pilot plant filters used in this study, emulating the full-scale system at the Facility, take water directly from the full-scale plant after coagulation and ozonation and before biofiltration. As a result, the water quality of the feed water to the pilot plant does not vary as much as the raw water. Constituents relevant to this study are summarized in Table 1, covering the same time span of this study from May 2011 through December 2012. Four factors were evaluated for their potential efficacy in improving the performance of biofiltration utilizing the six 1×1 ft sq filters at the pilot plant. The detailed experimental matrix is summarized in Table 2. The first con-
Table 2. Summary of Experiments Performed to Study the Effects of Nutrient and Hydrogen Peroxide on Filter Performance
dition was media material, with anthracite1 (0.8 – 1.0 mm) placed in the first two filters labeled as anthracite #1 and #2 GAC2 (0.8 – 1.0 mm) and in the remaining four filters labeled as GAC #1, #2, #3, and #4, all at a depth of 24 in. of media atop 12 in. of sand3 (0.45 – 0.55 mm). These six filters had been in operation for several years, with the GAC media over two years old and the anthracite media acclimated for three months before this study. As a result, the adsorption removal of TOC was minimal. The second condition was the effect of chloramine present in backwash water. To test this condition, all six filters were run for three months with chloraminated backwash water, followed by five months of nonchloraminated backwash water, all at a filter loading rate of 1 gal per minute per sq ft (gpm/ft2). At that point, the backwash operation was automated, allowing higher loading rates to be tested with more frequent backwashes. To confirm the findings with a loading rate identical to a fullscale plant (typically about 2 gpm/ft2), the filters were switched back to chloraminated backwash water for two months and then nonchloraminated backwash water for four months. Filters were run for at least one month before any samples were collected to allow the bioactivity to recover whenever the backwash water was changed from chloraminated to nonchloraminated water. Both nutrient and hydrogen peroxide addition were studied with nonchloraminated backwash water, summarized in Table 2. With the DOC removal up to 1.5 mg/L, NH4-N (as ammonium chloride) and PO4-P (as phosphoric acid) were added at a dose of 0.351 mg/L and 0.078 mg/L, respectively, to anthracite #2, GAC #3, and GAC #4 from the top of these filters, allowing a direct performance
comparison between GAC and anthracite. This dose will meet the C:N:P molar ratio requirement of 100:10:1 with both N and P a little bit in excess to overcome the adsorption of N or P. Following nutrient addition, hydrogen peroxide was added from the top of the same three filers: anthracite #2, GAC #3, and GAC #4. During the course of each condition, samples were collected and tested for pH, temperature, chlorine demand, TOC, AOC, and carboxylic acids. Samples were taken from before and after the pilot filters, as well as from the full-scale system, allowing a comparison of performance. Pilot Plant The pilot filters were operated at loading rates of 1-2.5 gpm/ft2, with turbidity, headloss, and flow rate recorded to supervisory control and data acquisition (SCADA) software. Turbidity was measured by an online analyzer4 verified monthly and calibrated every three months; headloss and flow rate were also measured by online analyzers5,6 that were calibrated or inspected every six months. All other measurements were done by taking samples to the on-site water quality laboratory transported on ice in coolers. The GAC used in the pilot plant was acquired from the fullscale system after being in use for over two years and was already bioactive. Anthracite was acquired new and had not been previously used; therefore, the filters were run for three months prior to performing any tests. The three-month acclimation period was chosen based on findings reported by Velten et al (2011), which showed that bioactivity reached a plateau, based on DOC removal and adenosine triphosphate (ATP) analysis, after approximately two months. Continued on page 36
Florida Water Resources Journal • November 2014
35
Continued from page 35 Backwash water was stored in a 1,000 L high-density polyethylene (HDPE) tank. When chloraminated water was to be used for backwash, finished water from the clearwell of the full-scale Facility filled the tanks. When nonchloraminated water was to be used, effluent water from the pilot filters was collected and pumped into the tank. Nutrient addition was accomplished using a 120 L HDPE tank combined with a Cole-Parmer MasterFlex peristaltic pump, with the nutrients feeding into the top of the filters. The ammonia solution was prepared from ACS (American Chemical Society)-grade ammonium chloride (NH4Cl)7. The phosphorus solution was prepared from ACS-grade 85percent phosphoric acid7. Hydrogen peroxide addition was accomplished using the same system using ACS-grade 30-percent hydrogen peroxide8. When the project first started, filters were manually backwashed twice a week (Tuesday and Friday), with their headloss recorded immediately prior to backwash. Starting in December 2011, or eight months into studying the effect of chloraminated backwash water, the filters were put on an automatic backwash sequence identical to the one utilized for the full-scale Facility filtration system, using run time, turbidity, and headloss as the set points. All subsequent studies, including the confirmation tests for chloraminated and nonchloraminated backwash water and the impact of nutrient and hydrogen peroxide additions, were performed with automated filter backwash. The run time set point was changed from 80 hours to 120 hours in April 2012 to accommodate increased filter run time; it was further raised to 150 hours in May 2012. The backwash procedure consisted of first draining the filter water level to 1 ft above the media, followed by 90 seconds of air scouring at 3 standard cu ft per minute per sq ft (scfm/ft2). Low-rate backwash at 7 gpm/ft2 began in tandem with 45 seconds of air
scouring and continued for another 45 seconds, followed by 7 minutes of high-rate backwash at 17 gpm/ft2. High rate backwash is followed by 1 minute of low-rate backwash to finish the cycle and the filter is then put back in service. Analytical Methods Chlorine demand, measured by how fast the monochloramine would decay, was obtained in duplicate by dosing the waters with ammonia and chlorine sequentially at a 1.05:1 molar ratio of ammonia to chlorine, and later increased to 1.2:1 to avoid the potential breakpoint chlorination issues due to the ammonia deficiency. Monochloramine was used for the chlorine demand study to better simulate fullscale conditions, as this was the type of chlorine applied to the finished water for maintaining disinfectant residual. The target chloramine dose was 8 mg/L, with an adjusted pH of 7.70. This pH was selected to better simulate full-scale conditions. Total chlorine was measured 45 minutes after dosing. Following day one, total chlorine was measured daily at approximately the same time during the remaining four days by Standard Method 4500G-Cl Chlorine (Residual), diethyl-p-phenylenedamine (DPD) colorimetric method (Standard Methods, 2005). Chlorine used for dosing was prepared from a 5-6 percent hypochlorite solution7. Ammonia used for dosing was prepared from ACS-grade ammonium chloride7. Phosphate buffer solution and DPD indicator solution were purchased factory prepared8. Potassium iodide was prepared from ACS-grade potassium iodide7. The TOC was measured according to Standard Method 5310C ( Standard Methods, 2005)9. The AOC was analyzed following Standard Method 9217B ( Standard Methods, 2005) by an outside laboratory10. Three carboxylic acids, including acetate, formate, and oxalate, were analyzed according to an ionic chromatographic method reported by Peldszus et al (1996), Kuo (1998), and Kuo et al (1996),
Table 3. Total Carboxylic Acid Removal: Comparison of Chloraminated and Nonchloraminated Backwash Water
36
November 2014 • Florida Water Resources Journal
with minor modifications11. In summary, 20 mg/L mercury chloride was used as a preservative and a sample holding time of 17 days was adopted. Postozone samples were not aerated since ozone residuals were consistently close to nondetect. The calculated method detection limits (MDLs) were 3.7, 2.5, and 2.5 µg/L for acetate, formate, and oxalate, respectively. Carboxylic acid analysis beginning in May 2012 was performed by an outside laboratory12 using the same method and identical instrument. The EPS was analyzed in both backwash water and filter media for all six pilot plant biofilters. The media samples were extracted following a protocol published by Lauderdale et al (2011) to allow the differentiation of free and bound EPS, and quantified using the Dubois method (1956). This method quantifies polysaccharides, which are the dominant components of EPS. For filter backwash water, the procedure was similar to the EPS measurement on the media. Since the dislodging of biofilm was already accomplished during backwash, the sonication step was not needed. The backwash water was directly centrifuged and the supernatant analyzed for free EPS and pellet after centrifugation was extracted and analyzed for bound EPS with the same procedure previously mentioned. The media samples were taken from the top layer of the filters when the filters had a headloss between 4 and 6 ft to ensure similar conditions and similar stage of EPS development between backwash cycles. Immediately after the media samples were collected, the filters were forced to backwash to enable the collection of backwash water samples under similar conditions.
Results Effect of Nonchloraminated Backwash Water and Media Type Carboxylic Acid Removal At the full-scale Facility, finished water with a typical chloramine residual of around 5 mg/L is used to backwash filters, which was reported to possibly have a negative impact on biofilter performance (Miltner et al, 1995). Table 3 shows the total concentrations of the three carboxylic acids in the feed/influent and in the effluent water for both GAC and anthracite filters at the pilot plant. The carboxylic acid concentrations in the feed water varied greatly from 41 µg/L-C to 162 µg/L-C, most of which were removed by the biofilters, with the removal percentage consistently over 70 percent. For the same time period, the removal of carboxylic acids at the full-scale plant averaged Continued on page 38
Florida Water Resources Journal • November 2014
37
Figure 1. Chlorine Curves with Nonchloraminated Backwash and Filter Loading Rate of 1 gpm/ft2
Continued from page 36 at 82 ± 6 percent. Apparently, the GAC filters at the pilot plant achieved similar removals of carboxylic acids to the full-scale GAC filters, while anthracite consistently underperforms GAC throughout all conditions in regards to the removal of carboxylic acids. For both GAC and anthracite filters, nonchloraminated backwash water didn’t improve the removal of carboxylic acids, and the filter loading rates also did not result in any difference in removal. This could be attributed to the fact that the removals are fairly high with chloraminated backwash water and there is no room left for improvement with nonchloraminated water. The TOC removal showed similar trending (results not presented), but is overall lower than the removal of carboxylic acids, typically in the range between 18 to 45 percent. Chlorine Demand of Filter Effluent Chlorine demand for both influent and effluent of all the filters was another metric used to evaluate the impact of nonchloraminated backwash water and filter media on filter performance. The same set of water samples from Table 3 were first dosed with chloramine at the target concentrations and chloramine residuals were measured daily. Figure 1 shows the chloramine decay kinetics over a five-day period under one of the test conditions and Figure 2 shows the summary of chlorine demand for all the samples generated in Table 3; the chlorine demand during the same time period for full-scale filters is also presented in Figure 2 as a reference point. Note that in the figure, the full-scale filters were always backwashed with chloraminated water, with the filter loading rate fluctuated around 2 gpm/ft2 during the entire pilot study. The error bars in Figure 2 merely reflected water quality variation rather than the experimental error because they were averaged based on samples collected monthly over a three-month period for chloraminated backwash water
Figure 2. Comparison of Chloraminated and Nonchloraminated Backwash Water on Chlorine Demand With Different Filter Loading Rates
38
November 2014 • Florida Water Resources Journal
Figure 3. Impact of Chloramine in Filter Backwash Water on Filter Run Time (BW – Backwash)
and a five-month period for the switch of backwash water, as Figure 4. Effect of 0.45 µm Filter on Pilot Granular Activated nonchloraminated backwash discussed previously. Another lesCarbon Effluent Chlorine Demand water. son learned was the ability to recogResults in Figure 2 have nize the differences among the shown a pronounced effect of filters of identical conditions. Filters chloraminated backwash water GAC #3 and GAC #4 can be best on chlorine demand. When the used to demonstrate this point and filters were backwashed with despite the same conditions, GAC chloraminated water, the chlorine #4 consistently had much longer fildemand of the filter effluent at ter run time under all test condithe pilot plant was similar to the tions. In summary, all four GAC full-scale plant. Pilot GAC filters and both anthracite filters exhibited at the loading rate of 1 gpm/ft2 differences in filter run time to varperformed a little bit better than ious extents. As a result, it is full-scale filters, which treated strongly recommended that biofilwater at a loading rate of 2 tration be studied, at least in dupligpm/ft2. When the loading rate of cate. pilot plant was increased to 2 gpm/ft2, no difference in chlorine Mechanism of Filter Performance demand was observed between Improvement pilot GAC filters and the full-scale To elucidate the underlyfilters. Overall, anthracite media ing mechanism for improved filter perform significantly worse than performance, the effluent from one GAC with the difference between GAC filter was treated by 0.45 mithe two media more pronounced crometre (µm) filter and the differwhen the loading rate was inence in chlorine demand before and creased from 1 to 2 gpm/ft2. after filtration was studied under In contrast, under nonchlochloraminated and nonchloramiraminated filter backwash condinated filter backwash conditions. tions, with a filter loading rate of 1 gpm/ft2 filter run time (Figure 3), which was recorded The results are shown in Figure 4, normalized (Figure 1), all four GAC filters, as well as the after December 2011 when the pilot plant by initial concentration. two anthracite filters, exhibit similar chlo- began to be backwashed by the fully autoWhen nonchloraminated backwash water ramine decay kinetics and chlorine demand mated SCADA system. Figure 3 is presented was used, no discernible difference was noted despite different media and other differences following the temporal order and grouped by after the sample was treated by the 0.45 µm filobserved among the six filters, such as filter various testing conditions shown in the x-axis. ter. With chloraminated backwash water, the run time and removal of TOC and carboxylic In this figure, the pilot and full-scale plants 0.45 µm filtration decreased chlorine demand acids. This is also true for the 2.5 gpm/ft2 filter were operated with the same filter loading rate, significantly. On day 3, a 15 percent improveloading rate as demonstrated in Figure 2 the same backwash procedures, and same ment was observed, in contrast to the miniswhenever nonchloraminated water was used source water; however, the backwash water for cule difference when nonchloraminated water for filter backwash. In both cases, the chlorine full-scale always contained chloramine with was used for filter backwash. These results demands for pilot plants for both GAC and residual up to 5 mg/L, depending on the level have suggested that particles small enough to anthracite filter effluent were significantly in the clearwell where the backwash water was avoid being retained by the GAC but large lower than full-scale filter effluent, which was drawn. The pilot plant was initially back- enough to be stopped by a 0.45 µm filter is the washed with the same type of chloraminated explanation for the improved chloramine still backwashed with chloraminated water. In the full-scale plant, the chlorine de- water, as shown in Figure 3, and switched to decay. Marda et al (2008) observed the similar mand for filter effluent is higher than the in- nonchloraminated water to study the impacts. phenomenon with chloraminated backwash fluent; in other words, the biofiltration adds The improvement in filter run time for both water, but provided no solution to resolve this additional chlorine demand to the water being anthracite and GAC filters from nonchloram- issue. The results presented in Figure 4 clearly treated, which was undesirable and caused inated backwash water is significant. demonstrated that the nonchloraminated filNear the end of the test, anthracite and ter backwash water could help filters better reproblems to the distribution system’s water quality maintenance. Results in Figure 2 sug- GAC showed 70 percent and 84 percent im- tain particles larger than 0.45 µm and cut gest that this problem could be eliminated by provement, respectively, over full-scale filters, down chlorine demand. switching to nonchloraminated backwash on average. These results also suggest that it water and the resulted improvement will be takes time for biological activity to reach its Effect of Nutrient and Hydrogen Peroxide persistent regardless of the filter loading rate full potential. On day 18, after nonchlorami- Addition nated backwash, longer filter run time was aland media type. The purpose of nutrient and hydrogen ready observed and continued to increase over peroxide addition is to better manage bioacthe course of the entire testing period for tivity on the filter media and control the seFilter Run Time Lower chlorine demand is one benefit nonchloraminated backwash water. The si- cretion of EPS. To evaluate the benefits to the with nonchloraminated water for filter back- multaneous improvement in filter effluent Facility, both were studied at its pilot plant, but wash. Another benefit is a significant longer chlorine demand was noticed, as well as after Continued on page 40 Florida Water Resources Journal • November 2014
39
Continued from page 39 with different study criteria; more specifically, the removals of TOC and carboxylic acids, chlorine demand, and filter run time. Also studied were turbidity, head loss, and filter loading rate, which were continuously recorded by the online analyzers. Starting in May 2012, filters anthracite #2, GAC #3, and GAC #4 had ammonia chloride and phosphoric acid added to the top of the filters to test the effect of nutrient addition on biofilter performance. The dosed concentrations were based on DOC using the 100:10:1 C:N:P molar ratio identified by LeChevallier et al (1991) as the limiting ratios for biofilm formation in drinking water. Ammonia concentrations in the effluent of the six pilot filters were all below 0.1 mg/L, with the actual levels varying among the six filters, and the levels for ammonia added to the filters were not statistically higher than those without ammonia addition. Phosphorous concentrations in the effluent showed a different trending. They were all below 0.01 mg/L for the six pilot filters one month after three of the six filters were dosed with the nutrient. However, monitoring conducted two months later showed the phosphorous levels for nutrient treated filters averaged 0.016 mg/L versus less than 0.010 mg/L for filters without nutrient addition, apparently attributing to nutrient breakthrough. These results suggested that enough nutrients were dosed and any benefit from nutrient ad-
dition should show if such benefit does exist. Figure 5 shows the removal for TOC and carboxylic acids and the associated chlorine demand as a result of nutrient addition. For both GAC and anthracite filters, nutrient addition clearly had no effect on the removal of TOC and carboxylic acids, or chlorine demand. There may be a slight negative effect of nutrient addition on the removal of TOC and carboxylic acids for GAC media, but it is within statistical error. Additionally, no difference was observed in regards to filter head loss and filter run time. The results presented here failed to confirm the benefits reported by Lauderdale et al (2012). This is likely due to the complexity of the water treatment process, the different source water, and other unknown factors. Following the nutrient addition, hydrogen peroxide dosed at 1 mg/L and 2 mg/L was tested. Hydrogen peroxide of 1 mg/L was added for 70 days to filters anthracite #2, GAC #3, and GAC #4, while the rest of the filters had no addition and served as controls. The effects of hydrogen peroxide addition can then be evaluated by comparing the performance of anthracite #2 versus anthracite control, and GAC #3 and GAC #4 versus GAC controls. Afterward, hydrogen peroxide dose was increased to 2 mg/L and applied to the same three filters continuously for the following 34 days. No significant differences in TOC removal, carboxylic acid removal, or chlorine
Figure 5. Effect of Nutrient Addition on Total Organic Carbon Removal, Carboxylic Acid Removal, and Chlorine Demand
40
November 2014 • Florida Water Resources Journal
demand were observed for either anthracite or GAC media with either 1 or 2 mg/L hydrogen peroxide added. Filter run time is summarized in Figure 6. Because the tests were run over six months, source water was expected to change over the time period. As a result, controls were used to take into account changes in source water. For anthracite media, nutrient and hydrogen peroxide addition appears to have a positive effect on filter run time based on relative difference between the test and control filters; however, GAC does not exhibit the same results. The GAC #4 seems to be positively affected by either nutrient or hydrogen peroxide addition, but GAC #3 showed the opposite effect. The absolute filter run time of GAC #3 had increased when 1 mg/L hydrogen peroxide was added to the filter. However, when the relative ratio between GAC #3 and the GAC control (GAC #1 or 2) was compared, its performance stayed flat with nutrient and 1 mg/L hydrogen peroxide addition and became worse when hydrogen peroxide was fed at 2 mg/L. This illustrated again the importance of evaluating biofilters at least in duplicate to account for variations between filters. Overall, the improvement in filter run time from either nutrient or hydrogen addition is inconclusive for GAC media and a slight advantage is observed for anthracite media. This could be due to the better biological activity and retention exhibited by GAC filters Continued on page 42
Figure 6. Impact of Nutrient and Hydrogen Peroxide Addition on Filter Run Time
FWPCOA TRAINING CALENDAR SCHEDULE YOUR CLASS TODAY! NOVEMBER 3-6 ....Backflow Tester ........................................Deltona ............$375/405 17-20 ....Backflow Tester ........................................St. Petersburg ....$375/405 21 ....Backflow Tester Recert*** ........................Deltona ............$85/115
DECEMBER 1-3 ....Backflow Repair ........................................Deltona ............$275/305 15-19 ....Water Distribution Level 3, 2 ..................Deltona ............$275/305
UPCOMING 2015 CLASSES
JANUARY 12-15 ....Backflow Tester ........................................St. Petersburg ....$375/405 12-16 ....Reclaimed Water Field Site Inspector ....Deltona ............$350/380 23 ....Backflow Tester Recert*** ........................Deltona ............$85/115
FEBRUARY 9-12 ....Backflow Tester ........................................Deltona ............$375/405 27 ....Backflow Tester Recert*** ........................Deltona ............$85/115 Course registration forms are available at http://www.fwpcoa.org/forms.asp. For additional information on these courses or other training programs offered by the FWPCOA, please contact the FW&PCOA Training Office at (321) 383-9690 or training@fwpcoa.org. * Backflow recertification is also available the last day of Backflow Tester or Backflow Repair Classes with the exception of Deltona ** Evening classes
You are required to have your own calculator at state short schools and most other courses.
*** any retest given also Florida Water Resources Journal • November 2014
41
Continued from page 40 Implications to Full-Scale Plant (Ahmad et al, 1998), and as a reFigure 7. Effect of Nutrient and Hydrogen Peroxide Addition and Future Studies sult, there is not much room left on Extracellular Polymeric Substances Concentrations This study has revealed the for improvement. high variability of biofilter performin (a) Backwash Water and (b) Filter Media To help better understand ance, in spite of identical configurathe results and elucidate the reations and operational procedures. It sons for the observed difference is recommended that future studies from Lauderdale et al (2012), be conducted with duplicate or even EPS was monitored in filter triplicate filter columns, which is backwash water and on the challenging considering the scale and media. The results are summademanding nature of pilot testing. rized in Figure 7. In filter backYet, capturing and being able to forewash water, less than 15 percent see variability of biofilters is an imof EPS was present as unbound; portant and often neglected issue. on the media, EPS was still Each filter’s run time in this study not mostly bound, but the unbound only differs by up to 50 percent comEPS concentration became more pared to each other, it also varies by significant. These data have 20 to 30 percent between backshown EPS levels are greatly afwashes. It should be noted that defected by seasonal temperature spite the significantly different run changes. The relatively warmer time among the different filters, the month of August directly rechlorine demand and removal persulted in higher EPS, both in filcentages of TOC and carboxylic acids ter backwash water and on the were very close under identical conmedia, regardless of the media ditions. The data suggest that as run type. The seasonal difference was time increases, variance increases. Filmore pronounced in the pilot ter run time is very sensitive to variplant than the full-scale plant, ations in source water quality, with likely due to the fact that unlike extreme peaks and drops within the full-scale plant, the pilot short time spans compared to other plant used nonchloraminated metrics of filter performance. water for filter backwash and had Based on pilot plant study more bioactivity. results, the recommended resoluIn filter backwash water, nution for the high chlorine demand trient and hydrogen peroxide adproblem in finished water is to use dition did not cause any nonchloraminated water for filter difference to EPS concentrations. backwash. The estimated savings Despite the difference observed for chlorine and ammonia is about All samples were run in quadruplicate with errors less than 20 percent among the six filters, the EPS lev20 to 30 percent of their current els for the controls of both GAC cost, depending on time of the year and anthracite fell well within the same range in the unit of mg/L. In this study, nutrient ad- and water demand. Approximately one third as the testing filters. The GAC #4 did exhibit dition did not decrease EPS for GAC or an- of the savings is from ammonia and two thirds relatively higher EPS concentration in the thracite media when compared to the control from chlorine, depending on market prices. backwash water, which seems to be consistent groups, which explained the lack of improve- Additional savings should come from the with this filter’s exceptionally longer filter run ment in filter performance from the nutrient lower volume of backwash water required due time. For some reason, which could be better addition. Hydrogen peroxide addition, how- to longer filter run times. Collectively, these perforation in the supporting plate in the un- ever, did decrease EPS for GAC filters with add up to a total savings of around $270,000, derdrain system, this filter’s backwash appar- GAC #3 and #4 showing less EPS compared to assuming the cost to produce water remains ently is more efficient and removes more EPS. their corresponding control filters. around $500 per mil gal (MG). More imporDespite the improvement in EPS levels, tantly, the biofilters will be optimized and pose Overall, regardless of chemical additions, the level of EPS in backwash water seems to corre- the filters with hydrogen peroxide addition did less operational challenges, especially when late with filter run time and can be used as a not show longer filter run time (Figure 6) or dealing with the control of nitrification probrough indicator of the potential filter run time. less chlorine demand (Figure 5), nor did they lems at the furthest end of the distribution sysOn the media, as expected, higher levels show better removal of TOC and carboxylic tem. of EPS were observed on GAC when compared acids (Figure 5). Based on these results and the to anthracite. The levels of EPS on both media significant differences from previously pubConclusion are slightly higher than EPS on sand (Mauclaire lished literatures (Lauderdale et al, 2012), furThe performance of biofiltration was et al, 2004), but still within the same order of ther studies on nutrient and hydrogen magnitude. No direct comparison could be peroxide addition are strongly recommended studied using a multitude of factors, aiming at made with data reported by Lauderdale et al to include a more diversified coverage of geo- solving the high chlorine demand problem in finished water via filter optimization. Based on (2012), where EPS on the media was reported logical locations and source waters.
42
November 2014 • Florida Water Resources Journal
this study, increased bioactivity should be desired, as it can improve filter performance. The chloramine in the backwash water had a strong negative effect on the filter performance with respect to both chlorine demand and filter run time. A switch to nonchloraminated backwash water exhibited the most significant improvement on the biofiltration system out of all the factors studied, and subsequently led to the largest cost savings. Using nonchloraminated backwash water, the chlorine demand in filter effluent remained the same as the influent, representing a 50 percent improvement for anthracite and a 30 percent improvement for GAC when compared with chloraminated backwash water. The filter run time was increased by approximately 40 percent as a result of using nonchloraminated backwash water, which directly translated into a 40 percent decrease in backwash water usage. Altogether, switching to nonchloraminated water for filter backwash will result in an estimated annual cost saving of $270,000 once implemented at the full-scale Facility. Nonchloraminated backwash water did not show any significant effects on the removal of TOC or carboxylic acids. Generally, GAC media perform better than anthracite media, but anthracite still performs sufficiently well for many utilities to consider due to the significant cost difference between GAC and anthracite. This study showed no major effect from the addition of nutrient and hydrogen peroxide. Their potential benefit judged by the removal of TOC and carboxylic acids, chlorine demand of the effluent, and filter run time was very minor. Nutrient addition did not cause significant impact on EPS concentrations on the media. Hydrogen peroxide addition decreased EPS levels, but without any associated benefits. Higher levels of EPS were observed on GAC when compared to anthracite and in the relatively warmer summer month of August when compared to December. EPS in filter backwash water appeared to be a rough indicator of the effectiveness of backwash and subsequently affected filter run time.
Acknowledgements The authors kindly acknowledge the financial and staffing support from City of Tampa Water Department. Paula Lowe, Jon Docs, Niloofar Pishdad, Charles Ketter, and Jason Cohen at the David L. Tippin Water Treatment Facility provided assistance on various aspects of this study. The authors also thank Dr. James R. Mihelcic at the University of South Florida for his comments to this article. Continued on page 44 Florida Water Resources Journal • November 2014
43
Continued from page 43
Footnotes 1 2 3
4
5
6
7 8 9
10 11 12
Anthracfilter Inc., Niagara Falls, N.Y. ActiCarb, Dunnellon, Fla. Standard Sand & Silica Company, Davenport, Fla. HACH, model SC100 controller with a 1720E sensor, Loveland, Colo. Endress+Houser, model PMD70, Greenwood, Ind. Endress+Houser, magmeter Promag 10, Greenwood, Ind. Fisher Scientific, Fair Lawn, N.J. Sigma Aldrich, St. Louis, Mo. Teledyne Tekmar TOC Fusion, Thousand Oaks, Calif. MWH Laboratories, Monrovia, Calif. Dionex ICS 3000, Sunnyvale, Calif. Underwriters Laboratory, South Bend, Ind.
References • Ahmad, R. and Amirtharajah, A., 1998. Detachment of Particles During Biofilter Backwashing. Journal American Water Works Association, 90:12:74. • Ahmad, R.; Amirtharajah, A.; Al-Shawwa, A.; and Huck, P., 1998. Effects of Backwashing on Biological Filters. Journal American Water Works Association, 90:12:62. • Amirtharajah, A., 1993. Optimum Backwashing of Filters with Air Scour: A Review. Water Science & Technology, 27:180:195. • Barker, D. and Stuckey, D, 1999. A Review of Soluble Microbial Products (SMP) in Wastewater Treatment Systems. Water Research, 33:14:3063. • Bouwer, E. and Crowe, P., 1988. Biological Processes in Drinking Water Treatment. Journal American Water Works Association, 80:9:82. • Chandy, J. and Angles M., 2001. Determination of Nutrients Limiting Biofilm Formation and the Subsequent Impact on Disinfectant Decay. Water Research, 35:11:2677. • Dubois, M.; Gilles, K.; Hamilton, J.; Rebers, P.; and Smith, F., 1956. Colorimetric Method for Determination of Sugars and Related Substances. Analytical Chemistry, 28:3:350. • Escobar, I. and Randall, A., 2001. Assimilable Organic Carbon (AOC) and Biodegradable Dissolved Organic Carbon (BDOC): Complementary Measurements. Water Research, 35:18:4444. • Huck, P.; Fedorak, P.; and Anderson, W., 1991. Formation and Removal of Assimilable Organic Carbon during Biological Treatment. Journal American Water Works Association, 83:12: 69.
44
• Janssens, J.; Meheus, J.; and Dirickx, J., 1985. Ozone Enhanced Biological Activated Carbon Filtration and Its Effect on Organic Matter Removal, and in Particular on AOC Reduction. Water Science & Technology, 17:67:1055. • Kuo, C., 1998. Improved Application of Ion Chromatographic Determination of Carboxylic Acids in Ozonated Drinking Water. Journal of Chromatography A, 804:1: 265. • Kuo, C.; Wang, H.; Krasner, S.; and Davis, M., 1996. Ion-Chromatographic Determination of Three Short-Chain Carboxylic Acids in Ozonated Drinking Water. Water Disinfection and Natural Organic Matter: Characterization and Control (Minear, R.A. and Amy, G.L. editors), ACS Symposium Series, No. 649, American Chemical Society, Washington, DC. • Lauderdale, C. V.; Chadik, P.; Kirisits, M. J.; and Brown, J. C., 2012. Engineered Biofiltration: Enhanced Biofilter Performance Through Nutrient and Peroxide Addition. Journal American Water Works Association, 104:5 E298. • Lauderdale, C. V.; Brown, J. C.; Chadik, P. A.; and Kirisits, M. J. 2011. Engineered Biofiltration for Enhanced Hydraulic and Water Treatment Performance. Final report, Water Research Foundation, Denver. • LeChevallier, M.; Becker, W.; Schorr, P.; and Lee, R., 1992. Evaluating the Performance of Biologically Active Rapid Filters. Journal American Water Works Association, 84:4:136. • LeChevallier, M.; Schulz, W.; and Lee, R., 1991. Bacterial Nutrients in Drinking Water. Applied & Environmental Microbiology, 57:3:857. • LeChevallier, M.; Welch, N.; and Smith, D., 1996. Full-Scale Studies of Factors Related to Coliform Regrowth in Drinking Water. Applied & Environmental Microbiology, 62:7:2201. • Liu, J.; Liu, C.; Edwards, E.; and Liss, S., 2006. Effect of Phosphorus Limitation on Microbial Floc Structure and Gene Expression in Activated Sludge. Water Science & Technology, 54:1:247. • Marda, S.; Kim, D-I.; Kim, M-J.; Gordy, J.; Pierpont, S.; Gianatasio, J.; Amirtharajah, A.; and Kim, J-H., 2008. Plant Conversion Experience: Ozone BAC Process Installation and Disinfectant Residual Control. Journal American Water Works Association, 100:4:117. • Mauclaire, L.; Schurmann, A.; Thullner, M.; Zeyer, J.; and Gammeter, S., 2004. Sand Filtration in a Water Treatment Plant: Biological Parameters Responsible for Clogging. Aqua, 53:93. • Miltner, R.; Summers, R.; and Wang, J., 1995. Biofiltration Performance: Part 2, Effect of
November 2014 • Florida Water Resources Journal
•
•
•
•
•
•
•
•
•
•
•
•
•
Backwashing. Journal American Water Works Association, 87:12:64. Peldszus, S.; Huck, P.; and Andrews, S., 1996. Determination of Short-Chain Aliphatic, Oxo-and Hydroxy-Acids in Drinking Water at Low Microgram per Liter Concentrations. Journal of Chromatography A, 723:1:27. Price, M.; Bailey, R.; Enos, A.; Hook, M.; and Hermanowicz, S., 1993. Evaluation of Ozone/Biological Treatment for Disinfection Byproducts Control and Biologically Stable Water. Ozone: Science & Engineering, 15:2:95. Rittmann, B.; Huck, P.; and Bouwer, E., 1989. Biological Treatment of Public Water Supplies. Critical Reviews in Environmental Control, 19:2:119. Standard Methods for the Examination of Water and Wastewater, 2005 (21st ed.). APHA, AWWA, and WEF, Washington. Tsuneda, S.; Aikawa, H.; Hayashi, H.; Yuasa, A.; and Hirata, A., 2003. Extracellular Polymeric Substances Responsible for Bacterial Adhesion onto Solid Surface. FEMS Microbiology Letters, 223:2:287. Urfer, D.; Huck, P.; Booth, S.; and Coffey, B., 1997. Biological Filtration for BOM and Particle Removal: A Critical Review. Journal American Water Works Association, 89:12:83. van der Kooij, D.; Hijnen, W.; and Kruithof, J., 1989. The Effects of Ozonation, Biological Filtration and Distribution on the Concentration of Easily Assimilable Organic Carbon (AOC) in Drinking Water. Ozone: Science & Engineering, 11:3:297. van Der Kooij, D.; Visser, A.; and Hijnen, W., 1982. Determining the Concentration of Easily Assimilable Organic Carbon in Drinking Water. Journal American Water Works Association, 74:10:540. Velten, S.; Boller, M.; Koster, O.; Helbing, J.; Weilenmann, H.; and Hammes, F., 2011. Development of Biomass in a Drinking Water Granular Active Carbon (GAC) Filter. Water Research, 45:19:6347. Vokes, C., 2007. Impact of Ozone and Biological Filtration on Water Quality Parameters in Arlington, Texas. Ozone: Science & Engineering, 29:4:261. Wang, J.; Summers, R.; and Miltner, R., 1995. Biofiltration Performance: Part 1, Relationship to Biomass. Journal American Water Works Association, 87:12:55. Westerhoff, P.; Debroux, J.; Aiken, G.; and Amy, G., 1999. Ozone-Induced Changes in Natural Organic Matter (NOM) Structure. Ozone: Science & Engineering, 21:6:551. Wilczak, A.; Hoover, L.; and Lai, H., 2003. Effects of Treatment Changes on Chloramine Demand and Decay. Journal American Water Works Association, 95:7:94.
Operators: Take the CEU Challenge! Members of the Florida Water & Pollution Control Association (FWPCOA) may earn continuing education units through the CEU Challenge! Answer the questions published on this page, based on the technical articles in this month’s issue. Circle the letter of each correct answer. There is only one correct answer to each question! Answer 80 percent of the questions on any article correctly to earn 0.1 CEU for your license. Retests are available. This month’s editorial theme is
Water Treatment. Look above each set of questions to see if it is for water operators (DW), distribution system operators (DS), or wastewater operators (WW). Mail the completed page (or a photocopy) to: Florida Environmental Professionals Training, P.O. Box 33119, Palm Beach Gardens, FL 33420-3119. Enclose $15 for each set of questions you choose to answer (make checks payable to FWPCOA). You MUST be an FWPCOA member before you can submit your answers!
___________________________________________ SUBSCRIBER NAME (please print)
Article 1 ________________________________________ LICENSE NUMBER for Which CEUs Should Be Awarded
Article 2 ________________________________________ LICENSE NUMBER for Which CEUs Should Be Awarded
If paying by credit card, fax to (561) 625-4858 providing the following information:
Earn CEUs by answering questions from previous Journal issues!
___________________________________________
Contact FWPCOA at membership@fwpcoa.org or at 561-840-0340. Articles from past issues can be viewed on the Journal website, www.fwrj.com.
___________________________________________
Treatment of Organic-Laden Surface Water for Total Organic Carbon Steven J. Duranceau (Article 1: CEU = 0.1 DS/DW)
1. The Stage 1 and 2 D/DBPR applies to all community and nontransient water systems delivering water disinfected by any agent other than a. chlorine. b. Monochloramine. c. ultraviolet light. d. chlorine dioxide. 2. In the lime softening process, removal of _____________ is typically optimized at pH 10.3. a. natural organic matter (NOM) b. total activated carbon (TOC) c. color d. calcium hardness 3. In conventional treatment, ____________ must follow _____________ to remove additional color, TOC, and disinfection byproducts (DBPs). a. pH adjustment, filtration b. coagulation, softening c. disinfection, aeration d. coagulation, filtration 4. The analytical method used in measuring dissolved organic carbon includes which of the following steps not taken when measuring total organic carbon? a. Removing inorganic carbon b. Oxidizing remaining carbon to carbon dioxide c. Measuring carbon dioxide d. Sample filtration 5. To comply with regulatory locational running annual average maximum contaminant levels for total trihalomethane concentration, the author recommends a peak total trihalomethanes (TTHM) target concentration of ___ mg/l. a. 40 b. 30 c. 64 d. 48
(Credit Card Number)
(Expiration Date)
Disinfection Byproduct Formation Potential Reduction and Hydrogen Sulfide Treatment Using Ozone Greg Taylor, Charles DiGerlando, and Christopher Schulz (Article 2: CEU = 0.1 DS/DW)
1. The Orlando Utility Commission (OUC) ozone generation equipment uses __________ as feed gas. a. carbon dioxide b. liquid oxygen c. ammonia d. nitrogen 2. Which of the following is a recommendation made following this study? a. A feed rate exceeding H2S demand by 2 mg/L should be implemented. b. Trihalomethane formation potential (THMFP) should be run again after sidestream injection is implemented. c. No further study is required. d. The study should be expanded to investigate the effectiveness of combining ozone and chloramination. 3. Of the facilities studied, the ________________ Water Treatment Plant was determined to have the highest quality raw water. a. Pine Hills b. Disney c. Conway d. Navy 4. For the purposes of this study, the base dose of ozone is the amount that produces an ozone residual concentration of ____ mg/L. a. 0.1 b. 0.5 c. 1.0 d. 2.0 5. Sodium hypochlorite was added to the water to produce a chlorine residual of ___ mg/L after 96 hours as part of the simulated distribution system test. a. 0.1 b. 0.2 c. 0.5 d. 1.0 Florida Water Resources Journal • November 2014
45
F W R J
Treatment of Organic-Laden Surface Water for Total Organic Carbon Steven J. Duranceau any drinking water plants use water from rivers, reservoirs, or lakes as their raw water sources. These surface waters invariably contain some levels of pathogens that must be inactivated prior to distribution, as well as organic material (such as decaying plant matter). To ensure that water is safe to drink, the U.S. Environmental Protection Agency (EPA) mandates that a sufficient quantity of disinfectant be added to generate a residual concentration at the customer’s tap. Disinfectants can react with the organic material in drinking water to form disinfectant byproducts (DBPs), and epidemiological studies have identified that certain classes of DBPs are human carcinogens. The DBPs form when water that contains total organic carbon (TOC), also referred to as natural organic matter (NOM), is mixed with certain forms of chlorine. The DBP precursor compounds are a subset of NOM and are found in natural waters. The NOM is most commonly found in surface water where organic matter frequently enters the water body from runoff, and also from aquatic organisms. Public water systems using surface water must disinfect the water prior to delivery to the first customer.
M
What is Total Organic Carbon? The amount of carbon bound in an organic compound is known as TOC and is often used as a nonspecific indicator of water quality. With passage of EPA’s Safe Drinking Water Act, TOC analysis emerges as a quick and accurate alternative to the classical biochemical oxygen demand (BOD) and chemical oxygen demand (COD) tests traditionally reserved for assessing the pollution potential of wastewaters. The TOC is determined by removing inorganic carbon, oxidizing the remaining carbon to carbon dioxide using combustion or chemical oxidation with persulfate, and measuring the carbon dioxide produced using a conductivity detector or nondispersive infrared detector. Dissolved organic carbon (DOC) is determined similarly to TOC, but the sample is filtered through a 0.45 µm filter prior to oxidation. The ultraviolet absorbance (UVA) is measured by filtering a sample with a 0.45 µm filter and measuring absorbance at 254 nm. The specific ultraviolet absorbance (SUVA) is calculated by dividing UVA by DOC and multiplying by an appropriate unit correction factor. Surface waters are found to contain appreciable amounts of TOC, and the removal
Steven J. Duranceau, Ph.D., P.E., is associate professor and director, ESEI, department of civil, environmental, and construction engineering, at the University of Central Florida in Orlando.
of color and DBPs can be related to TOC removal. The natural organic content of Florida surface water is typically high, with TOC values often greater than 15 mg/L and true color values as high as 700 platinum-cobalt units (PCU). Historically, surface water treatment facility costs and performance decision making procedures were primarily based on turbidity and pH. With the implementation of EPA’s Stage 2 DBP Rule, TOC must now be integrated into the decision making process when it comes to treatment selection processes. Figure 1 illustrates a representation of humic acid, a DBP precursor, and one component of natural organic matter. Instead of volumetric size, NOM is commonly characterized by molecular weight (MW), molecular weight fractionation, and resin isolation into hydrophobic, intermediate, and hydrophilic fractions (Fabris et al, 2008; Kim et al, 2010). Polysaccharides and peptidoglycans are considered high MW compounds, whereas aromatics (i.e., lignin and tannin derivatives) are abundant in the intermediate-high MW fractions of NOM. Nonhumic, aromatic and aliphatic amines, amino acids, polysaccharides, and proteins are considered hydrophobic low molecular weight compounds.
Regulatory Considerations
Figure 1. Representative Structure of Humic Acid, a Component of Total Organic Carbon Source: Stevenson (1994)
46
November 2014 • Florida Water Resources Journal
Regulations drive the need to treat organic-laden surface waters. In December 1998, EPA published the Stage 1 Disinfectant/Disinfection Byproducts Rule (D/DBPR) that established treatment techniques for the control of precursors to disinfectant byproducts. This section requires enhanced coagulation or enhanced softening to remove a certain percentage of organic carbon based on the source water’s TOC and alkalinity for all public water systems using surface water or groundwater
under the direct influence of surface. In January 2006, EPA published the Stage 2 D/DBPR that required water utilities to comply with a reduced maximum contaminant level (MCL) of 80 µg/L for total trihalomethanes (TTHMs: chloroform, bromoform, and dibromochloroand dichlorobromo-methane) and a new MCL of 60 µg/L for the sum of five haloacetic acids (HAA5: monochloro-, dichloro-, trichloro-, monobromo, and dibromo-acetic acid) at each individual monitoring location in a distribution system (i.e., locational running annual averages). The rule sets up several alternatives to removal, one of which is SUVA of source or finished water. The SUVA is an analysis of water that uses UV absorbance and DOC levels. Previous studies established a relationship between SUVA and the levels of humic substances that are removed during enhanced coagulation and/or enhanced softening. If SUVA levels meet certain requirements, it is logical for the enhanced coagulation or softening to be unnecessary. Stage 1 D/DBPR allows an exemption from costly TOC removal requirements if SUVA levels for source or finished water are below 2.0 L/mg-m. It also provides for SUVA-level substitutions when calculating TOC removal compliance. The EPA has set required TOC removal levels for water systems that use conventional treatment, as shown in Table 1. Water systems that use surface water and conventional filtration treatment are required to remove specified percentages of organic materials, measured as TOC, that may react with disinfectants to form DBPs. Removal is to be achieved through a treatment technique (enhanced coagulation or enhanced softening). Enhanced coagulation has been identified as one of the most effective treatment methods for lowering TOC concentrations, and subsequently, DBP formation potential. As a result of the D/DBP Rule, there has been increasing emphasis by the water community on the removal of NOM from water supplies; important NOM removal options are coagulation, granular activated carbon (GAC) adsorption, membrane filtration, and anion exchange. Of these processes, coagulation is the most widely used in the water industry. But, when coagulation cannot remove adequate concentrations of NOM so that DBPs can be controlled, other treatment technologies, such as GAC, nanofiltration, and anion exchange may need to be used. Chemical softening has been used with variable success. Also, ozone and advanced oxidation may also be utilized, but typically must be combined with another unit operation.
Table1. Required Total Organic Carbon Removal Requirements for Conventional Treatment Plants1, 2 Source: EPA, June 2001. Stage 1 Disinfectants and Disinfection Byproducts Rule Fact Sheet. EPA 816-F-01-014
Total Organic Carbon Removal by Softening Removal of NOM is significant to the drinking water community in that color, TOC, and DBPs are NOM subsets and controlled by water treatment due to regulatory and/or aesthetic constraints. Not all NOM or TOC produces color or regulated DBPs; hence, TOC is a more universal measure of organic material in drinking water. Most if not all of the TOC removed during lime softening is in the form of nonpurgeable dissolved organic carbon (NPDOC). The TOC can be in a suspended or gaseous form in some drinking water sources; however, these TOC forms are either easily removed during drinking water treatment or are not DBP precursors, which prior to disinfection are in the form of NPDOC. Bench-scale tests demonstrate the importance of magnesium hydroxide precipitation and NOM characteristics on precursor removal by softening. The maximum percentage TOC removal achieved for lime and soda ash dosages evaluated for nine waters examined ranged from 23 to 50 percent (Thompson, 1997). Investigators have found that softening removed TOC, but was less effective for TOC removal than coagulation; addition of coagulants during softening enhanced TOC removal and the chemical structure affected TOC removal. A survey of water treatment plants participating in the information collection rule (ICR) found that 30 to 40 percent of TOC was removed during lime softening in the 2=4 mg/L and 4-8 mg/L TOC groups, respectively. They suggested additional TOC removal should not be required by regulation after 0.2 meq/L Mg removal, 0.8-1.2 meq/L alkalinity removal, or if major changes of existing facilities were required to accommodate the more slowly settling magnesium hydroxide, or
Mg(OH)2, floc, or the additional sludge (Clark and Lawler, 1996). Increasing doses of ferric sulfate to 9.5 mg/L Fe+3 were observed to increase TOC removal to 75 percent, as softening pH increased to 10.3 (Quinn et al, 1992). Bench-scale jar testing using waters from nine utilities found that TOC removal was correlated with increasing TOC concentration, hydrophobic TOC fraction, and the magnesium removed during softening. A significant relationship between the TOC removed and magnesium removed was observed (Thompson et al, 1997). Softening of Mississippi River water was found to remove less TOC than coagulation, although higher molecular weight hydrophobic organic solutes were removed by both processes (Semmens and Staples, 1986). Liao and Randtke (1986) suggested coprecipitation was the primary mechanism for removal of organic solutes during softening, and organic removal was limited to anionic compounds, which could absorb onto calcium carbonate (CaCO3) solids.
Calcium and Magnesium Precipitation During lime softening, calcium removal due to CaCO3 precipitation increases with pH to pH 10.3. At pH 10.3, nearly all of the calcium or carbonate alkalinity has been precipitated as CaCO3 because of equilibrium (K2, Ksp). Removal of calcium hardness is typically optimized at pH 10.3 in lime softening. Past pH 10.3, there is not enough carbonate alkalinity to precipitate the calcium solubilized from lime. Some slight additional calcium removal will be realized in a caustic softening process, but typically the vast majority of CaCO3 precipitation is complete at pH 10.3. Because of Mg(OH)2 equilibrium, adequate magnesium removal is typically not achieved Continued on page 48
Florida Water Resources Journal • November 2014
47
Continued from page 47 until pH ≼ 10.8. The exact pH for optimized CaCO3 and desired Mg(OH)2 precipitation may differ slightly from 10.3 and 10.8 due to calcium and magnesium interactions with other solutes. However, CaCO3 and Mg(OH)2 precipitation occurs in different pH ranges and can be related to TOC removal. The EPA and Water Research Foundation have investigated the removal of color, TOC, and DBP precursors (Taylor, 1984; Taylor, 1986; Randtke, 1999). The studied waters vary from a soft water with low magnesium content and low TOC concentration (Lawrence, Kan.) to a hard water with high magnesium content and high TOC concentration (Grand Forks, N.D.). The TOC varied directly with both calcium and magnesium hardness for these three waters and the TOC removal increased with pH for each. Prior to pH 10.3, the TOC removal varies from approximately 20 to 30 percent. The initial total hardness reduction of approximately 50 percent at pH 10.3 is due to CaCO3 precipitation and occurs simultaneously with 20 to 30 percent TOC reductions. Past pH 10.3 TOC reduction is increased by approximately 25 percent and is associated with approximately 30 percent reduction of initial total hardness, which is due to Mg(OH)2 precipitation. The TOC removal due to CaCO3 precipitation was limited to 30 percent and the TOC removal was increased to 55 percent when Mg(OH)2 was precipitated, which indicates that removal of magnesium hardness in a softening process will increase TOC removal.
Typically, magnesium coagulation at pH 11.3 to 12.0 accompanied 80 to 98 percent color removal, 20 to 40 percent TOC removal, and 40 to 65 percent trihalomethane formation potential (THMFP) removal. Optimum THMFP reduction was always accompanied by optimum TOC and color reduction (Taylor, 1984). Alum used as a coagulant aid at pH 11.5 increases THMFP, TOC, and color removal by about 10 percent. Enhanced coagulation and enhanced softening were developed specifically for conventional filtration treatment systems where rapid mix and flocculation were followed by gravity sedimentation; this is the normal treatment scheme for most surface water plants. However, some plants that do not use this conventional scheme can be adversely affected by practicing enhanced coagulation or enhanced softening, as these treatment techniques were not intended to be utilized in nonconventional filtration treatment systems. For example, some systems do not use gravity sedimentation for particulate removal; instead, liquid alum and a polymer chemical are dosed at optimum conditions to create pin floc, which is removed through a pressurized clarifying filter. Enhanced coagulation in this treatment scheme could easily lead to floc particle formation larger than what the system is designed to filter. Prematurely clogged filters and shorter filter runs are likely to result under enhanced coagulation conditions. Similar operating problems are anticipated for other forms of alternate treatment technologies or filtration systems.
Coagulation
Granular Activated Carbon
Coagulation is a treatment process that includes chemical addition, rapid mixing, and flocculation. The TOC removal can be influenced by the type of coagulant dosage, pH, mixing, water quality change, and the order of chemical addition. Maximum TOC removal tends to occur at pH values between 5 and 6 and low alkalinity water may require the addition of lime to maintain the pH in this range. Full-scale treatment plants have demonstrated that moving the location of the disinfection process to a point following coagulation and sedimentation, or modifying the coagulation process for increased removal of organic materials (or both), can result in substantial reductions in DBP formation. Coagulation can be an effective pretreatment technique subsequent to GAC or membrane filtration in that it removes particles that might clog GAC beds, which reduces the frequency of carbon regeneration and replacement, and it removes TOC, notorious for shortening membrane lives.
The EPA has identified the best available technology (BAT) for achieving compliance with the maximum contaminant levels for both TTHMs and HAA5 as treatment with GAC having a 10-minute empty bed contact time (EBCT) and a 180-day replacement frequency with chlorine as the primary and secondary residual disinfectant. The GAC adsorption is an effective technology employed for the removal of NOM, and is typically used as a medium as a filter-adsorber in many water treatment plants (Babi et al, 2007). Normally, 80 to 90 percent of the NOM measured in raw water sources can be removed by GAC adsorption (Roberts and Summers, 1982; Karanfil et al, 2007). Research by Owen and colleagues (1998) has shown that rapid smallscale column tests (RSSCTs) can be successfully used to predict NOM breakthrough-behavior GAC columns in terms of TOC and UV 254; additionally, it has been determined that several RSSCTs should
48
November 2014 • Florida Water Resources Journal
be performed with differing batches of influent waters that represent the seasons of interest. The GACs with large surface areas and pore volumes in pores >1 nm and basic pHPZC values should be selected for DBP precursor control. Removal of high molecular weight NOM during conventional treatment processes prior to filtration significantly increases the operational time of GAC for DBP formation control. Therefore, the impact of conventional treatment processes on GAC adsorption and DBP formation control should be evaluated in designing and operating GAC adsorption systems.
Membranes Membrane processes have been demonstrated to effectively and economically remove DBP precursors in water containing high concentrations of organic matter. There are four kinds of membranes: reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF). Table 2 presents an overview of TOC and DBP precursor removal using membranes. In general, membranes with a molecular weight cutoff (MWCO) of less than 1,000 daltons are necessary to remove substantial levels of NOM (Taylor, Thompson, and Carwell, 1987); a MWCO of less than 500 is usually necessary to reject greater than 90 percent of DBP precursors (Duranceau and Taylor, 2010; Metsamuuronen et al, 2014). Low pH and high ionic strength can decrease the apparent molecular size of organic matter and its electrostatic repulsion from the membrane surface and then decrease its removal. Bromide has been shown to have a significant effect on the formation of DBPs after chlorination of membrane permeates; in general, its removal by membranes is 20 to 70 percent. As the membrane MWCO decreases, the TOC removal increases. The resulting increase in the bromide-to-TOC ratio favors the formation of brominated DBPs after chlorination. However, if enough of the TOC is removed by the membrane, the absolute concentrations of the DBPs will be limited, regardless of relatively high bromide levels. Yoon and researchers (2005) have reported significant NOM removal of 70 to 86 percent with hydrophobic polyethersulfone (PES) and sulfonated PES membranes, although less than 10 percent rejection would have been expected when the average MW of NOM and membrane pore sizes is considered. This is attributed to hydrophobic interaction and electrostatic exclusion between the hydrophobic and charged membrane surface and the NOM molecules. The NF membranes are able to remove
compounds from macromolecular size to multivalent ions, but at higher transmembrane pressure as compared to UF. Almost complete NOM rejections were achieved with NF membranes having cut-off values in the range of 100–400 daltons (Duranceau and Taylor, 2010). However, NF is more susceptible to fouling when treating surface water supplies, as was noted by Reiss and colleagues (1999). Because of the larger pore sizes (0.005 to 5µm), the removal of NOM with MF and UF is substantially less than that observed with either NF or RO. By polypropylene 0.2µm MF membrane, it demonstrated a 15 percent removal of TOC and total THMFP from a flowing stream. By 0.05µm ceramic tubular membrane on blended river waters with an average TOC concentration of 8.2mg/L, it was reported reduced to approximately 30 percent removal of TOC and the THMFP was reduced by 10 to 20 percent by both the 0.05µm and 0.2µm ceramic tubular membrane. The removal of DBP precursors can be improved by the feedwater pretreatment of UF and MF. The two most common types of pretreatment are coagulant and polyaluminum chloride (PAC) addition. Using MF, with the addition of 10 to 15 mg/L of ferric chloride, the removal of THMFP from surface water could be increased from 15 to 60 percent. Using 0.05µm ceramic tubular membranes, the removal of TOC was from 30 to 60 percent and the removal of THMFP improved approximately 30 percent. Table 3 lists TOC removals for treatment using adsorbents such as PAC or iron oxide particles in combination with MF and UF.
Table 2. Summary of Trihalomethane Formation Potential Removal by Membrane Technology, Water Source, and Pretreatment
Anion Exchange The NOM in water contains significant amounts of high-molecular-weight soluble and colloidal humic and fulvic acid anions, which are often associated with the soluble and colloidal iron, manganese, and silica in the water. In the 1960s, macroporous weak-base anion (WBA) resins were used to remove color from river water, and in the 1970s, macroporous strong-base anion (SBA) resins were used to successfully treat highly colored groundwater. Also in the 1970s, polyacrylic strong-base resins were developed, which were less prone to irreversible fouling compared with the standard polystyene resins in universal use. Following the discovery of the formation of THMs and other DBPs in water in the mid-1970s, various strong- and weak-base anoin exchange resins were found to be capable of removing DBP precursors from water. Experimental use of resins for TOC removal Continued on page 50
Table 3. Removal of Total Organic Carbon by Ultrafiltration and Microfiltration with Adsorbent Pretreatment
Table 3 Notes: MF=microfiltration PAC=powered activated carbon
UF=ultrafiltration IOP=iron oxide particles
Florida Water Resources Journal • November 2014
49
Continued from page 49 continued through the mechanism of NOM removal by strong-base resins. Magnetic ionexchange resins have emerged as an effective method for treating surface water for organic matter (Comstock and Boyer 2014; Drikas et al, 2011; Mergen et al, 2008). In slightly acidic, neutral, and alkaline water, the acidic functional groups on NOM are negatively charged. Thus, TOC molecules are naturally attracted to anion exchange resins, which contain positively charged amine functional groups attached to a polystyrene or polyacrylic polymer matrix. Karpinska and colleagues (2013) have shown that a proprietary resin (MIEX) can remove over 89 percent of the DOC from the surface water. Anion exchange has been used to remove DOC and hardness simultaneously (Phetrak et al, 2014; Apell and Boyer, 2014). Weak-base anion resins contain weakly basic-primary, secondary, or tertiary aminefunctional (exchange) groups, which are positively charged (protonated) only in acidic solution. These resins function as anion exchangers only when the solution is pH ≤ 6. When pH is above 6, the amine functional groups are neutral and do not exchange ions. But, some WBA resins can function as adsorbents for TOC at pH ≥ 6. Strong-base anion resins contain quaternary amine functional groups typically attached to a polystyrene or polyacrylic matrix. The more common macroporous polyacrylic resin types, unlike the microporous polystyene resin types, are often used because of their lower organic fouling potential. Both resins have quaternary amine functional groups that are ionized (positively charged) and function as anion exchangers throughout the 3 to 13 pH range. Regarding porosity, macroporous resins have measurable Brunauer-Emmett-Teller (BET) surface area (measured by N2 adsorption), whereas microporous (or gel) resins have no measurable BET surface area. In aqueous solution, both types of resins have apparent porosity because they are swollen with water and readily allow hydrated ions to enter the hydrated polymer (Singer, 1999). Compared with GAC, WBA, or SBA, resins have greater sorption capacity for NOM, remove NOM faster, and are easier to regenerate (Boening, Beckman, and Snoeyink, 1980). When operated at pH 6.5 to 8.5, the WBA resins adsorb the NOM, whereas SBA resins operate by the mechanism of ion exchange. Various studies reported by Singer (1999) have demonstrated that it is not possible to reliably predict THMFP removal based on the surrogates of color or TOC removal.
50
Ozone Oxidation Ozone has been used in the treatment of drinking water since the end of the 19th century (Langlas, Reckow, and Brink, 1991). Although the original applications of ozone were disinfection, as experience increased, and since the mid-1970s, ozone has also been recognized as an important tool in controlling halogenated DBPs. Ozone is powerful and can react with many organic and inorganic solutes in water. By preozonation, followed by chlorination at low pH, it can reach the greatest net decrease in THM formation (Singer, 1999). High bicarbonate concentration can also help to improve THM control by ozone. Because ozone itself can decompose to form secondary oxidant species, one of which is hydroxyl radical (•OH), bicarbonate can act as a free radical scavenger that consumes hydroxyl radicals; then, the decomposition of ozone is slowed down, and the chance of solutes reacting with ozone is increased. On the other hand, with the reaction of hydroxyl radicals, bicarbonate can form bicarbonate radicals, which are more moderate radicals and may help to destroy DBP precursor sites (Malley, Edzwald, and Ram, 1986; Legube et al, 1985). Weiner (1995) had shown that ozone destroys the fast-reacting THM precursors, which are mainly activated aromatic structures and can react with ozone easily; then, the THM formation is slowed. Among the HAAs, trichloroacetic acid (TCAA) can be destructed by ozone easily, while dichloroacetic acid (DCAA) is unaffected. Some compounds, such as halogenated ketones and aldehydes, will form at greater concentrations as a result of prior ozonation. In general, ozone can reduce HAAs, total organic halides (TOX), and THMs to a great extent until the time that the water is consumed. There are many advantages to applying ozone as an alternative to chlorine at the head of the treatment plant. It can delay or even avoid the formation of DBPs from free chlorination. It can also increase the biodegradation, as well as better control tastes and odors, and remove turbidity or filtration effect. Ozone may react with bromide to form hypobromous acid; then, hypobromous can continue to react with NOM to form brominated DBPs:
Lowering the O3 dosage may minimize the formation of BrO3- but increase the formation of other DBPs. On the other hand, higher O3 dosages can lead to significant BrO3formation, particularly at high Br- levels and at ambient pH.
November 2014 • Florida Water Resources Journal
Ozonation converts humic and hydrophobic organic compounds into smaller fragments, but as it does not lead to full mineralization of most compounds, the initial DOC concentration decreases only slightly. Oxidation may produce harmful byproducts and increases assimilable organic carbon (AOC) content, and thus, the potential for bacterial regrowth in the distribution systems. However, these problems can be avoided by combining oxidation with a downstream biological activated carbon (BAC) process prior to the membranes. The granular media filters are widely used prefilters for membrane processes. The media filters capture particles of large-size distribution and, may reduce fouling of the downstream membrane, if employed.
Advanced Oxidation Advanced oxidation processes (AOPs) have been studied intensively for decades. Various combinations of oxidants, radiation, and catalyst have been developed for the removal of TOC, NOM, and organic pollutants; for example, O3/H2O2, UV/H2O2, UV/O3, UV/TiO2, Fe2+/H2O2, Fe2+/H2O2 + hv, vacuum ultraviolet radiation, or ionizing radiation (Fujishima, 1971; Glaze et al, 1987; Legrini et al, 1993; Frimmel, 1994; Nagata et al, 1996; Fukushima et al, 2001; Thomson et al, 2002). These processes involve the generation of highly reactive radical intermediates, especially the OH radical (Glaze et al, 1987). The appeal of AOPs is the possibility to gain complete oxidation or mineralization of organic contaminants through a process that operates near ambient temperature and pressure. Sitnichenko and researchers (2011) reported that greater than 90 percent of fulvic acids could be destroyed using a photocatalytic oxidation by oxygen using UV light and titanium dioxide in surface water over a wide range of pH (3-8).
Summary and Suggested Disinfection Byproduct Water Quality Goals Removal of organic solutes using a variety of unit operation processes is unique to a given water source. However, some generalizations can be made regarding softening: Calcium Carbonate Precipitation - Generally removes from 10 to 30 percent of the color, TOC, and DBP precursors. Has the least capacity for organic removal of solids generally precipitated in precipitative softening. Magnesium Hydroxide Precipitation - Generally removes from 30 to 60 percent of the TOC and DBP precursors, and 50 to 80 percent of the color. Requires primary recar-
bonation to remove excess calcium if lime is used, produces excess magnesium and calcium sludge, and requires either additional sedimentation basins or solids loading on filters if excess calcium is removed. Iron and Aluminum Augmentation - Generally removes an additional 5 to 15 percent of the color, TOC, and DBP precursors in either calcium or magnesium precipitation. Will cause excess sludge formation. Aluminum may be passed through the process and postprecipitate in distribution system. Sequential Treatment - Coagulation following softening will remove additional color, TOC, and DBP precursors; however no additional color, TOC, and DBP precursors will be removed if softening precedes coagulation. GAC - Normally, 80 to 90 percent of the NOM measured in raw water sources can be removed by GAC adsorption. Oxidation - Various combinations of oxidants, radiation, and catalyst have been developed for the removal of TOC, NOM, and organic pollutants.
gested water quality goals for DBPs for communities seeking to establish treatment targets.
References • Adham, S. et al (1991). “Ultrafiltration of Groundwater with Powdered Activated Carbon Pretreatment for Organics Removal.” In proceedings of the AWWA Membrane Technology Conference, Orlando, Fla. • Amy, G.; Alleman, B.C.; and Cluff, C.B. (1990). “Removal of Dissolved Organic Matter by Nanofiltration,” Journal of Environmenal Engineering, vol.116, no.1, pp. 200-205. • Apell, J.N. and T.H. Boyer (2010). Combined ion exchange treatment for removal of dis-
solved organic matter and hardness. Water Research. 44 (8); 2419-2430. • Babi, R.G. et al (2007). Pilot Study of the Removal of THMs, HAA spend DOC from drinking water by GAC adsorption. Desalination. 210, 215-224. • Clark S. G. and Lawler D. F. (1996). “Enhanced Softening: Calcium, Magnesium, and TOC Removal by Geography.” Proceedings of AWWA Water Quality Technology Conference, Nov. 1996. • Comstock, S.E. and Boyer, T.H. (2014). Combined magnetic ion exchange and cation exchange for removal of DOC and hardness. Chemical Engineering Journal. 241, 366-375. Continued on page 52
Table 4. Suggested Water Quality Goals for Disinfection Byproducts
The TOC removal must now be taken into account when evaluating treatment technologies for treatment of surface water supplies. Table 4 provides a recommended listing of sug-
Florida Water Resources Journal • November 2014
51
Continued from page 51 • Drikas, M.; Dixon, M.; and Morran, J. (2011). Long-term case study of MIEX pretreatment in drinking water-understanding NOM removal. Water Research. 45(4), 15391548. • Duranceau, S.J. and Taylor, J.S. “Chapter 11 Membrane Processes.” In Water Quality and Treatment, 6th Edition. Ed., J. K. Edzwald. New York: McGraw-Hill; pages 11-1 to 11106 (2010). • Fabris, R.; Chow, C.W.K.; Drikas, M.; and Eikebrokk, B. (2008). Comparison of NOM character in selected Australian and Norwegian drinking waters. Water Research, 42: 4188–4196. • Frimmel, F.H. (1994). Photochemical aspects related to humic substances. Environ. Int., 20, 373–385. • Fujishima, A. (1971). Electrochem photolysis of water at a semiconductor electrode. Nature, 238, 37–38. • Fukushima, M.; Tatsumi, K.; and Nagao, S. (2001). Degradation characteristics of humic acid during photo-Fenton processes. Environ. Sci. Technol., 35, 3683–3690. • Glaze, W.G.; Kang, J.W.; and Chapin, D.H. (1987). The chemistry of water treatment processes involving ozone, hydrogen peroxide and ultraviolet radiation. Ozone Sci. Eng., 9, 335–352. • Kang, S. and K. Choo (2010). Why Does a Mineral Oxide Adsorbent Control Fouling Better than Powdered Activated Carbon in Hybrid Ultrafiltration Water Treatment? J. Membrane Science. 355: 69-77. • Karanfil, T.; Cheng, W.; Guo, Y.; Dastgheib, S.A.; and Song, H. (2007). DBP Formation Control by Modified Activated Carbons. AWWARF Project 91181. AWWARF, Denver, Colo. • Karpinska, A.M.; Boaventure, R.A.R.; Vilar, V.J.P.; Bilyk, A.; and Molezan, M. Applicability of (MIEX-DOC)-D-A process for organics removal from NOM-laden water. Env. Science and Pollution Research. 20 (6): 3890-3899. • Kim, D.H.; Shon, H.K.; Phuntsho, S.; and Cho, J. (2010). Determination of the apparent charge of natural organic matter. Sep. Sci. Technol., 45: 339–345. • Langlais, B.; Reckow, D.A.; and Brink, D.R. 1991. Ozone in Water Treatment: Application and Engineering. Chelsea, Mich.: Lewis Publishers. • Legrini, O.; Oliveros, E.; and Braun, A.M. (1993). Photochemical processes for water treatment. Chem. Rev., 83, 671–698. • Liao, M. Y. and Randtke, S. J. (1986). “Predicting Removal of Soluble Organic Contaminants by Lime Softteing,” Water
52
Research, Vol. 20, 1, 27-35. • Malley, J.P. Jr.; Edzwald, J.K.; and Ram, N.M. 1986. Preoxidant Adsorption of Organic Halide Formation and Granular Activated Carbon Adsorption of Organic Halide Precursors. In Proc. 1986 AWWA Annual Conference. Denver, Colo.: American Water Works Association. • Mergen, M.R.; Jefferson, B.; and Parsons, S.A. (2008). Magnetic ion-exchange resin treatment: impact of water type and resin use. Water Research. 42 (8-9), 1977-1988. • Metsamuuironen, S. et al (2014). Natural Organic Removal from Drinking Water by Membrane Technology. Separation and Purification Reviews. 43, 1-61. • Nagata, Y.; Hirai, K.; Bandow, H.; and Maeda, Y. (1996). Decomposition of hydrobencoic and humic acids in water by ultrasonic irradiation. Environ. Sci. Technol., 30, 1133–1138. • Oliver, B.G. and Thurman, E.M. 1983. Influence of Aquatic humic substance properties on trihalomethane potential. Water chlorination: Environmental Impact and Health Effects Volume 4, Ann Arbor, Mich.: Ann Arbor Science Publishers Inc. • Owen, D.M.; Chowdhury, Z.K.; Summers, R.S.; Hooper, S.M.; Solarik, G.; and Gray, K. (1998). Removal of DBP Precursors by GAC Adsorption. AWWARF Project 90744. AWWARF, Denver Colorado. • Phetrak, A. et al (2014). Simultaneous removal of dissolved organic matter and bromide from drinking water source by anion exchange resins for controlling disinfection byproducts. J. Env. Sciences China. 26 (6), 1294-1300. • Quinn S. R.; Hashsam, S. A.; and Ansari, N. I. (1992) “TOC Removal by Coagulation and Softening,” Journal of Environmental Engineering, 118 (3), 432-436. • Randtke S. J. et al (1999) “Precursor Removal by Coagulation and Softening,” AWWARF Project 814. AWWARF, Denver ,Colo. • Reiss, C.R.; Taylor, J.S.; and Robert, C. (1999). Surface water treatment using nanofiltration—pilot testing results and design considerations. Desalination, 125: 97– 112. • Roberts, P. V., and Summers, R.S. (1982). Granular Activated Carbon Performance for Organic Carbon Removal. Journal AWWA. 74(2):113-118. • Semmens, M. J. and Staples, A. B. “The Nature of Organics Removal During Treatment of Mississippi River Water.” Journal AWWA, Vol. 78, 2, 76-81, Feb. 1986. • Singer, P.C. (1999). Formation and Control for Disinfection Byproducts in Drinking Water. Denver, Colo.: AWWA.
November 2014 • Florida Water Resources Journal
• Sitnichienko, T.N.; Vakulenko, V.F.; and Goncharuk, V.V. (2011). “Photocatalytic Destruction of Fulvic Acids by Oxygen in a TiO2 Suspension.” Journal of Water Chemistry and Technology. 33(4), 236-247. • Stevenson, F.J. (1994). Humus Chemistry: Genesis, Composition, Reactions. New York: John Wiley & Sons. • Taylor J. S.; Snyder B. R.; Ciliax, B.; Ferraro, C.; Fisher, A.; Muller, P.; and Thompson, D. “Trihalomethane Precursor Removal by the Magnesium Carbonate Process,” EPA/600/S2-84/090, Water Engineering Research Laboratory, Cincinnati, Ohio, Sept. 1984. • Taylor J. S.; Thompson D.; Snyder B. R.; Less J.; and Mulford L. “Cost and Performance Evaluation of In-Plant Trihalomethane Control Techniques,” EPA/600/S2-85/138, Water Engineering Research Laboratory, Cincinnati, Ohio, Jan. 1986. • Taylor, J.S.; Thompson, D.M.; and Carwell, J.K. (1987). Applying Membrane Processes to Groundwater Sources for Trihalomethane Precursor Control. Journal AWWA, 79(8):72. • Taylor, J.S.; Snyder, B.R.; Ciliax, B.; Ferraro, C.; Fisher, A.; Herr, J.; Muller, P.; and Thompson, D. 1984. Project Summary: Trihalomethane Precursor Removal by the Magnesium Carbonate Process. USEPA Research and Development. EPA-600/S2-84090. • Taylor, J.S.; Soyden, S.M.; Lyn, T.L.; and Mulford, L.A. (1992). Investigation and Analysis of Contaminants in the Potable Water Supply of Pinellas County, Final Report on Disinfectant Residual and Byproduct Modelling to Pinellas County, Florida. Environmental Systems Engineering Institute, Civil and Environmental Department, University of Central Florida. • Thompson, J.D.; White, M.C.; Harrington, G.W.; Singer, P.C. (1997). Enhanced Softening: Factors Influencing DBP Precursor Removal. Journal AWWA, 89(6):94-105. • Thomson, J.; Roddick, F.A.; Drikas, M. (2002). Natural organic matter removal by enhanced photo-oxidation using low pressure mercury vapour lamps. Water Sci. Technol.: Water Supply, 2 (5–6), 435–443. • Weiner J.M. (1995). Effects of Ozone on Trihalomethane Formation: Pilot Plant Process and Kinetics. MS thesis. Amherst, Mass.: University of Massachusetts at Amherst. • Yoon, Y.; Amy, G.; Cho, J.; and Her, N. (2005). Effects of retained natural organic matter (NOM) on NOM rejection and membrane flux decline with nanofiltration and ultrafiltration. Desalination, 173: 209– 221.
Florida Water Resources Journal • November 2014
53
FWEA FOCUS
The Meaning—and Worth—of Membership Kart Vaith and Lisa Prieto President and Vice President, FWEA
VAITH
PRIETO
hat is membership to you? What is it worth to you? What do you get out of your FWEA membership? These are questions that we, as your FWEA leaders, have been asking ourselves. We constantly struggle with making sure that our membership is valuable to the FWEA community. We want to make sure FWEA is fun, yet from a professional standpoint, fills a void that many of our members don’t find in
W
54
their day-to-day jobs. For me it would be hard to put a price on my experience at FWEA. My annual dues invoice is an afterthought to me because I feel I am much more than a member, and not just a cog in the wheel of FWEA. We were told by WEF staff in August that dues are being raised $15, effective Jan. 1, 2015, to accommodate the higher costs of providing services. This was no surprise, as the annual inflation rate is about 1.7 percent and this is only the second dues increase over the last decade. Because of the increasing costs, coupled with providing members with more services, including free webinars, discounted conferences, more specialty conferences, and an upgraded interactive website, we weren’t surprised to hear about the increase in dues. Simultaneously, we at FWEA had been debating the same idea. We have recently upgraded our website and have been providing
November 2014 • Florida Water Resources Journal
more elaborate registration and payment services for our events. In addition to the rising costs at FWEA, we recognize that our members are expected to do more with less at work, so they have less time to volunteer for the Association. We have also heard from many of our members that the volunteers are getting burned out and need more help. We have recently done a major overhaul to the website and plan to continue to improve and update it. In addition, we have provided greater registration assistance to our chapters and committees through online registration and credit card processing. By providing more assistance to our FWEA members, we can channel volunteer time to be refocused to the more strategic needs of FWEA. To provide additional help to our overworked volunteers, FWEA has decided to increase dues by $20 annually. Our goal is that, by providing more help and assistance, our volunteers can focus on what is really important to them—whether that be helping to put together the technical program for a seminar, working on the water festival, or writing an article for this magazine. We want volunteer time to be used in the best way possible! And for those of you who haven’t volunteered yet because it seems like a daunting task, there will be more opportunities to volunteer for smaller projects that are less overwhelming. We will also be sending out a membership survey to make sure we are meeting your needs; please look out for it and respond openly and honestly to help us. To reduce the burden on our membership, we are offering FWEA-only membership for our members as well. You can find more information on becoming a member or renewing your dues online at http://www.fwea.org/how_to_join_renew.php. If you have any questions or comments, please don’t hesitate to reach out to us at kvaith@tcgeng.com or lisa.prieto@amec.com, or any of your FWEA leadership team. And as always, thank you for being a member–you are valuable to the FWEA community!
New Products
FWRJ READER PROFILE
The Barracuda Class dredge from DSC Dredge features a swinging-ladder design and is easily transportable, making it ideal for navigational, recreational, or restorative projects such as waterway maintenance and lake revitalization. With the option of two frontswing winches, the dredge can convert from a swing ladder to a conventional one without sacrificing portability. (www.dscdredge.com)
impact on the communities we serve and my company’s success; the chance to work with outstanding professionals throughout our industry; and the opportunity to participate in professional societies that promote the water industry and charitable causes.
The horizontal sludge-dewatering from In The Round Dewatering has a stainless steel drum with perforated plastic tile lining. The drum is mounted on a roll-off frame for easy transportation and unloading. Water trays allow for containment of discharge water. An 18,000- to 25,000-gal batch is mixed with polymer before bring filtered in the rotating drum, driven by a ½ hp variable-speed electric motor with a heavy-duty chain and sprocket. The turning eliminates crusting and wet pockets, producing uniform, consistent results. The dewatering material dumps easily, the drum is self-cleaning, and dewatering can be completed in one night. (www.itrdewatering.com)
The InstoMix high-energy flash mixer from Walker Process Equipment disperses coagulant and other flocculent solutions into raw water and wastewater. The flash blending of coagulant results in optimum floc formation and maximizes chemical company. The compact in-line units are constructed for flange mounting directly in the pipeline and are equipped with an internal-feed manifold designed to distribute solutions uniformly throughout the sectionalized mixer body. The design allows low-energy input, low headloss, and high G-Value results. The agitator can be custom-sized to produce a desired G-Value. Units are available for 8- to 72-in. pipelines. (www.walker-process.com)
Defender Tank Covers from Environetics Inc. are custom manufactured from industrial grade materials to fit the profile of new or existing wastewater treatment tanks or portable water tanks. Odorous gas emissions from wastewater facilities generate complaints from local residents and are subject to the Clean Air Act Amendments of 1990. Defender odor control covers contain volatile organic compounds at the source. Low-profile structurally supported covers minimize emission treatment volume to reduce the cost of air filtration equipment, eliminating the ongoing expense of applying costly odor control chemicals through atomizer and misters. (www.environetisinc.com)
The TLT Series stand-alone primary tank-mounted screen from IPEC Consultants can be used for truck receiving and pumped sanitary wastewater applications. Components include a tank, shaftless screw, screen basket, transport tube, press zone, and discharge section. There are two automatic showers, one inside the tank and one in the press zone and upper transport zone. Influent enters the upstream end of the tank where coarse solids are retained on the surface of the screen basket. The shaftless screw brushes captured solids from the screen surface up the transport section to a press zone, where a plug is formed. Solids are dewatered by compaction against the plug, and liquid is discharged through a short screen section. The press zone shower washes fine, loose solids back into the channel. Compact solids with dryness of 40 percent or more are scraped from the plug and discharged. (www.ipec.com)
What organizations do you belong to? AWWA, WEF, Water For People, and Leadership Florida.
Jeff Nash, P.E. CH2M HILL, Orlando Work title and years of service. I am business development director, American Water Market Public Sector, with 27 years of service in the industry. What does your job entail? I am responsible for business development for the public water sector for the United States, Canada, and Central and South America. The job involves helping communities develop solutions for water supply and water/wastewater treatment and to complete needed projects. I am also responsible for the development of strategic plans for targeting and pursuing new water supply and water and wastewater treatment work, allocating the required resources for these activities, and establishing metrics for meeting firm goals. What education and training have you had? I have a B.S. in chemical engineering and an M.S. in environmental engineering from Virginia Tech. I finished a short course at the Michigan Business School and have taken various sales, financial, and project management courses. What do you like best about your job? There are several things: the opportunity to work on programs and projects throughout the United States and internationally; knowing that my efforts can have a positive
How have the organizations helped your career? They have been an immense help. Every individual in our field should be a member and active participant in a professional organization. It can provide the opportunity to develop relationships with fellow professionals, share technology solutions, and accomplish significant charitable works. What do you like best about the industry? What I like most is that we provide a service of significant importance to society. Clean water and sanitation are two of the most basic human needs. Everyone in our industry should be proud of what they do and the service they provide to their clients and communities. Furthermore, the professionals in our industry are good-hearted people who are great to associate and work with. In addition to their work responsibilities, they are extremely generous with their time and money for charitable causes, including providing educational scholarships and assisting in projects to provide clean water for needy communities around the world. What do you do when you’re not working? When not traveling as part of my job, I stay close to home with my family. We grill or smoke something for friends most weekends. I also grew up working at a golf course and like to play the game. My volunteer time is primarily focused on AWWA activities.
Florida Water Resources Journal • November 2014
55
Certification Boulevard Answer Key From page 20
4. A) Turbidity into and out of the tank Turbidity readings are essential not only in the sedimentation process, but throughout the treatment process from source water to postfiltration. In the sedimentation basin, comparing the turbidity of water entering and leaving the basin will give the operator a good idea of the removal efficiency of the process. Increases in the inlet may indicate changes in source water turbidity or chemical feed problems. In the tank outlet, increased turbidity could indicate a high sludge blanket or a hydraulic overload. Turbidity is one of the essential process control tests for an operator using coagulation.
1. C) Surface contact between the air and water. The efficiency of the aeration process is affected mostly by the amount of surface contact between the air and water. This contact is controlled primarily by the size of the water drop or air bubble. This is why many operators have tried different media to increase turbulence (contact between water and air) in an effort to increase efficiency. The same concept is at play in packed tower aeration units, increasing surface contact between water and air.
5. D) Flash mix
2. A) Increased pH Photosynthesis by algae reduces carbon dioxide in the water; as the carbon dioxide is reduced, the pH will increase. This occurs mainly during the day; at night, respiration by algae will increase the carbon dioxide in the water and lower the pH. Changes in pH levels will impact the treatment process, including coagulation and disinfection.
Flash mixing is the process used to disperse and initially mix coagulant chemicals with water. The entire process occurs in only a few seconds. All the other answers were types of mixers used in the flash mix process.
6. A) 5 to 7 Lower pH levels favor the formation of positively charged particles that will react with the negatively charged nonsettleable particles, causing them to clump together and become heavier and settle out of the water.
3. B) Control water velocity as it enters the basin The other primary purpose of the inlet zone is to start slowing down the water velocity. This is the reason for baffling the tank. Remember, the sedimentation zone is really a settling zone, so the water has to slow down for gravity to work; if not, the formed clumps (floc) of suspended solids will be carried through the tank and onto the filters.
7. B) Galvanic corrosion Galvanic corrosion occurs when one metal gives up electrons to a dissimilar metal. Metals are listed in the galvanic series as to their resistance to give up electrons (corrode). One such metal is gold; it does not easily give up electrons and it does not corrode. Metals
that do not give up electrons are cathodes and those that do give up electrons are anodes. Other metals, such as zinc, easily give up electrons (anodes) and are considered base metals. One way to avoid galvanic corrosion is to install a dielectric fitting (plastic) in between the two dissimilar metals, which will stop the flow of electrons and stop corrosion from occurring.
8. D) They are a stronger disinfectant than chlorine Chloramines are weaker than chlorine, but are more stable. Their stability allows the disinfectant properties to last longer and penetrate biofilm. Chlorine is a stronger disinfectant and very reactive, so over time in the distribution system, all the disinfectant ability may be used up and not be available for use in penetrating biofilm.
9. A) Water hammer Water hammer is caused when fluid in motion—in this case, water—has sudden changes in velocity. The kinetic energy associated with the velocity creates a shock wave of pressure. Increases in pressure related to the sudden stopping of water flow can result in pressure increases of 200 to 400 pounds per sq in. (psi).
10. A) Granular activated carbon Granular activated carbon made from heating carbon, such as wood, has high adsorptive properties that allow it to remove tastes and odors from drinking water. The adsorptive properties of activated carbon do not last indefinitely and the spent carbon must be regenerated or replaced.
PS Form 3526: Statement of Ownership, Management and Circulation (Required by 39 U.S.C. 3685) (1) Publication Title: Florida Water Resources Journal. (2) Publication Number 0896-1794. (3) Filing Date: 09/30/14. (4) Issue Frequency: Monthly. (5) No. of Issues Published Annually: 12. (6) Annual Subscription Price: $6/members, $24/non-members. (7) Complete Mailing Address of Known Office of Publication: 1402 Emerald Lakes Dr., Clermont, FL 34711. Contact Person: Michael Delaney. Telephone: 352-241-6006. (8) Complete Mailing address of Headquarters or General Business Office: 1402 Emerald Lakes Dr., Clermont, FL 34711. (9) Publisher: Florida Water Resources Journal, Inc. 1402 Emerald Lakes Dr., Clermont, FL 34711. Editor: Rick Harmon, 1402 Emerald Lakes Dr., Clermont, FL 34711. Managing Editor: Michael Delaney, 1402 Emerald Lakes Dr., Clermont, FL 34711(10) Owner: Florida Water Resources Journal, Inc. 1402 Emerald Lakes Dr., Clermont, FL 34711. Stockholders: (33 1/3% each) Florida Water and Pollution Control Operators Association, P.O. Box 109602, Palm Beach Gardens, FL 33410-9602; Florida Section/American Water Works Association, 769 Allendale Rd., Key Biscayne, FL 33149; Florida Water Environment Association, 4350 W. Cypress St. #600, Tampa, FL 33607. (11) Known Bondholders, Mortgages, and Other Security Holders Owning or Holding 1 Percent or More of Total Amount of Bonds, Mortgages, or Other Securities: None. (12) The purpose, function, and nonprofit status of this organization and the exempt status of federal income tax purposes: Has not changed during preceding 12 months. (13) Publication Name: Florida Water Resources Journal. (14) Issue Date for Circulation Data Below: October 2014. Average No. Copies Each Issue During Preceding 12 Months
Actual No. Copies of Single Issue Published Nearest to Filing Date
a. Total No. of Copies (Net Press Run)
7,190
7,200
b. Paid and/or Requested Circulation
0
0
7,112
7,121
7,112 0
7,121
(15) Extent and Nature of Circulation
(1) Sales through dealers and carriers, street vendors and counter sales (not mailed) (2) Paid or requested Mail Subscriptions (Include advertisers proof copies/exchange copies) c. Total Paid and/or Requested Circulation (Sum of 15b(1) and 15b(2) d. Free distribution by Mail (Samples, complimentary, and other free) e. Free Distribution Outside the Mail (carriers or other means) f. Total Distribution (Sum of 15c and 15f) g. Copies Not Distributed h. Total (Sum of 15g and 15g) i. Percent Paid and/or Requested Circulation (15c/15gx100)
0
0 0
7,112
7,121
78
79
7,190
7,200
98.92%
98.90%
(16) This Statement of Ownership will be printed in the November 2013 issue of this publication. (17) Signature and Title Editor, Publisher, Business Manager, or Owner. I certify that all information furnished on this form is true and complete: I understand that anyone who furnishes false or misleading information on this form or who omits material or information requested on the form may be subject to criminal sanctions (including fines and imprisonment) and/or civil sanctions (including multiple damages and civil penalties). Date: 9/30/14
56
November 2014 • Florida Water Resources Journal
Florida Team Wins WEF Student Design Competition The team from the University of South Florida was a winner in the 2014 Water Environment Federation (WEF) Student Design Competition, which took place in early October in New Orleans. The team’s project, “South/Central Hillsborough County Service Area Capital Improvements Project,” won in the wastewater design category. A program of WEF’s Students and Young Professionals Committee, the competition promotes real-world design experience for students interested in pursuing an education and/or career in water/wastewater engineering and sciences. The contest tasks individuals or teams of students within a WEF student chapter to prepare designs to help solve a local water quality issue. The projects perform calculations, evaluate alternatives, and recommend the most practical solutions based on experience, economics, and feasibility.
Members of the University of South Florida team were: Lauren Davis, Michael Esteban, Jared Faniel, Andrew Filippi, Win-
some Jackson, Herby Jean, Richard Johnson, and the faculty advisor, Dr. Sarina Ergas.
Florida Water Resources Journal • November 2014
57
ENGINEERING DIRECTORY
Tank Engineering And Management Consultants, Inc.
Engineering • Inspection Aboveground Storage Tank Specialists Mulberry, Florida • Since 1983
863-354-9010 www.tankteam.com
58
November 2014 • Florida Water Resources Journal
ENGINEERING DIRECTORY
Showcase Your Company in the Engineering or Equipment & Services Directory Contact Mike Delaney at 352-241-6006 ads@fwrj.com
EQUIPMENT & SERVICES DIRECTORY
Florida Water Resources Journal • November 2014
59
EQUIPMENT & SERVICES DIRECTORY
Motor & Utility Services, LLC
Instrumentation,Controls Specialists Instrumentation Calibration Troubleshooting and Repair Services On-Site Water Meter Calibrations Preventive Maintenance Contracts Emergency and On Call Services Installation and System Start-up Lift Station Controls Service and Repair
Central Florida Controls,Inc. Florida Certified in water meter testing and repair P.O. Box 6121 • Ocala, FL 34432 Phone: 352-347-6075 • Fax: 352-347-0933
w w w. c e nt r a l f l or i d a c ont rol s . c om
60
November 2014 • Florida Water Resources Journal
CEC Motor & Utility Services, LLC 1751 12th Street East Palmetto, FL. 34221 Phone - 941-845-1030 Fax – 941-845-1049 prademaker@cecmotoru.com • Motor & Pump Services Test Loaded up to 4000HP, 4160-Volts • Premier Distributor for Worldwide Hyundai Motors up to 35,000HP • Specialists in rebuilding motors, pumps, blowers, & drives • UL 508A Panel Shop, engineer/design/build/install/commission • Lift Station Rehabilitation Services, GC License # CGC1520078 • Predictive Maintenance Services, vibration, IR, oil sampling • Authorized Sales & Service for Aurora Vertical Hollow Shaft Motors
EQUIPMENT & SERVICES DIRECTORY
CLASSIFIEDS Positions Av ailable Water Systems Optimization (WSO) is seeking a graduate Civil Engineer with 3 to 5 years of water distribution system experience. The position will require permanent relocation to Nashville, TN. Interested parties can inquire by e-mail to Paul Johnson at paul.johnson@wso.us.
We are currently accepting employment applications for the following positions: Water & Wastewater Licensed Operator’s – positions are available in the following counties: Pasco, Polk, Highlands, Lee, Marathon Maintenance Technicians – positions are available in the following locations: Jacksonville, New Port Richey, Fort Myers, Lake, Marion, Ocala, Pembroke Pines Construction Manager – Hillsborough Customer Service Manager - Pasco
Utilities Storm Water Supervisor $53,039-$74,630/yr. Plans/directs the maintenance, construction, repair/tracking of stormwater infrastructure. AS in Management, Environmental studies, or related req. Min. five years’ exp. in stormwater operations or systems. FWPCOA “A” Cert. pref.
Employment is available for F/T, P/T and Subcontract opportunities Please visit our website at www.uswatercorp.com (Employment application is available in our website) 4939 Cross Bayou Blvd. New Port Richey, FL 34652 Toll Free: 1-866-753-8292 Fax: (727) 848-7701 E-Mail: hr@uswatercorp.com
Asset Management/Project Specialist $50,514-$71,077/yr. Implements and maintains the Utility’s Asset Mgmt & Maint. database. BS degree with major coursework in Computer Science, IT or Communications.
Utilities Treatment Plant Operations Supervisor $53,039 - $74,631/yr. Assists in the admin & technical work in the mgmt, ops, & maint of the treatment plants. Class “A” Water lic. & a class “C” Wastewater lic. req. with 5 yrs supervisory exp.
Utilities Treatment Plant Will Call Operator $17.93-$27.82/hour. Part time. Must have passed the C drinking water or wastewater exam. Apply: 100 W. Atlantic Blvd., Pompano Beach, FL 33060. Open until filled. E/O/E. http://pompanobeachfl.gov for details.
Purchase Private Utilities and Operating Routes Florida Corporation is interested in expanding it’s market in Florida. We would like you and your company to join us. We will buy or partner for your utility or operations business. Call Carl Smith at 727-8359522. E-mail: csmith@uswatercorp.com
Water and Wastewater Utility Operations, Maintenance, Engineering, Management
City of Coconut Creek, FL: Utility Service Worker II (Water) Utilities & Engineering Department Salary: $15.38/hour; $31,990.40 Annually High school diploma or GED; supplemented by up a minimum of two (2) years’ experience in water distribution; an equivalent combination of education, certification, training, and / or experience may be considered. Must have a valid Florida commercial driver's license, Class B or higher; Florida Water Pollution Control Operators Association (FWPCOA) Class “C” Water Distribution certification; and Department of Environmental Protection (DEP) Class III license. ASSE Backflow Certification; Confined Space certification; CPR certification; and intermediate level Maintenance of Traffic (MOT) certifications are preferred, and must be obtained within one (1) year of hire. Apply online at www.coconutcreek.net Florida Water Resources Journal • November 2014
61
City of Vero Beach Electronics Technician
Booth, Ern, Straughan & Hiott, Inc. Utility Design Engineer
Services, maintains, installs and performs preventative maintenance of electronic and electrical equipment throughout the water and sewer system. Must have thorough working knowledge of configuring, programming and maintenance of Modicon Programmable Logic Controllers and GE IFix HMI software version 5.5 and later. Visit website for complete job description, qualifications needed, and instruction to apply. $28.04 p/hr www.covb.org City of Vero Beach EOE/DFWP 772 978-4909
BESH Engineering seeks experienced utility design engineer for all aspects of water and wastewater design, including treatment plants, pump stations, and collection/transmission/distribution systems. Applicant must have water and wastewater treatment plant design and permitting experience. Experience with hydraulic modeling, specification writing, Autocad drafting, project bidding, construction oversight and project funding preferred. Applicant must possess State of Florida E.I. with minimum 4 years experience. Florida P.E. a plus. Salary commensurate with experience. Come join a great team! Drug Free Workplace and an Equal Opportunity Employer. Please email resume to: info@besandh.com
City of Tampa Wastewater Department – Wastewater Operations Manager The City of Tampa is seeking a Wastewater Operations Manager to direct the operation of the municipal wastewater collection and transmission system. Suggested Minimum Requirements: Education: Bachelor’s degree in engineering, public utilities or environmental science Experience: Five (5) years’ experience in wastewater collection/transmission systems with two (2) years’ of manager or supervisor capacity, or equivalent combination of training and experience. License: Valid driver’s license; “A” license in Wastewater Collection within one (1) of employment For more information, please go to the City of Tampa employment website http://www.tampagov.net/employment-services
62
November 2014 • Florida Water Resources Journal
Deputy Director of Utilities Martin County Board of County Commissioners is seeking a Deputy Director of Utilities who will assist in the long range planning for new water supply sources and facilities, provide professional administrative oversight for the County's water & wastewater operations, and coordinate with governmental agencies, engineers and financial staff to assure the most cost effective systems. The ideal candidate will hold a P.E., a bachelor's degree in Civil Engineering and have 8 years of experience in water or public utilities field. Please visit www.martin.fl.us and click on the Jobs board for additional information regarding this position.
KLJ Engineer III - Water System Engineer Are you looking for a stable career with a flexible firm that encourages thinking outside the box? Join a nationally-recognized company that not only survived the last recession, but thrived with exponential growth. KLJ is a multi-disciplinary engineering firm looking for an experienced water system engineer to join our Billings, Montana office location. If you enjoy fishing, camping and skiing in one of the nation’s most coveted environments, look no further. Excellent communication skills, design team experience and a current PE is required. We are an employee-owned company who offers competitive compensation and benefits, 401k, profit sharing retirement program and an environment for personal and professional growth. Apply online today at kljeng.com.
Water and Wastewater Treatment Plant Operators The City of Edgewater is accepting applications for a Water and a Wastewater Treatment Plant Operator, minimum Class C license required. Valid FL driver license required. Annual Salary Range is $31,096 $48,755. Applicants will be required to pass a physical and background check. Applications and information may be obtained from the Personnel Dept or www.cityofedgewater.org, and submitted to City Hall, 104 N Riverside Dr, Edgewater, FL 32l32. EOE/DFWP
Positions Wanted DONALD GAVON – Holds Florida B Wastewater and C Water licenses with 32 years experience and has extensive knowledge in all facets of the water and wastewater industry. Prefers central Florida but will consider other areas. Contact at 4204 Mackerel Dr., Sebring, Fl. 33870. 863-446-1678 MARK McQUAIG – Holds a Florida Double B license with 15 years experience including an excellent electrical background and knowledge of nutrient removals. Prefers the northwest to panhandle area. Contact at 236 Perdue Road, DeFuniak Springs, Fl. 32433. 850-449-9239 KIRK SHAFER – Holds a Florida A Water license with seven years experience and prefers the Naples and adjacent areas but is willing to relocate. Contact at 990 Partridge Circle, Unit #102, Naples, Fl. 34104. 239-435-1940 BILL YOCUM – Holds Florida A Wastewater and B Water licenses. Seeking a position in consulting or contract operation work. Will be retiring in January 2015 and will be available for employment February 1st. Contact at 352-342-2781 or email wyocum5744@yahoo.com
Looking For a Job? The FWPCOA Job Placement Committee Can Help! Contact Joan E. Stokes at 407-293-9465 or fax 407-293-9943 for more information.
– CLASSIFIED ADVERTISING RATES – Classified ads are $18 per line for a 60 character line (including spaces and punctuation), $54 minimum. The price includes publication in both the magazine and our Web site. Short positions wanted ads are run one time for no charge and are subject to editing.ads@fwrj.com
Display Advertiser Index
Editorial Calendar January . . . . . .Wastewater Treatment
American Ductile..................................51
February . . . . .Water Supply; Alternative Sources
CEU Challenge......................................45
March . . . . . . .Energy Efficiency; Environmental Stewardship
Crom....................................................43
April . . . . . . . .Conservation and Reuse; Florida Water Resources Conference
Data Flow ............................................33
May . . . . . . . . .Operations and Utilities Management
FSAWWA Conference ......................15-19
June . . . . . . . .Biosolids Management and Bioenergy Production; FWRC Review
FWPCOA Training ................................41
July . . . . . . . . .Stormwater Management; Emerging Technologies
Garney .................................................5 GML Coating ..................................31, 57 HDR Engineering Inc ......................22-23 Hudson Pump ......................................37 Polston Technology ..............................53 Professional Piping ..............................27 Quality Control ....................................54 Reiss Engineering ..................................7 Severn Trent ........................................62 Stacon ...................................................2 TREEO ................................................32 USA Blue Book ......................................9 US Water ...............................................8 Xylem...................................................64
August . . . . . .Disinfection; Water Quality September . . .Emerging Issues; Water Resources Management October . . . . . .New Facilities, Expansions, and Upgrades November . . . .Water Treatment December . . . .Distribution and Collection Technical articles are usually scheduled several months in advance and are due 60 days before the issue month (for example, January 1 for the March issue). The closing date for display ad and directory card reservations, notices, announcements, upcoming events, and everything else including classified ads, is 30 days before the issue month (for example, September 1 for the October issue). For further information on submittal requirements, guidelines for writers, advertising rates and conditions, and ad dimensions, as well as the most recent notices, announcements, and classified advertisements, go to www.fwrj.com or call 352-241-6006. Florida Water Resources Journal • November 2014
63