Environmental Science & Engineering Magazine | June 2021 by Environmental Science and Engineering Magazine

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Repairing and protecting a 1950s era wastewater digester tank

Strategies to increase existing reverse osmosis unit output

Treatment options for PFAS contaminated groundwater Kelowna deploys high-tech sewer monitoring system

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CONTENTS

June 2021 • Vol. 34 No. 3 • ISSN-0835-605X

Editor and Publisher STEVE DAVEY steve@esemag.com Managing Editor PETER DAVEY peter@esemag.com Sales Director PENNY DAVEY penny@esemag.com ales Representative DENISE SIMPSON S denise@esemag.com Accounting SANDRA DAVEY sandra@esemag.com Design & Production MIGUEL AGAWIN miguel@esemag.com Circulation BRIAN GILLETT ese@mysubscription.ca

TECHNICAL ADVISORY BOARD

Archis Ambulkar OCT Water Quality Academy Gary Burrows City of London Patrick Coleman Stantec Bill De Angelis Metrolinx Mohammed Elenany Urban Systems William Fernandes City of Toronto Marie Meunier John Meunier Inc., Québec Tony Petrucci TMIG The Municipal Infrastructure Group Environmental Science & Engineering is a bi‑monthly business publication of Environmental Science & Engineering Publications Inc. An all Canadian publication, ES&E provides authoritative editorial coverage of Canada’s municipal and industrial environmental control systems and drinking water treatment and distribution. Readers include consulting engineers, industrial plant managers and engineers, key municipal, provincial and federal environmental officials, water and wastewater plant operators and contractors. Information contained in ES&E has been compiled from sources believed to be correct. ES&E cannot be responsible for the accuracy of articles or other editorial matter. Articles in this magazine are intended to provide information rather than give legal or other professional advice. Canadian Publications Mail Sales Second Class Mail Product Agreement No. 40065446 Registration No. 7750

25 FEATURES 6 10 12 14 16 19 20 22 25 26 28 31 32 36 38 41 46 49 50 51 52

Hamilton’s “Sewergate” shows there will be future wastewater spills Kelowna deploys high-tech sewer monitoring system Feds introduce new ammonia discharge regulation for metal and diamond mines Technology can improve water supply, reduce energy use and increase sustainability Norfolk County commissions condition assessments on its water transmission network Saskatchewan city completes third phase of drinking water upgrade Bridge prevention is key to successful sewage sludge handling applications Advantages of using peristaltic dosing pumps for fluids with particulates or chemicals that off-gas Constructing a new child care facility directly above its stormwater system Determining when it is time to replace reverse osmosis membranes Treatment options for PFAS contaminated groundwater Collingwood halts construction as it discovers water demand outpacing capacity Strategies to increase existing reverse osmosis unit output Measurement methods for chemical storage tank inventory calculation Creating a safe chemical storage system Repairing and protecting a 1950s era wastewater digester tank Monitoring small watersheds is vital to community safety and water sustainability Edmonton engineering firm piloting a novel machine learning water treatment process Scraper strainers resist clogging and fouling when faced with micron-sized particles Monitoring solvent emissions to ensure compliance Novel aeration system can improve the performance of wastewater treatment lagoons Dealing with the challenges of cleaning municipal sewer and stormwater lines A simple approach to improve the quality of rice paddy processing wastewater

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Environmental Science and Engineering Magazine

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GUEST COMMENT

Hamilton’s ‘Sewergate’ shows there will be future wastewater spills By John Smythe

ts difficult to be part of the environmental industry and not be disheartened when you hear about things like Hamilton’s “Sewergate”. For those not familiar with the details of this event, it involved a 24 billion litre spill of diluted raw sewage from a combined sewer overflow (CSO) tank that occurred over a four-and-a-half-year period (2014-2018), which caused damage to Cootes Paradise in Hamilton, Ontario. This is enough discharge to fill 10,000 Olympic sized swimming pools, only these pools would be full of human feces, syringes, condoms and tampon inserters. Cootes Paradise is the name of the river mouth wetland that represents the western terminus of Lake Ontario and is named after Thomas Coote, a British Army officer stationed in the Niagara area during the American Revolutionary War. The wetland site carries multiple designations, including a National Historic Site, a Nationally Important Bird Area (IBA), and an Important Amphibian and Reptile Area (IMPARA), and it is home to dozens of species of native plants, mammals and amphibians. Sewergate does not represent the first time Cootes Paradise has been assaulted with copious quantities of raw, untreated sewage, but it is the worst example. Over the years, there have been hundreds of similar smaller discharges to this exact same area. Why? Because the CSO tank was designed that way. So, if it was designed that way, doesn’t it make sense that it could also be re-designed to prevent such events in the future? The simple answer is, of course, yes. Hamilton is home to one of the oldest and most complex level IV sewage collection systems anywhere and is situated in the centre of a highly eco-sensitive area. It could be the model of how a highly industrialized city handles their sew6 | June 2021

Princess Point, Cootes Paradise in Hamilton, Ontario.

age, but environmental horror stories just keep occurring in the area year after year, decade after decade. The main issue that distinguishes Sewergate from flawed design features, such as intended overflows, is that it was caused intentionally. Preliminary information has revealed that the sewage gate at the King Street CSO tank was manually opened on January 28, 2014, which began the four-anda-half-year long spill. Yet, it seems that no one at the City of Hamilton knows who ordered the gate opened and no one seems to know who actually turned the valve. It’s odd that the exact date can be identified but nothing else. Combined sewer overflows typically take place during heavy rainfall events, or heavy snow melt events, when single pipe systems are overwhelmed with volume. However, weather records indicate that the temperature on January 28 was a high of -140C, the low was -230C.

Hardly “melt” weather. In fact, the last time the temperature had been above zero was eleven days earlier on January 17, when it reached +10C, again, hardly heavy melt weather. There had been no rainfall in weeks, so if the decision to open this valve was not determined by weather conditions, it would stand to reason that it was done for operational purposes. Early information indicates that even though the gate was opened manually, computer systems recorded “normal” conditions. Clearly things were not normal. It is common knowledge in the industry that mechanical and communication failures can often be traced back to poor maintenance and inspection of critical components such as gate positioning detectors or flow indicators. However, four and a half years is a long time for something to go undetected. Diligence with regard to monitoring, inspections and log book entries continued overleaf…

Environmental Science & Engineering Magazine

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GUEST COMMENT is among the rudimentary first principles you learn as an operator. The current CSO design only allows disasters such as this to continue to happen. I wasn’t part of the decision making, but I was there to hear the conversations when the CSO tanks were being conceived. The two ideologies being considered at the time were complete sewer separation or the installation of CSO tanks. After much debate, a decision had to be made and the CSO tanks were considered the most effective and least disruptive solution. For the most part, the CSO tanks have served their purpose well. But, any system that is affected by several changes in provincial and municipal governments, numerous budget cutbacks, staff changes and the rapidly increasing severity of precipitation events due to climate change, was just another accident waiting to happen. Investigations like this take time and they cost a lot of money which can slow

the progress needed to actually rectify the problem. By the time a conviction or an acquittal is handed down it will no longer be front page news. Surely the millions of dollars spent on prosecution and defence proceedings would be better spent on repair and remediation of the damaged wetlands. According to a senior spokesman from the Royal Botanical Gardens, 10 year's worth of environmental progress at Cootes Paradise has been wiped out by Sewergate. They added that it will be years before conditions can begin to return back to what they were prior to the spill. We continue to push the environmental envelope further and further down the road of destruction despite decades of warnings from experts around the world. Until this caustic global mindset changes, there will always be another Sewergate somewhere. That is really quite sad, considering it’s all very preventable. If the solution to this catastrophic

event is not properly thought through this time, rather than talking about the Cootes Paradise recovery we could very well be talking about Paradise Lost. John Smythe worked for a number of years at the Region of HamiltonWentworth Environmental Department. He has authored a number of articles on issues facing the wastewater sector. Email: contact@nova-td.net

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WASTEWATER

Kelowna deploys high-tech sewer monitoring system

radled within a glorious range of mountains, Kelowna, British Columbia, is a sanctuary filled with pristine lakes, pine forests, abundant gardens, orchards and vineyards, sandy beaches and other amenities. Stretching from north to south for approximately 135 km is beautiful Okanagan Lake. It sustains several diverse communities, with long, warm summers and short, mild winters. The City of Kelowna is the largest community and is located midway through the valley. It has a rapidly growing population and is the primary transportation, business and service hub of the valley. Kelowna’s wastewater system collects, conveys, treats and disposes of domestic and industrial wastewater from homes and businesses. On a peak day, wastewater treatment exceeds 42 million litres. Wastewater is conveyed to Kelowna’s wastewater treatment facility (WWTF) through a network of 595 km of sewers and 49 lift stations. All of the wastewater operations need to be managed as efficiently as possible with relatively limited staff resources. At the same time, operations need to accommodate a rapidly growing population and address new challenges, such

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as monitoring hydrogen sulfide (H₂S), creek levels, and optimizing cleaning efficiency. Kelowna has become a leader in the use of SmartCover technology across a variety of innovative applications. Primary among these is the deployment of H₂S monitoring sensors to more accurately manage H₂S levels. The distinctive, persistent rotten egg smell created by the presence of H₂S is a nuisance to employees, residents and businesses located near manholes and treatment facilities. H₂S also causes corrosion to pipes, leading to shorter asset life and increased replacement costs. Kelowna now has remote, real-time visibility into their sewer system using SmartCover’s instant infrastructure. Real-time H₂S monitoring has resulted in significant cost savings, allowing staff to combine remote H₂S level data with remote dosing to minimize staff trips to the field. The city is also leveraging many SmartCover features. These include the off-grid aspect of satellite communications, to address a wide range of innovative and preventative wastewater applications, such as overflow prevention, optimization of high-frequency cleaning, and ongoing inflow and infiltration (I&I) studies.

In addition, other departments in the city were able to take advantage of SmartCover technology for monitoring H₂S in leachate from a solid waste facility, and stream level monitoring. An added benefit for all city users has been the ability to access the same cloud-based system user dashboard to view reports that have analytics across applications. There is also the ability to retain archived data from previously-deployed sites, in order to easily view comparisons with historical data for performance evaluation. For more information, visit: www.smartcoversystems.com

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WASTEWATER

Feds introduce new ammonia discharge regulation for metal and diamond mines By Kareena Gill

ining is a foundational industry and contributes billions to the economy through taxes and spending. The sector is subject to strict environmental regulations and is gaining global recognition for ethical mining. On June 1, 2021, amendments to the Metal Mining Effluent Regulations (MMER) under the title of Metal and Diamond Mining Effluent Regulations (MDMER) came into force. Of particular significance is the ammonia discharge limit. Several activities in a mining operation introduce ammonia to its wastewaters. Two major sources are the cyanidation of gold ore and the use of ammonium nitrate-based explosives. Degradation of cyanide and the ammonium and nitrate in the explosive residue results in the release of ammonia. If it is discharged to the environment, untreated ammonia in mine-contacted water is harmful to aquatic life. The presence of ammonia in fish habitats has proven to be highly toxic. Fish do not possess the ability to eliminate ammonia from their body and therefore accumulate it even at low concentrations in water. Salmonids, especially trout, are extremely sensitive to ammonia. The low toxicity threshold for un-ionized ammonia for rainbow trout has been established to be 0.4 mg-N/L by the Canadian Council of Ministers of the Environment. To limit the risks of the negative effects of mines on fish and fish habitat, the latest criteria under MDMER impose a limit on ammonia release for end-of-pipe discharges. The discharge of un-ionized ammonia from mines will now be required to comply with a monthly mean concentration limit of 0.5 mg-N/L. This regulation will apply to new, existing, and re-opening mines from June 2021. To treat elevated ammonia levels in 12 | June 2021

A mining operation near Sechelt Inlet, B.C. Credit: edb3_16 / AdobeStock

mine-contacted water before discharge, existing mine water treatment systems will have to be upgraded and/or new systems designed per the new criteria for ammonia discharge. A brief overview of ammonia removal technologies follows: Biological treatment – With the help of different types of bacteria, ammonia is oxidized to nitrate (nitrification) in an aerobic process and then the nitrate is reduced to nitrogen gas (denitrification) under anoxic conditions. Oxidation – Oxidizing reagents such as chlorine, hydrogen peroxide and ozone are used to oxidize ammonia to nitrogen gas, or an electrochemical system is used to produce the oxidizing reagent. Adsorption – Total ammonia in the form of ammonium and ammonia-metal complexes is removed by adsorption through the use of zeolites or ion exchange resins. Membrane separation – Technologies like reverse osmosis (RO) and nanofiltration (NF) are available for ammonia removal from the mine effluents.

Air stripping – Various systems available include conventional packed towers and aerators with the ability to be installed in storage ponds. Ammonia is removed from mine-impacted water by mass transfer from water to air. This new ammonia regulation is expected to affect over 100 metal and diamond mines across Canada. The best treatment approach should be selected based on a site-specific comprehensive assessment of the mine data and a thorough feasibility study. Kareena Gill is with McCue Engineering Contractors. Email: kareena@mccuecontracting.com

Environmental Science & Engineering Magazine

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WASTEWATER

water, wastewater tech can improve supply, reduce energy use, increase sustainability By Cameron Creech

he water and wastewater sectors are increasingly embracing new technologies to improve supplies, reduce energy use and increase environmental sustainability. For example, the potential of water resources recovery facilities to generate energy via anaerobic digestion (AD) is well understood, but in many cases, AD is used primarily for wastewater treatment rather than energy generation. Utilizing the biogas produced for heat, power, or as renewable green gas will immediately bring both economic and environmental benefits. Where thermal processing is used, heat recovery enables a resource that would otherwise go to waste to be used for purposes such as pre-heating items, including process water, feedstock, digesters or evaporators to improve energy efficiency. Heat exchangers are a good way to recapture heat from thermal processes, as a well-designed system can recover and reuse 40% of the heat produced by a wastewater AD plant. One type proving popular with wastewater AD operators is The trend for wastewater treatment plants to add biomethane the HRS DTI Series of double tube heat exchangers. upgrading technology is increasing. The inner tube is corrugated to ensure improved heat transfer performance and resistance against fouling, which also results in reduced maintenance periods. In addition, the tube in tube design permits the processing of fluids with particles without any tube blockage, making it particularly suited to wastewater, sewage and AD plants. IMPROVING THE VALUE OF BIOSOLIDS AND DIGESTATE A typical five million BTU wastewater AD plant can produce around 40,000 tonnes of liquid digestate each year, which creates significant economic and logistical challenges in terms of management, storage and transportation. Generally, concentrated digestate and sludge is easier to manage. Using surplus or recovered heat to separate water from digestate by concentration can reduce the overall quantity of digestate by as much as 80%, greatly lowering the associated storage and transport costs. HRS’ digestate concentration system (DCS) includes measures to retain the valuable nutrients in the digestate, while the evaporated water can be condensed and returned to the front end of the AD process. This reduces the amount of energy and water used by the plant. After concentration, the treated digestate dry solid content can be as high as 20% (often a four-fold improvement), making it much easier, and cheaper, to transport and handle. Pasteurizing digestate and sludge to remove potential pathogens is a tried and tested technique around the world, allowing these valuable biofertilizers to be utilized on a wide range of soils and farming systems. HRS’s digestate pasteuriza14 | June 2021

HRS’s digestate concentration system installed at a biogas plant.

tion system (DPS) uses heat exchangers rather than tanks with heating jackets. Using heat exchangers means that effective digestate pasteurization is possible using surplus heat, while allowing additional thermal regeneration levels of up to 60%. This saved heat can then be used for other processes, such as evaporation of the digestate to remove water. EFFICIENT EVAPORATION Evaporation and cooling processes are commonplace in Environmental Science & Engineering Magazine

water and wastewater treatment, but evaporation can result in a high degree of material fouling on the inside of the equipment. HRS Unicus Series scraped-surface heat exchangers are designed to maintain thermal efficiency and remove fouling as it occurs. Low temperature evaporation can be a very energy efficient method of water removal. Where process temperatures are 85°C to 90°C, low temperature evaporation combines the use of a vacuum to reduce the boiling point of the liquid to be removed, together with traditional high temperature evaporators, based on heat exchanger technology. Where the temperature of the effluent or digestate falls below the necessary temperature, it can often be increased via heat exchangers, utilizing surplus heat from heaters and combined heat and power engines. Combining systems into a multiple-effect evaporator allows larger quantities of water to be removed for the same initial heat input. Each evaporator

is held at a lower pressure than the previous one. This is because the boiling temperature of water decreases as pressure decreases. The vapour boiled off in one vessel can be used to heat the next, so only the first vessel requires an external source of heat. This can be taken from another process elsewhere, or generated specifically for the purpose.

Coupled with HRS R Series coolers and custom-designed crystallization tanks, the result is an efficient process that can work continuously without requiring scheduled downtime. Two evaporators are used to concentrate and remove pure water from the solution, which can be used elsewhere. The coolers and crystallizers produce solid crystals, and the remaining soluRESOURCE RECOVERY tion returns to the evaporation process. One common use of evaporation is The system can be configured as a true in material recovery and waste valoriza- zero liquid discharge system, so no liqtion, or the process of recovering value uid waste remains after the process. This from waste materials. Solid-liquid mix- means that by recovering valuable mintures are complex, and it is important erals and salts, waste management costs that the first stage of resource recovery are also reduced. accurately evaluates the nature of the waste stream(s) involved. Cameron Creech is with HRS Heat The evaporation and cooling steps that Exchangers. For more information, are often involved in resource recovery email: info@us.hrs-he.com, or visit: result in a high degree of material fouling www.hrs-heatexchangers.com on the inside of the equipment. HRS Unicus Series scraped-surface heat exchangers are used to maintain thermal efficiency and remove fouling as it occurs.

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WATER

Norfolk County commissions condition assessments on its transmission network By Alain Lalonde

N A sensor is connected magnetically to the valve and by cable to the transmitter.

orfolk County, a municipality in Ontario, has a population of more than 60,000 residents. It recently encountered a main break on its 300-mm ductile iron transmission watermain. As this is the only feed from the community of Port Rowan to the community of St. Williams, the impact to residents was significant. Operations staff suspected that the leak on this line was caused by pitting corrosion, a common cause of failure in ductile iron pipes. During the repair, they noted that there was significant deterioration and corrosion on the bottom section of the watermain.

“Norfolk County has other communities that are fed from well sites via these transmission mains. These sites are also vulnerable because of the single feed and lack of redundancy,” said Jeff Demeulemeester, project manager for Norfolk County. Norfolk’s 10-year capital plan is an integral component of its long-term financial sustainability program and underscores the importance of ensuring projects are prioritized, substantiated and affordable. It was therefore imperative to understand the existing condition of its watermains to ensure effective preventative maintenance.

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The county put out a request for proposal for condition assessment of its watermains. After rounds of trials and deliberation, Echologics ePulse non-invasive condition assessment technology by Mueller was selected to determine the existing structural condition and locate any existing leaks and anomalies. For this project, Echologics tested approximately 6.9 km of the ductile iron transmission main running primarily along Front Road. Norfolk selected this section of pipe due to its lack of redundancy and previous break history. Since a failure on this line could also have a large impact on Norfolk’s residents, a condition assessment survey was performed to determine if any areas along the line had experienced significant degradation. Based on the findings, engineering firm AECOM would recommend pipeline renewal options, if needed. ePulse technology was implemented by attaching two acoustic sensors, each to an existing contact point, such as a fire hydrant, valve or directly in contact with the pipe wall. A soundwave was induced in the pipeline and its propagation speed was measured between the two acoustic sensors. The speed at which the soundwave traveled was dictated by the condition of the pipe wall. After field work was completed, the speed of sound was combined with other information collected on site, including distance and water temperature, and then, using proprietary advanced algorithms, the technology determined the average wall thickness remaining for each segment. These results were interpreted in the form of three categories: “good”, “moderate” and “poor”. A wall loss percentage that was less than 10%, was denoted as good; a wall loss percentage from 10% to 30% was denoted as moderate; a percentage that was larger than 30% was classified as “poor”. “Each ePulse result represented an average condition within a segment between two sensor attachment points. Often, when planning a replacement program, asset managers are looking for an overall score representative of pipe condition to rank pipe for replacement. ePulse results are great for this purpose” said Khalid

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Kaddoura, project manager for AECOM. The second part of the project required an investigation for leaks and anomalies, which was simultaneously fulfilled during the condition assessment. This is the advantage of deploying ePulse as both assessment and leak detection as they could be performed at the same time with the same acoustic correlator.

After a 12-day assessment period, ePulse results indicated that 12 of the 54 segments were in poor condition with an average wall thickness loss greater than 30%. Thirty segments appeared to be in moderate condition with 10% to 30% loss in original wall thickness. Eleven segments appeared to be in good condition with less than a 10% loss continued overleaf…

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June 2021 | 17

WATER lic performance was recommended to A secondary investigation later confirmed that the be assessed. If it fell within the acceptable range, additional assessment would leak noise originated from a normal functioning be performed to check the water characteristics. pressure reducing valve within a meter pit. A rehabilitation intervention was recommended if water quality did not comply with the local standards. in original wall thickness. The remain- minor as it provided Norfolk County On the other hand, if the watermain’s ing one segment could not be assigned with the required data to prioritize the hydraulic performance was unacceptable a result. replacement of our transmission main and/or was determined to be in the poor No leaks were detected during the time network over the 10-year capital plan. condition category, a replacement was of the survey. However, a point of inter“Based on a ‘worst first’ replacement recommended should larger hydraulic est (POI) was identified. POI designation schedule, we were able to align the tim- capacity be required. indicated that some, but not all of the cri- ing with our required financial planning,” If the hydraulic capacity was sufficient, teria for a positive leak detection result said Demeulemeester. renewal techniques were considered on were met. Based on the results collected by the a case-by-case basis, depending on cost A secondary investigation later con- Echologics field team, AECOM devel- and construction footprint analysis. firmed that the leak noise originated from oped a customized renewal decision tree, Following the project completion, a normal functioning pressure reducing along with budgetary cost estimates of Norfolk County scheduled the replacevalve within a meter pit. some renewal options. ment of pipe sections with poor condi“We are pleased that the project proIncorporating ePulse inspection results, tion, with more sections identified to be vided the data we required to priori- the decision tree was based on the three replaced in its 10-year capital plan. tize and make an educated schedule for condition categories: good, moderate, replacement based on the watermain’s and poor. Alain Lalonde, P.Eng., is with remaining wall thickness. Furthermore, For the first two categories of good Echologics/Mueller Canada. Email: the cost of the assessment was considered and moderate, the watermain’s hydrau- alalonde@echologics.com

Customized decision tree to select renewal methods (rehabilitation vs. replacement) for the 54 pipe segments based on the ePulse® inspection results. 18 | June 2021

Environmental Science & Engineering Magazine

WATER

Saskatchewan city completes third phase of drinking water upgrade

askatchewan residents in the City of Estevan can expect “noticeably improved, less hard” drinking water, municipal officials explained, as they unveiled the third and final phase of the community’s drinking water system upgrade project. As a result of the upgrades, the city of 14,000 that sits near the U.S.-Canada border will soon shift its primary water source from the Boundary Dam to the Rafferty Dam. “This project has been several years in the making and we are happy to be able to announce that residents will have a cleaner water source with fewer trihalomethanes,” announced Estevan Mayor Roy Ludwig. The first of three phases for the drinking water upgrades began in 2017 with the construction of two settling ponds to protect the Souris River by storing residuals generated by the water treatment plant. The ponds alternate collecting the residuals as part of the water treatment process. Phases two and three of the drinking water upgrades were completed in tandem. These included construction of a 9.2 kilometre-long water pipeline that runs from the original riverbed in the Rafferty Dam Reservoir to the Estevan Water Treatment Plant. The third and final phase of the project was the intake line from the dam and the construction of a pump house that will soon be commissioned. KGS Group was a primary consultant on the upgrades. The City of Estevan Water Treatment Plant was established in the 1950s. The average consumption of water is close to 5,000 cubic metres per day, with a peak daily use of 10,000 cubic metres. Through the Provincial-Territorial Infrastructure Component – National www.esemag.com @ESEMAG

Estevan’s drinking water tower. Credit: Wtshymanski, Wikimedia Commons

and Regional Projects program, the governments of Canada and Saskatchewan are each contributing up to $3.1 million toward the Estevan Water Treatment System Upgrades Project. The City of Estevan is responsible for any remaining costs of the project, which has a total eligi-

ble cost of $9.4 million under the program. Earlier, in 2004, several other upgrades were completed to improve the quality and the disinfection of the drinking water for the city. These included new filtration, chemical feed systems, and the addition of ultraviolet disinfection reactors.

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June 2021 | 19

BIOSOLIDS MANAGEMENT

Bridge prevention is key to successful sewage sludge handling applications By Jason Balcerczyk

olids content of sludge cake in sewage sludge handling operations is a persistent problem. High-solids sludge leads to bridging, which in turn can lead to significant process downtime and pump maintenance demands. Traditional bridge-breaking technology fails to adequately address bridging in the resulting difficult-to-convey sludge applications. More recently, improved technology, such as NETZSCH Pumps & Systems’ aBP-Module , has proven to be highly effective in ensuring bridge prevention. This leads to continuous plant uptime and minimal pump system repairs.

BRIDGING CAUSES DOWNTIME, HARMS EQUIPMENT IN SLUDGE HANDLING Bridging, a stubborn issue in sewage sludge handling applications, occurs when thick and dry dewatered sludge cakes together. Once the sludge sticks together, bridges between the side walls form as sludge falls into the hopper of a pump and starts to stick to the side walls above the pump auger.

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The aBP-Module®’s spoked wheels prevent sludge buildup, while conveying any bridges that form directly to the auger to be broken up.

These bridges can prevent additional sludge from falling into the pump by blocking off the opening, thereby ceasing pump operation. As the sludge piles up on top of the bridge, it backs up the process until eventually it overflows out of the hopper, or triggers an alarm. At this point, the portion of the plant in question must shut down until a

maintenance crew can address the situation. This involves breaking down the bridge over the pump auger, cleaning up any overflowed sludge, resetting alarms, and pumping the overflow sludge manually until the sludge feed is back within normal operating parameters. Depending on the plant setup and failure modes, the delay to plant operation can last any-

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Environmental Science & Engineering Magazine

where between an hour to a whole day. An even more troubling issue caused by sludge bridging occurs if the pump continues to run without any sludge feeding into it. If the pump runs dry in this manner, the stator will heat up and, if the pump is not switched off in time, it can be destroyed. Stator damage causes the entire pump to fail, requiring repairs and extensive plant downtime. Typically, plants have safeguards in place in order to avoid dry running and the resultant pump damage, although occasionally these safeguards are not sufficient and damage occurs anyway. Even when dry running is prevented, bridging problems likely impact plant schedule and require reassignment of staff and equipment, delivery/pick up schedules, or adjustments to other portions of the plant process.

and specialized cake pumps in order to properly and efficiently handle thicker sludges.

BENEFITS OF IMPROVED ANTI‑BRIDGING TECHNOLOGY The aBP-Module® works by creating the effect of a moving wall with the use of spoked wheels. By having the wheels rotate into the auger feed zone, bridges do not have enough time to form. If they do form, they are carried along to the auger by the wheels, thus breaking the bridge as it engages the auger. The spoked wheels continually change the wall dynamics and keep it free from bridging. Moreover, they are very close to the sides so as not to interfere with the sludge flow into the pump. The aBP-Module is typically used for sludges with solids content ranging from roughly 25% – 40%. TRADITIONAL BRIDGE‑BREAKING Given that the wheels are to the sides TECHNOLOGY and not in the product flow path, there With the growing need to remove is no buildup of sludge, hair, rags, or more water from sludge cake, the per- other materials. The paddle wheels of centage of solids in sludge cake is increasingly higher. This causes the sludge to be stickier and harder to convey, and therefore exacerbates bridging. As a result of the serious issues caused by sludge bridging and the increase in its frequency and severity, a number of pump companies incorporate bridge-breaking technology into their pump systems designed for sludge handling. The traditional type of bridge-breaking technology is single or dual paddle wheels resting above the auger of the pump. This technology has two areas where bridging can still form: above the paddles and between the paddles and the auger. Also, given that the paddles are in the direct flow path of the sludge, they can collect a buildup of hair, rags, or other materials that can get wrapped around the shafts. Another very common anti-bridging technology present in pump systems is vibrators. These devices vibrate the walls and the sludge media in order to prevent sludge buildup. However, vibrators decrease in efficacy as solids percentage and sludge stickiness increases. With highly sticky sludge, pump systems require improved sludge handling equipment in order to prevent bridging, www.esemag.com @ESEMAG

the traditional technology require four times more power to operate per paddle than the aBP-Module. Finally, it requires zero maintenance due to buildup or bridging, with the resulting lesser chance of the pump running dry during a blockage than traditionally-designed systems. The aBP-Module, therefore, does not lead to process downtime due to either pump shutdowns or maintenance. The aBP-Module technology is compatible with all of NETZSCH’s open hopper pump models and can be adapted to hoppers of all sizes. For very large hoppers, the wheels can be doubled or tripled as needed. Jason Balcerczyk is with NETZSCH Canada, Inc. For more information, email: jason.balcerczyk@netzsch.com, or visit: www.netzsch.com

June 2021 | 21

PUMPS

advantages of using peristaltic dosing pumps for fluids with particulates or chemicals that off-gas By Jean Hendrickson

peristaltic metering pump is a type of positive displacement pump. Fluid is pumped through a flexible tube in a peristaltic motion. Rollers are attached to a rotor which is controlled by a motor. As the rotor turns, these rollers pinch the tubing to force fluid through. When the tube is not compressed, the fluid flow is brought into the tube. Peristaltic metering pumps excel at pumping dirty fluids that contain particulate matter into lower pressure systems, because they have no check valves to clog. The gentle forces created during the peristaltic pumping action will not damage delicate fluids within the tube. Peristaltic pumps are also extremely effective when pumping fluids that contain trapped gases. Fluids, such as chlorine and hydrogen peroxide, tend to release absorbed or occluded gases when subjected to a vacuum or changes in temperatures. Peristaltic pumps are capable of pumping both fluids with particulates and those that off-gas, without loss of prime or vapour lock. Peristaltic pumps easily prime under maximum pressure, but are usually limited to maximum discharge pressures of around 125 psi. In addition, they are capable of injecting into a vacuum without the need for metal spring-loaded valves. Their output volume does not change due to changes in the system pressure. Diaphragm pumps can operate at higher system pressures, but require the addition of metal spring-loaded valves to resist siphoning. They are also more difficult to prime against pressure and their output will vary with system pressure changes.

22 | June 2021

As the pump’s rotor turns, rollers pinch the tubing to force fluid through. When the tube is not compressed, the fluid flow is brought into the tube.

membrane bioreactor filter backwashes, a third pump injects 93% sulfuric acid prior to reverse osmosis. An additional pump injects 12% – 14% sodium hydroxide to bring reclaimed water to a pH of 8 to prevent pipe corrosion. The Blue-White FLEXFLO® peristaltic dosing pumps they chose allowed gas accumulation to be pumped through the tubing, while also maintaining a smooth, accurate, and constant rate of flow, with no potential for vapour lock.

PERISTALTIC PUMPS AT AN ENERGY COMPANY TO TREAT REUSE WATER An energy company needed pumps to inject 12.5% sodium hypochlorite into reuse water to prevent biological buildup within the water tubes of their condenser. Any buildup within the condenser would greatly reduce efficiency to produce steam, hence less mechanical power. The company chose a Blue-White CHEM-FEED duplex skid system with two of the company’s FLEXFLO peristaltic chemical dosing pumps. The perA Blue-White CHEM-FEED duplex skid system istaltic pumps maintained their flow selected for sodium hypochlorite dosing by an without losing prime. energy company. When they are in use, the pump operator must be aware that constant squeezing of the tube degrades it over time, PERISTALTIC PUMPS IN A BREWERY slowly diminishing the feed rate. WASTEWATER TREATMENT SYSTEM Most manufacturers rate tubes in One popular brewing company has hours and the user must keep track of been using peristaltic pumps to assist how many hours the pump has been with the purification of wastewater gen- running. When pump tubes are not regerated by its craft brewery. The brewery ularly changed, or the injection point is and the packaging hall generate about not serviced, the pump tube may begin 380,000 litres of wastewater per day. A to leak. pump was needed that would not vapour Blue-White’s exclusive, patented Flexlock due to the aggressive off-gassing A-Prene® multi-tube technology saves chemicals being dosed. maintenance time and expense. These The facility uses two peristaltic pumps innovative pump head tubes provide to inject 12.5% sodium hypochlorite into continued overleaf… Environmental Science & Engineering Magazine

Your Pipelines Are Speaking.

Are You Listening? Water infrastructure renewal and replacement is an ongoing task. Stemmed from vast experience and validated results, Echologics® ePulse® Pipe Condition Assessment technology can help utilities determine the condition of aging pipelines. Trusted by utilities globally, this non-invasive solution identifies segments most likely to fail first, while simultaneously pinpointing leaks. With limited capital budgets for pipeline renewal programs, ePulse® delivers pipeline data worth listening to. Call us today at 866-324-6564 to start a conversation or visit Echologics.com.

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PUMPS optimal performance, while operating at much higher pressures than conventional single tube designs. The multitube design delivers tube life up to four times longer than average single tubes. FLEXFLO peristaltic pumps are equipped with Blue-White’s exclusive patented, built-in tube failure detection system (TFD). This technology detects a wide range of conductive chemicals with no false triggering. If the TFD detects tube failure, the pump will automatically shut off and energize a relay switch. This permits communication with external equipment, such as a back-up pump or alarm. It also serves to prevent chemical spills and added downtime. FLEXFLO pumps can be equipped with Blue-White’s quick disconnect fittings. They are designed to help ensure operator safety by helping prevent chemical spills and splashing. Quick disconnects allow an operator to safely and quickly disconnect the metering pump. The RED outlet/discharge fitting has an automatic (active) functioning check valve, preventing chemical backflow. The NATURAL inlet/suction fitting functions as a check valve when tubing is detached, preventing loss of prime and spills, while changing the tubing assembly. The valve is forced open when the tubing assembly is attached. Other features include clamp-less

A peristalic pump dosing setup used by a brewing company to assist with its wastewater treatment.

over-molded tube fittings, two CNC machined rollers and two alignment rollers for optimum squeeze and tube life. The maximum working pressure is up to 125 psi / 8.6 bar with a 2500:1

turndown ratio. Units are NEMA 4X / lP66 rated. Jean Hendrickson is with Blue-White Industries. Email: info@blue-white.com

Building Better Communities Located in historic Dawson City, Yukon, the community’s new water treatment plant employs cartridge filtration technology, followed by ultraviolet and chlorine gas disinfection, and features solar photovoltaics and local biomass energy. The selection jury for this award-winning design was “impressed with the simple, yet efficient filtration solution developed by the project team using locally sourced material and trades”. An employee-owned, Canadian consulting firm, Associated Engineering specializes in the water, transportation, infrastructure, environmental, energy, and building sectors. Our holistic approach considers climate change impacts to create sustainable and Dawson City Water Treatment Plant Project Captures Canadian Consulting Engineering’s Award of Excellence

resilient solutions.

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24 | June 2021

Environmental Science & Engineering Magazine

STORMWATER

Deployment of first layer of Geoweb cellular confinement over RS280i high efficiency geotextile.

Constructing a new child care facility directly above its stormwater system By Justin Gouthreau

uring the construction of the Mount Dennis Child Care Facility, Toronto’s largest and first net-zero childcare facility, the contractor faced significant challenges due to available space for staging and construction sequencing. They needed to operate a crane with outriggers during the building construction. The only space available on-site was directly above the belowground stormwater system, which needed to be installed in the early stages of construction. A solution was required to protect the stormwater tanks and reduce the ground pressure exerted by the outrigger over the tanks. The belowground stormwater infiltration system used was a Brentwood Stormtank 25 series. Its heavy-duty infiltration gallery was installed within the parking lot to collect surface water

www.esemag.com @ESEMAG

runoff and infiltrate stormwater to match pre-development conditions. This was a low profile 600-mm tank rated for HS-25 wheel loading. The point load of the outrigger was a cause for concern, and to mitigate the potential risk of damage to the system or the reduction of service life, the contractor reached out to Layfield for a solution to reduce vertical pressure above the Stormtank from the crane outriggers. Presto Geosystems provided a multilayer Geoweb system designed with Atra Keys & Clips to create a safe working pad beneath the outrigger. It is an advanced soil stabilization technology that confines infill material and controls shearing and lateral and vertical movement of infill material. The Geoweb system’s effect is immediate and works on the principle of hoop strength. It’s designed cross section included a layer of RS280i high-efficiency woven geotextile below two layers of GW30V6 150-mm cellular con-

finement Geoweb , infilled with 20-mm crushed granular and topped off with a crane outrigger pad. The RS280i provided reinforcement, delineation and separation between the pad layer while the Geoweb provided confinement of the 20-mm crushed aggregate compacted fill material. This concept reduced vertical pressure from the crane outrigger to well within the HS-25 loading limit of the storm tank system. Installation of the system was efficient and took approximately one day to complete. The contractor was delighted with the ease of use and installation to address this challenge and comfort, knowing the below-ground storage tank was protected.

Justin Gouthreau is with Layfield Geosynthetics. Email: justin.gouthreau@layfieldgroup.com

June 2021 | 25

WATER

Determining when it is time to replace reverse osmosis membranes By Wes Byrne

n the surface, it might seem that knowing when to replace the membrane elements in a reverse osmosis (RO) system would be simple. In attempting to keep it that way, many companies will use one or more of the following guidelines for replacing their membrane: • Often it is after three years, which is when membrane manufacturers’ warranties end. • There is an increase in RO permeate conductivity, as related to its water quality requirement. • A designated reduction in the permeate/product flow rate occurs, as related to water demand. However, the reliance on simple limits may result in replacing the membrane prematurely. RO membrane elements have been known to last more than ten years, while still providing salt rejection and permeate flow rates similar to what they produced at startup. Performance deterioration caused by membrane age occurs so slowly, that age itself rarely plays much of a role in the life of the membrane. Rather, replacement is more often related to how well the RO system is maintained. If a strong oxidant like free chlorine contacts the RO membrane, it may dramatically reduce membrane life. It should be understood that any exposure to free chlorine will damage the RO membrane. The extent of damage will be related to the chlorine concentration and the amount of time it is in contact with the membrane. With continued exposure, RO salt rejection will decline and the permeate flow rate will increase. The extent of this is best gauged by normalizing the permeate flow rate for any changes in water temperature and operating pressures. If there has been an unacceptable decline in salt rejection that has occurred simultaneously with an increase in normalized permeate flow rate, it usually means that all of the membrane elements will need to be replaced. This includes those in a second pass if they received chlorinated permeate water from the first pass. Before assuming that all of the membrane elements need to be replaced, more insight can be gained by measuring the conductivity of the permeate water from each membrane vessel. Some rejection problems may be corrected by replacing only the membrane elements located in specific locations within the membrane vessel array, such as in the very lead end, when there is excessive fouling caused by suspended solids in the inlet water. Poor performance from the concentrate-end vessels could be a symptom of scale formation, or it might simply be related to warmer water temperature when using a low energy RO membrane. If the RO salt rejection declines, profile the membrane ves26 | June 2021

Excessive fouling is the most common cause of reduced membrane life.

sel permeate conductivities to isolate the location of the problem and where membrane elements may need replacement. Excessive fouling is the most common cause of reduced membrane life, which can be defined as allowing the RO feed-to-concentrate pressure drop to increase more than 15%, or the normalized permeate flow rate to decline more than 15%. If biological particles and/or silicate clay particles are allowed to collect and compact against the membrane surface, it will take longer for cleaning solutions to wet out and completely remove them. If larger particles are allowed to collect and plug off the flow channels through the membrane elements, the cleaning solution will not be able to access those fouled regions. If cleaning does not restore the original feed-to-concentrate pressure drop or normalized permeate flow rate, then more aggressive cleaning may be needed. This is more easily accomplished off-site. Membrane surface fouling will cause the normalized permeate flow rate to decline. Fouling is usually most severe in the lead-end membrane elements, due to their higher permeate flow production. As these elements lose permeation, downstream membrane elements are forced to produce more water and subsequently suffer from increased fouling. The inability to restore the normalized permeate flow rate with aggressive cleaning usually indicates that all of the (firstpass) membrane elements will need to be replaced. Large biological particles can be shed into the RO feed water from biofilm present in the piping and system components located after dechlorination. These particles can get caught Environmental Science & Engineering Magazine

within the membrane spacing material of the lead-end membrane elements. This is more common with older RO membrane models that use a thinner spacing material than the 34 mil spacing that is now used. They will cause the lead elements’ feed-to-concentrate pressure drop to increase, as well as across all the elements within their first-stage pressure vessels. If the pressure drop across the stage exceeds 60 psi, it can crush the concentrate-end membrane elements within the vessels. If the first-stage pressure drop has not exceeded 60 psi, the problem can be corrected by replacing only the lead-end membrane elements. If an excessive pressure drop is allowed to occur, crushed concentrate-end membrane elements in the vessels may also need to be replaced. A scale formation event can occur quickly for a number of different reasons, including the failure of a chemical injection pump or due to a poor upstream softener regeneration. Many types of scale/salts will cause the last-stage pressure drop to increase. On-site cleaning is often successful if the scale is primarily composed of calcium carbonate. This will cause a substantial increase in the permeate conductivity from the affected membrane vessels. Sulfate scale is far less soluble than carbonates and its presence may result in the need to replace the concentrate-end membrane elements. When scale formation causes an increase in the RO last-stage pressure drop that is not restored by cleaning, only the concentrate-end membrane elements will need to be replaced to restore original performance. Silica scale formation may occur in geographic regions where the water source contains a dissolved silica concentration greater than 40 mg/L and the water temperature is somewhat cool. This type of scale will blind the membrane surface in the downstream elements, causing the normalized permeate flow rate to decline. As the concentrate-end membrane elements blind off in their permeation, the scale formation will work its way upstream as other elements are forced to produce more permeate. With silica scale, the concentrate-end www.esemag.com @ESEMAG

membrane elements will need to be replaced, the replaced percentage of the total being roughly proportional to the percentage decline in normalized permeate flow rate. Knowing why RO performance has declined and which membrane elements are compromised will reduce the number of membrane elements that need to be replaced. It will also make it possible to modify RO pretreatment, or pos-

sibly cleaning frequency. These factors can increase the life of the remaining and newly replaced membrane elements. If the specific mode of failure cannot be readily determined, the cost of a membrane autopsy would likely be justified. Wes Byrne is with Kurita America. For more information, visit: www.kuritaamerica.com

The Only Proven In Situ Treatment for PFAS Over 16 PFAS Sites Remediated To-Date, With 143 in Progress Learn More at: www.pfastreatment.org www.REGENESIS.com

June 2021 | 27

GROUNDWATER REMEDIATION

Treatment options for PFAS contaminated groundwater By Ryan Moore

er- and polyfluoroalkyl substances (PFAS) are a class of chemical compounds that have been used in the manufacturing of a wide variety of consumer products since the 1940s. These compounds have recently come under scrutiny for their persistence, toxicity and the potential risk to human health and the environment. Studies have linked exposure to these “forever chemicals” to several cancers, developmental problems, thyroid, kidney and liver diseases, and immune system malfunctions. Due to growing public awareness and an evolving political climate, widespread changes to government regulations and enforcement are imminent. The following are a few common everyday items that may contain PFAS: • Carpets and upholstery • Dental floss • Makeup • Water-resistant clothing • Child car seats • Non-stick cookware • Pizza boxes, carry-out food wrapping • Microwave popcorn Researchers are finding PFAS in a number of places. Bald eagle eggs were collected from the Great Lakes area and analyzed from 2000 to 2012. Numerous PFAS compounds were detected. The study also noted that bald eagle eggs from breeding areas located within a few miles of a Great Lake shoreline or tributary had significantly higher total PFAS concentrations than those from breeding areas located further away. Polar bears are the Arctic’s top predator, and PFAS are known to bioaccumulate throughout the Arctic marine ecosystem. For years, biologists have been studying the accumulation of organic pollutants in polar bears from Eastern Greenland. More recent studies have focused on PFAS occurrence in different polar bear tissues, including brain tissue. 28 | June 2021

Figure depicting an in situ colloidal activated carbon permeable reactive barrier preventing migration of PFAS to sensitive receptors.

The study results showed PFAS occurrence in all brain regions, especially the longer-chain PFAS compounds that more easily lodge into the fatty brain-tissue cells. In 2018, a dairy farmer in New Mexico received notice that his dairy cows may have been contaminated with PFAS after investigations at a nearby military installation revealed high concentrations of PFAS that had migrated to a wellfield supplying water to his farm and the town. USDA testing confirmed that the affected cows’ milk contained PFAS levels approaching 100 times more than the EPA’s health advisory. PFAS IN OUR BLOOD According to data from the U.S. Centers for Disease Control (CDC), PFAS is found in almost all Americans’ blood, regardless of age, race or gender. According to the CDC, “human health effects

from PFCs at low environmental doses or at bio-monitored levels from low environmental exposures are unknown.” This statement should not be taken as reassurance, however, as the average total PFAS in blood serum currently exceeds 5,000 parts per trillion (five parts per billion). Trends over time indicate these levels are slowly decreasing as PFAS materials are gradually phased out of manufacturing. Nevertheless, there is much work to be done to identify and remove the sources contributing to PFAS in our blood. PFAS IN GROUNDWATER PFAS did not originate in groundwater. They are manmade chemicals contaminating it after nearly 80 years of uncontrolled spills, PFAS-laden air and water discharges and dumping. As PFAS continued overleaf…

Environmental Science & Engineering Magazine

REINVENTING THE CHEMICAL DOSING SYSTEM The DICE Dosing Module, by Meunier Technologies, integrates all the necessary discharge components required for a typical chemical dosing system. The block type design allows for a rigid, compact and reliable product, and the significantly reduced number of connections greatly decreases leakage potential. The module allows for better precision and protection in the dosing system, and also features great quality due to its machined fabrication. The Dosing Module overcomes the many fundamental problems of the current piping system design: • Poor quality of the piping connections; • Many potential leakage points; and • Excessive vibration caused by the pump pulsation – which leads to mechanical fatigue on connections and components. Other features include: • Integrated: ° Ball valves for outlet, calibration column, and drainage; ° Auxiliary ports: pulsation dampener, washing port, transport/dilution water and secondary pumps; ° Adjustable back pressure valve; ° Adjustable pressure relief valve; ° Pressure gauge with isolator; and ° Standard design that fits all your essential needs. • Extensive reliability and durability; • No threaded or glued connections; • Extremely compact design resulting in minimal footprint; • With only 3 supporting bolts and 4 connections, the module can easily be installed on new and existing systems (retrofit); • Possibility of having only 1 Dosing module for 3 pumps (1 injection point, 3 pumps); and • Capability of calibrating the pump with the correct suction head and discharge pressure.

Before

Now

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GROUNDWATER REMEDIATION compounds were not regulated, most of these activities were not illegal. PFAS concentrations in groundwater are mostly below the current health advisories. However, many communities’ and single-well owner water supplies are currently being threatened by these groundwater compounds at much higher levels. Most remain unaware, since these wells have not yet been tested for PFAS. APPROACHES FOR TREATING PFAS CONTAMINATED GROUNDWATER There are two general types of approaches currently employed to treat PFAS-contaminated groundwater: ex situ and in situ. Ex situ treatments mostly involve mechanical groundwater extraction and filtration using granular activated carbon (GAC). Pump and treat (P&T) systems have been reliably used to prevent migration of organic contaminant plumes in groundwater for decades. If properly constructed, a line of extraction wells can form an impassive flow boundary that PFAS or other contaminants cannot cross. Like all mechanical systems, P&T systems must be maintained to ensure effective operation. Part of the maintenance required for them includes routine sampling of treated water to demonstrate PFAS removal effectiveness, and changing out of the spent carbon. As governments designate certain PFAS compounds as hazardous substances, spent carbon materials will have to be managed as hazardous waste, resulting in significant cost increases to maintain these systems. More recently, groundwater scientists have adopted an in situ PFAS treatment method. This approach uses a colloidal form of activated carbon applied directly into the groundwater. The colloidal activated carbon (CAC) treatment works by intercepting contaminants that move naturally through established groundwater pathways. To accomplish this, CAC is injected along a line of delivery points into the affected aquifer zone to form a permeable reactive barrier (PRB). As groundwater migrates across the PRB, PFAS sorbs onto the carbon, resulting in clean water discharge from the barrier’s down30 | June 2021

Micro-scale image showing CAC coating individual sand grains.

gradient edge. Thereby, the potential exposure to these chemicals is eliminated, and so is the risk. Material scientists developed CAC to overcome evenly dispersing a solid injected material (i.e., activated carbon) through aquifer soils. This required carbon particles to be ground to 1 to 2 microns, equivalent in size to a red blood cell and small enough to fit through soil pores. However, due to hydrostatic forces that result in particle agglomeration (i.e., clumping), merely shrinking their particle size will not allow carbon to pass through soil pores. This requires forming the carbon as a colloidal suspension, made possible by the use of a proprietary, drinking-water safe, anti-clumping treatment that cloaks the surface charge of the particles. The result is that as CAC is injected, it moves through the soil pores but also coats them with a thin carbon layer that encapsulates the individual soil grains, in effect painting them with carbon. In situ CAC treatments have been used to capture and treat groundwater contaminants since 2014 and applied at numerous PFAS-contaminated groundwater sites. More than one hundred PFAS projects are currently in the implementation or planning stages. The longest-running application has

reduced PFAS for five years, with the treatment expected to be maintained for 50 years, based on independent, peer-reviewed modeling estimates. In a cost-comparison analysis, this particular treatment was 17 times less expensive than implementing an ex situ P&T approach. CONCLUSIONS While PFAS exposures in daily life may be managed over time through conscious purchasing decisions, PFAS in groundwater will remain an invisible threat to millions for many years to come. However, there are reliable ex situ and in situ methods to safely address this threat. Ryan Moore is with Regenesis. Email: rmoore@regenesis.com (References available upon request.)

Environmental Science & Engineering Magazine

WATER

Collingwood halts construction as it discovers water demand outpacing capacity

s the Ontario Town of Collingwood pauses local construction for a year to assess its dwindling drinking water and wastewater treatment capacity, local officials are also revisiting the amount of water the town supplies to neighbouring municipalities. The ongoing process is tied to understanding Collingwood’s growth potential amid a recent significant increase in development applications. An Environmental Assessment has been completed for the expansion of Collingwood’s Raymond A. Barker Water Treatment Plant, local officials say, but the build will not be completed until 2025. In the meantime, Collingwood town council has approved an interim control bylaw that restricts development which does not already have a building permit, in part to conserve water. “We’ve recently confirmed that the demand for drinking water is greater than the supply,” Collingwood’s Chief Administrative Officer Sonya Skinner told town council at an April meeting. “Some of the questions that have been brought forward, and rightfully, is why didn’t we know this sooner,” she added. Town staff are also in discussions with the Town of New Tecumseth and the Town of the Blue Mountains to potentially reduce the amount of water supplied to these municipalities until the water treatment plant expansion is complete. “Council deliberated at length, and considered all the information provided by staff, our solicitors, the deputations this evening, and written submissions, before coming to a very difficult decision that we all know will have significant impacts in the community,” announced Collingwood Mayor Brian Saunderson in a statement. “However, the implications of not taking this pause on development were potentially much more severe. This is not our first choice, but we are in a situation that demands action,” he added. In addition to expanding the water www.esemag.com @ESEMAG

Photo of Collingwood. Town staff are in discussions with the Town of New Tecumseth and the Town of the Blue Mountains to potentially reduce the amount of water supplied to these municipalities until the water treatment plant expansion is complete. Photo Credit: Ryan / Adobe Stock

treatment plant, built in 1998, town officials also want to advance construction of a chlorine contact tank that will increase capacity. A review of the plant’s disinfection calculations in 2018 determined that the town was approaching the upper limit of the existing WTP’s disinfection capabilities during winter, while remaining within drinking water quality aesthetic targets for chlorine. In terms of drinking water, the rated capacity of the Collingwood WTP is 31,140 m3/day. However, this capacity is not available in the winter months due to limited chlorine contact tankage at the plant. Planned expansion would take the plant to a capacity of 51,871 m3 per day. A new chlorine tank would allow the plant to operate at its full rate capacity under all temperature and raw water conditions, “while providing the required disinfection by chlorination without increasing the potential for taste and odour concerns by customers,” town staff wrote. The annual average day flow at Collingwood’s wastewater treatment plant from 2018 through 2020 is nearing the 80% trigger for warranting expansion, according to a town staff report.

Collingwood also has water supply agreements with the Town of New Tecumseth and the Town of the Blue Mountains. Water supply agreements with these neighbouring municipalities account for approximately 35% of the rated capacity of the water treatment plant. When the winter constraints of the disinfection infrastructure are taken into consideration, these agreements result in a commitment of more than 50% of the treatment capacity of the water treatment plant. Over the past five years, the combined water demand from all three municipalities has fluctuated, with a fiveyear average of 24,049 m3 per day. Current water supply agreements are leading to an “overcommitment” in the winter months, according to town staff. “Although these calculations indicate that there is insufficient water supply to service existing customers and future development while waiting for the WTP expansion to be completed, there are solutions that can be implemented to mitigate the water supply capacity issue in the interim,” states a report by Peggy Slama, Director of Public Works, Engineering & Environmental Services for the Town of Collingwood. June 2021 | 31

WATER

Strategies to increase existing reverse osmosis unit output By Ron Gouthro and Ken Rilling

ircumstances may dictate that a facility meet an increased reverse osmosis (RO) demand from an existing unit that is already at capacity, with no impact on quality. Approaches for achieving this goal are outlined in this article. Two cases are reviewed where existing RO units were modified to meet increased RO water demand. RO normalization and maintenance is reviewed in Section 2 to emphasize how these steps achieve ongoing RO performance requirements. Pretreatment of source water to provide suitable membrane feed water quality is described in Section 3, along with associated water consumption and maintenance.

32 | June 2021

DEMONSTRATING INCREASED OUTPUT FROM EXISTING RO UNITS In case one, RO water generation doubled, and recovery increased from 70% to 75% for an existing RO unit. This was achieved by membrane addition, revised staging of membrane modules, and adjustment of concentrate-recycle flow. The staging configuration design was 2:1 ratio of pressure vessel (PV) with four membrane elements per PV applied. The RO membranes selected within each PV ensured interstage hydraulic balancing. The concentrate recycle flow setting optimized water recovery with hydraulic balancing. In this case, the source water is municipal drinking water. First, it was determined that the existing granular activated carbon (GAC) vessels had the capacity to dechlorinate source water at

a higher feed flow. In order for the GAC to provide this, it was emphasized that the GAC media sterilization and backwashing be performed as required. The following additional steps were taken: • For hardness removal by antiscalant dosing, the existing pump was replaced with a metering pump, to minimize pulsed dosing of antiscalant. • Added an ultrasonic level sensor with transmitter. • Sent the level signal to the RO unit panel with programmable logic control to generate alarms on low antiscalant level in the drum. In case two, recovery increased from 70% to 80% to meet the plant’s increased RO water demand. This was achieved by modifying the number of stages, number of PV per stage, number of membranes per PV, and arrangement of RO mem-

Environmental Science & Engineering Magazine

Normalization Values

Trending from Baseline or Standard

Normalized Permeate Flow (PFn)

Decreasing

Membrane fouling and/or scaling

Consult knowledgeable membrane rep for cleaning procedure

Increasing

Deterioration of the RO membrane thin-film composite layer

Test RO feed water to determine free chlorine level, calibrate ORP probe if part of RO unit

Leak in an O-Ring seal at interconnector and/or endcap

Review with knowledgeable membrane rep

Increasing

Membrane fouling and/or scaling

Consult knowledgeable membrane rep for cleaning procedure

Decreasing

Failed instrumentation

Diagnose instrument issue see instrument manual and/or consult supplier

Decreasing

Scaling and/or membrane degradation

Consult knowledgeable membrane rep for next steps

Increasing

Biofilm formation plugging pinholes in membrane

Consult knowledgeable membrane rep for next steps

Normalized Pressure Differential (DPn)

Normalized Salt Rejection (SRn)

Cause

Maintenance

Table 1. Reverse osmosis normalization and maintenance.

brane type (flux and pressure drop). Judi- data for feed, permeate and concentrate cious application of concentrate recycling is collected to measure pressure, flow acted to hydraulically balance membrane and conductivity of all three values. flux, resulting in minimization of fouling. Most RO membrane manufacturers provide software or an Excel spreadRO NORMALIZATION sheet to generate calculated normalized AND MAINTENANCE values from entered data. Trending and The objective of RO normalization is percent change from baseline is calcuto determine when to address RO mem- lated to determine any action required. brane issues before irreversible damage The suggested actions based on trends occurs. This routine measure minimizes in normalized values below are summaboth downtime and operating costs. rized in Table 1. Normalization accounts for the impact of operating conditions, such as feed NORMALIZED PERMEATE water composition, temperature and sys- FLOW (PFN) tem pressures on permeate flow, quality A decreasing trend in PFn may be due and recovery. For example, a 5°C increase to membrane fouling and/or scaling. in source water temperature generates a Decreases of more than 10% from basepermeate flow increase of approximately line value indicate membranes should 10%, with other parameters constant. be cleaned. Proper membrane cleaning If RO performance values are not is critical in restoring membrane perfornormalized, the raw data can mislead mance and should be reviewed with a the operator, and incorrect decisions knowledgeable resource. can lead to unnecessary operating costs. For example, membranes in the first Equations are available to adjust nor- stage are commonly fouled by organics malized values to a standard or base- and/or bacteria. In this situation, first line to account for differences in oper- stage membrane pressure vessels should ating conditions. The normalized values be isolated and cleaned with a caustic include: permeate flow (PFn), normal- and surfactant solution at a basic pH. ized pressure differential (DPn), and Membrane cleaning procedure considnormalized salt rejection (SRn). ers soak time, recirculation time, and Baseline operation can be at start-up replacement of cleaning solution if it or membrane replacement. Operating becomes cloudy or discoloured. www.esemag.com @ESEMAG

The second stage is commonly fouled due to scaling and the cleaning chemicals include an acid at low pH. An increasing trend in PFn infers either deterioration of the RO membrane thin-film composite layer due to chemical attack by free chlorine, or a leak in an O-ring seal at interconnector and/or endcap. RO feed water should be tested to determine free chlorine level and, if the RO unit is equipped with an ORP probe, it should be calibrated. If free chlorine exceeds allowable continuous exposure limit, then troubleshooting includes unit operation for free chlorine reduction. NORMALIZED PRESSURE DIFFERENTIAL (DPN) Feed spacers in the RO membranes are susceptible to fouling and this is observed by change in DPn. Membranes should be cleaned when DPn increases 10% to 25% from baseline. Measuring DPn between stages is advantageous because first stage fouling is likely due to organics and/or bacteria, whereas second stage fouling is due to scaling. A decreasing trend in DPn may be due to failed instrumentation. continued overleaf… June 2021 | 33

WATER NORMALIZED SALT REJECTION (SRN) Decreasing trends in SRn can be due to scaling and/or membrane degradation. An increase in SRn can be due to biofilm formation as the biofilm can plug pinholes in the membrane. PRETREATMENT APPROACHES The impact of source water quality on RO membranes includes fouling due to scaling, bacteria, biofilm and organics, as well as chemical degradation of the membrane due to the presence of oxidizing agents. Pretreatment unit operations for minimizing scaling are water softeners and antiscalant. Softeners replace cations that scale with sodium. A drawback is water use for regenerating cation exchange resin, along with maintaining salt levels in the brine tank. Maintenance should include regular checking of hardness levels in softened water. Antiscalant dosing is an economic approach to inhibit scaling with no gen-

eration of wastewater. Capital cost for dosing antiscalant includes a metering pump that is activated when RO is operating. To minimize the risk of running out of antiscalant, it is recommended that a level transmitter be utilized on the container to alarm on low level. By informing the antiscalant supplier about source water quality and RO unit details they can generate projections on recommended antiscalant and required dosing. DECHLORINATION APPROACHES Polyamide RO membranes are susceptible to degradation by oxidizing agents such as hypochlorite and chloramines that are applied in municipal potable water for disinfection. The removal of free chlorine, hypochlorite and chloramines from source water can be achieved by GAC, sodium bisulphite (SBS), and ultraviolet light (UV). Granular activated carbon (GAC) is only effective as pretreatment to RO membranes when properly maintained.

Weekly sanitization of GAC in carbon towers either by steam or hot water is recommended to remove buildup of bacteria, biofilm and organics. Regular backwashing of GAC media in downflow filters is also recommended and usually applied after steam or hot water sanitization. Backwashing GAC media removes fines (sub-micron size particulates) that accumulate and loosens the media as it compresses with time. Fines can be present in the municipal potable water and from breakdown of GAC particles. The accumulation of fines and media compression causes water flow to channel in the GAC, resulting in reduced contact time and effective surface area of GAC. Breakthrough of free chlorine and other disinfectants can be a consequence of flow channeling. Increased pressure drop across the carbon tower can be due to flow channelling and biofouling. Annual replacement of GAC is recommended. A cost-effective option to new GAC is its reactivation. This service is provided by some activated carbon suppliers.

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34 | June 2021

Environmental Science & Engineering Magazine

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Sodium meta bisulphite (SMBS) is used as a dechlorinating and biostatic agent. Common practice is to generate stock aqueous sodium bisulfite (SBS) solutions from SMBS. SBS solutions have an effective shelf life as SBS is oxidized by air. The rate of this oxidation reaction is a function of SBS concentration where oxidation rate increases with increase in SBS concentration. Measures to reduce this impact include an inert buoyant barrier in the SBS solution storage tank, such as styrofoam. Stoichiometrically, 1.34 mg of SMBS is required to reduce 1 mg of free chlorine, but operations have shown up to 3 mg of SMBS being required. A static mixer is normally applied in the water line downstream from where the SBS solution is dosed, to ensure thorough mixing. Due to the required SBS concentration in stock solutions and resulting volume to dose, SMBS is generally applied in larger RO systems such as those with 200-mm diameter membranes. The selection of metering pumps in these applications allows for SBS dosing with minimal pulsed flow. In systems with 100-mm RO membranes and smaller, the dosing pumps generate a more exaggerated pulsed dosed volume of SBS solution, resulting in under and over dosing of SBS solution in the water. The RO membrane is then susceptible to repeated chemical degradation due to exposure to free chlorine and other oxidizing agents. The benefits of SMBS are minimal operating and capital costs, and no wastewater generation. Dechlorination by ultraviolet treatment (UV) is gaining acceptance because of successful water treatment applications in manufacturing, pharmaceutical, food and beverage, and semiconductors. The UV dosage required for free chlorine reduction and chloramine dissociation is many times higher than that needed for UV disinfection. This high UV dose will also reduce organic compounds that are present. To achieve one (1) log reduction in free chlorine, a 600 mJ/ cm2 UV dosage is required. No wastewater and relatively minimal maintenance are also advantages. Process information for sizing the UV unit include feed water flow, transmittance, and organics concentration, as well as free chlorine level at inlet and required removal amount. C

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SUMMARY Optimization of an existing RO unit may be achieved through membrane selection, PV staging ratio, and hydraulic balancing. Continuous optimization of RO unit performance and operating cost minimization requires RO normalization with timely maintenance based on magnitude of changes in the normalized values (PFn, DPn, SRn). The review of source water pretreatment provides direction for unit operations, including awareness of wastewater generation and the relative operating costs. Ron Gouthro and Ken Rilling are with PREtreat Water Inc. Email: ron.gouthro@pretreatwater.com, ken.rilling@pretreatwater.com

www.esemag.com @ESEMAG

June 2021 | 35

SPECIAL FOCUS: STORAGE TANKS, SPILLS & CONTAINMENT

Measurement methods for chemical storage tank inventory calculation By Greg Tischler

T The radar sensor is mounted above the polypropylene tank, eliminating the need for an additional process connection.

he compositions of chemicals in use today are as diverse as the manufacturers and the distributers who ensure there is a steady supply for consumers and industry alike. Likewise, the technology these companies use to measure and manage their chemical inventories can be just as diverse. These facilities have an array of options for measuring the amount of chemicals inside their tanks. One large chemical manufacturer and distributor had previously been using weigh scales installed beneath every tank and vessel. However, they recently switched to high frequency through-air radar sensors.

WEIGH SCALES: THE CLASSIC MEASUREMENT Weigh scales, sometimes referred to as load cells, are widely used for measuring inventory in large tanks. These scales are installed under a chemical tank to make a weight measurement. Using this measurement and a known density, the sensor electronics can output a volume to help facilities better manage their inventory. Weigh scale technology is easy to understand, and it works. A weight measurement is made mechanically, which can easily be calculated into an accurate volume measurement using a known density and a simple formula. Since weigh scales have no contact with the medium being measured, these sensors can measure any liquid chemical despite corrosive or harmful properties. Straightforward measurement, however, is where the simplicity ends. Installation alone can be costly, time-consuming, and labour-intensive. Installing a single system means lifting the entire vessel and placing the weigh scale underneath. Shutting down a process or taking a vessel out of use, if necessary, only increases costs further. Weigh scales can also be expensive to maintain. These instruments make a mechanical measurement, so they need to be regularly cleaned, recalibrated, and repaired. All of this takes valuable time for maintenance crews, yet for many facilities, this process has become routine. Every few months, vessels are taken out of service, so maintenance crews can inspect and recalibrate the instrumentation. HIGH FREQUENCY RADAR MEASUREMENT Through-air radar works by emitting radio microwaves from the radar antenna system to the measured prod-

36 | June 2021

Environmental Science & Engineering Magazine

uct, where it is reflected by the product surface and back to the antenna system. The radar sensor uses time of flight to measure the level of the product. Radar sensor electronics can use the level measurement and the vessel geometry to calculate product volume inside the tank. The real-world benefits of high frequency 80 GHz radar can be seen in an array of applications, including chemical tanks. Radar sensors with 80 GHz frequency have enhanced focusing, the ability to make measurements through plastic vessels, and special software to generate an accurate and reliable echo curve to interpret the level inside the vessel. A radar beam’s focus is dependent on two factors: the size of the radar transmitter’s antenna and its transmission frequency. A smaller antenna or a lower frequency results in a wider, less focused beam. Conversely, a larger antenna or a higher frequency results in a narrower, more focused signal. Therefore, a radar sensor using a high 80 GHz frequency can accurately measure in small or narrow vessels, with little to no interference. Radar signals can also penetrate non-conductive products like plastic and fibreglass. Since many chemicals are stored in tanks made of polyethylene, commonly referred to as poly tanks, an 80 GHz radar sensor can simply be installed above these tanks, without the need for an additional process connection. This simplifies and decreases the costs associated with installation. The intelligent electronics within today’s 80 GHz radar sensors multitask to meet individual user’s needs. In their most basic function, the electronics output a level measurement, but they can also calculate a volume measurement using known vessel geometries. Those same electronics can even filter out signal interference from condensation, or dust and dirt built up on the antenna, so there is no need for regular maintenance, cleaning, or recalibrations.

this facility ranged in size from small portable tanks to large vessels capable of holding thousands of litres. Over time, measurements would drift, which resulted in slight measurement errors at best, and dangerous, costly spills at worst. Plus, whenever the facility needed to move a tank, the weigh scale sensors would have to be recalibrated and recertified. The cost of maintaining all the weigh scales was growing. After exploring the available measurement options, operators at the facility chose the VEGAPULS C 11. This 80 GHz radar sensor has a fixed cable connection attached to a chemical-resistant PVDF housing. Installation was inexpensive and straightforward. Maintenance staff simply installed some of the radars in existing process connections on top of the tanks, or hung the radar above the poly tank and measured through the top of the vessel.

BETTER RESULTS WITH BETTER TECHNOLOGY Installing the new VEGAPULS C 11 radar sensors resulted in accurate measurements, which eliminated inventory errors, overfilling, and safety concerns related to incorrect measurements. The new radar sensors provided accurate volumetric measurement outputs without the need for ongoing maintenance. A simple swap of measurement instrumentation improved operational efficiency and safety records. Now, the company is moving forward with plans to standardize the measurement instrumentation at their other facilities. Greg Tischler is with Vega Americas. For more information contact VEGA Instruments Canada. Email: canadaquotes@vega.com

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SPECIAL FOCUS: STORAGE TANKS, SPILLS & CONTAINMENT

Creating a safe chemical storage system By Marshall Lampson and Bill Kerschbaum

hether you’re an engineer writing a spec for a chemical storage system, or an end user who is looking for the best way to store corrosive chemicals, there are multiple factors that go into creating a safe storage system. Cost might be your first consideration, but there is more to consider than the initial price of the tank, its fittings and accessories, delivery, installation and tank longevity. It is important to consider the durability and longevity of the tank system when you’re storing corrosive chemicals. In fact, every good tank design starts by considering the chemical you’re storing. Everything else flows out of that. Leaks and degradation can be costly to repair. It is even more costly when a tank system has to be replaced because it wasn’t engineered to store corrosive materials.

WHICH CHEMICALS ARE CORROSIVE? A corrosive chemical is one that will damage or destroy another substance upon contact. In most cases, the higher the concentration, the more corrosive it is. It can cause chemical burns to live tissue, and the chemical fumes can cause eye and lung irritation or damage. Both acids and bases can be corrosive. Some commonly stored corrosive chemicals include peracetic acid, sulfuric acid, hydrochloric acid, sodium hypochlorite, nitric acid and sodium hydroxide. Many of these chemicals can corrode metal, especially at higher temperatures. When metals corrode because of these substances, they often give off a hydrogen gas which is flammable. If you are storing chemicals in a plastic tank, there is little to no metal to corrode and you are protected from these hazardous fumes. Polyethylene is a durable plastic that is available in medium-density, high-density (HDPE) and high-density cross-linked (XLPE) forms. Medium- and high-density polyethylene are usually linear, which means that the 38 | June 2021

To extend longevity, you can store corrosive oxidizing chemicals in an XLPE tank with an antioxidant barrier system.

polymers of the plastic are joined in a twisted formation like rope fibres, rather than knotted in nature. XLPE is created in a way that the very molecules of the plastic are bonded and linked. Imagine a chain-link fence where the metal is actually linked together. These factors mean chemical resistance, heat resistance and dimensional stability are very high. Cross-linked polyethylene has covalent bonds that connect its polymer chains. These bonds tie the polymers together and lengthen the polymer chains, giving the polyethylene stronger resistance to impact and a longer life. The molecular structure provides stress-cracking resistance, improved toughness, and in many cases much greater useful life. The implications of these differences are most obvious when testing plastics. When linear polyethylene fails, it can fail catastrophically, because the linear polymer chains tend to “unzip”. In some

cases, the entire tank comes undone, and a small leak becomes a chemical spill. All of the stored product could be lost, and cleanup can be considerable. On the other hand, cross-linked polyethylene might develop a small pinhole or tear, but the chances of a catastrophic failure are extremely low. You are not likely to lose all of the stored chemical if a leak develops, and the cost of cleanup and replacement in most cases is significantly less expensive. As well, the risk to employees and the environment can be drastically reduced. In most cases, cross-linked polyethylene offers longer useful life in the same application as linear polyethylene. Based upon feedback from customers over the last 45 years, the typical useful life of storage tanks made from XLPE is 15-20 years. However, there are factors that impact this lifespan. The types of chemicals stored, the concentrations of the chemicals, the filling frequency, and the operating temperature within the storage tank, all impact the useful life of a polyethylene storage tank. For example, a high concentration of sulfuric acid (an aggressive stress-cracking agent) will break down a tank quicker than 25% caustic soda. Or 12% sodium hypochlorite will degrade from UV exposure and elevated temperatures. As the breakdown of the chemical occurs, sludge builds up in the bottom of the tank, resulting in a potentially shorter tank life. There are several innovations available to address these two chemical storage situations. The first is the antioxidant resin systems designed to slow the aggressive breakdown from storing sulfuric acid. Another innovation is an integrally molded flanged outlet, or IMFO system. This system, with the flange molded into the bottom of the tank, permits full discharge of the tank. Sludge buildup from storing chemicals, such as sodium hypochlorite, can be easily removed without a

Environmental Science & Engineering Magazine

confined space entry, extending the useful life of the tank and keeping employees safer. Improper installation and “hard” piping are the greatest factors reducing useful tank life. Polyethylene is inherently able to expand and contract and can safely store a broad spectrum of chemicals. Proper flexible connections accommodate this tank expansion, leading to extended life of the tank. While often overlooked, proper venting plays an important role in extending tank useful life. Since polyethylene tanks are rated at atmospheric pressure, or vacuum, adequate vent size is important to accommodate flow and delivery rates. Factors to consider in determining proper venting include: • Will the tank be filled pneumatically or mechanically? • Is the tank vented to the outside atmosphere? • Is vent length longer than one metre? • Is fume scrubbing used?

Improper installation and “hard” piping can greatly reduce useful tank life. Since polyethylene is inherently able to expand and contract, proper flexible connections accommodate this tank expansion.

• Are there vent screens that restrict over pressurization? flow? Three additional factors that deter• Are emergency venting specs pro- mine storage tank useful life are convided from the manufacturer to prevent continued overleaf…

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www.esemag.com @ESEMAG

June 2021 | 39

SPECIAL FOCUS: STORAGE TANKS, SPILLS & CONTAINMENT

tinuous cycling (filling and discharge), excessive agitation in mixing and mobile applications. To extend longevity, you can store corrosive oxidizing chemicals in an XLPE tank with an antioxidant barrier system. The technology behind true antioxidant barrier systems takes the guesswork out of choosing the right storage tank system for oxidizing chemicals. Antioxidant additives are used to extend tank life. This fights off corrosion caused by oxidizing chemicals, regardless of the type of plastic. Antioxidants extend the longevity of HDPE, XLPE, nylon, and any other plastic, since they are all carbon-based. Oxidation slowly deteriorates any carbon-based bond, whether it is in a plastic, plant, or animal. One company uses a resin system made of polyethylene, but what makes it special is the 400% more antioxidant additives in that resin. It is added to the chemical tank during the roto molding process, which creates a seamless bond

between the barrier resin and the XLPE polyethylene. This unique combination of polyethylene creates an ideal containment for even the most corrosive chemicals. XLPE gives you the strength and tank longevity, while antioxidant resins give you optional additive oxidation resistance over time.

out of the building can be a large undertaking. A crew will need to disconnect the piping, pumps and other accessories. The tank will need to be pulled out of the building, or, if it is too large to pull through the doors, it will need to be cut up and removed. If the new tank is too large to maneuver through the entrance, you may need THE BEST BUSINESS DECISION to remove the paneling or roofing, and lift FOR CHEMICAL STORAGE the new tank inside the building with a There is a significant cost to installing crane. Also, the time and labour involved and replacing a chemical storage tank. with plumbing can be very costly. Many companies only calculate the tank Whether you purchase a cheap tank purchase cost and shipping costs when or an expensive tank, it is important to deciding to purchase a new tank or replace install the best chemical storage system an existing one. However, there are several for the greatest useful life. While XLPE additional factors to consider as well, tanks can have a slightly higher upfront If you need the chemical on a daily cost, the investment means fewer mainbasis, you might bring in a smaller tem- tenance costs and greater savings. porary tank while the new one is being manufactured and shipped. Sometimes Marshall Lampson is with Poly we recommend purchasing a backup Processing. Bill Kerschbaum is with Good storage tank as well, to ensure that you Gnus Marketing. For more information, have redundancy. Getting the old tank email: marketing@polyprocessing.com

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SPECIAL FOCUS: STORAGE TANKS, SPILLS & CONTAINMENT

Repairing and protecting a 1950s era wastewater digester tank By Leigh Besanger and Daryl Prefontaine

The coating program involved the wall coating application in the first phase, followed by the floor coating application in the second.

astewater treatment plant (WWTP) maintenance and upgrading programs can sometimes unearth issues that may not be apparent during regular operation. Such an occurrence happened at a WWTP consisting of eight digesters constructed at various times between 1955 and 2010. The plant had recently completed upgrades to a circa 1955 digester tank, requiring it to be taken out of service for an extended period of time, as part of ongoing maintenance and facility upgrading programs. As per code requirements, the upgraded digester had to pass a two-part tightness test, in accordance with industry requirements for environmental containment structures, before it could be returned to service. Unexpectedly, the digester did not meet the leakage specifications, so the WWTP facility management engaged RJC Engineers, a specialty structural restoration consultant, to lead the diagnosis, design, and implementation of a suitable repair program.

DIAGNOSIS PHASE The digester is one of the original structures at the WWTP. Constructed in approximately 1955 of reinforced concrete, the digester, approximately 30 metres in diameter, has a sloped conical-shaped floor, a circular perimeter wall approximately 9.5 metres high, and is enclosed with a roof slab. The bottom two-thirds of it is buried below-grade, while www.esemag.com @ESEMAG

the remaining wall portions are exposed to the exterior, or are shared with interior spaces, other buildings, or access areas at the plant. Along with the perimeter wall, 12 concrete columns support the roof structure from inside the digester’s interior. As part of the recent upgrade, an HDPE liner assembly was installed on the upper portions of the wall interior surfaces and the underside of the roof structure. It was generally assumed that the leakage was not occurring through the new liner. Therefore, the leakage repair program targeted waterproofing and protection solely on the 1950s-era concrete wall and floor surfaces below. In order to establish the potential sources of leakage and the extent of any associated concrete repair required prior to waterproofing, an initial review of the digester’s interior surfaces was performed by the consultant. The inspection uncovered many concrete issues, none of which were determined to be “the sole source of leakage”. But, all were considered during the design of the new coating assembly as potential contributors to this digester’s lack of water tightness. During this initial review, concrete cracking, cold-jointing, loose form-tie hole plugs, large areas of poorly consolidated and non-encapsulated aggregate (honeycombing), and void-ridden pour-joints with debris embedded at the interface were visually identified. Not only was it deemed important to visually identify the continued overleaf… June 2021 | 41

SPECIAL FOCUS: STORAGE TANKS, SPILLS & CONTAINMENT

various concrete issues, but establishing a likely cause of these issues was also imperative. While most of the abovenoted concrete-related issues appeared to be the result of typical (1950s) construction practice and methodology, the observed concrete cracking was thoroughly investigated. Was this cracking due to the “usual suspects” (i.e., shrinkage, reinforcing steel detailing, the original concrete mix, etc.), or was it caused by structural or thermal-related movements which would need to be accommodated by the new waterproof coating assembly? Prior to specifying and developing details for the coating, structural analysis determined that the as-constructed reinforcing steel in the digester wall was close to “on-par” with current concrete reinforcement provisions outlined by the “Requirements for Environmental Engineering Concrete Structures (ACI 350-06)”. However, thermal modelling determined that the digester wall was prone to large temperature-related stresses and cyclical/seasonal movements, due to both the internal process and exterior environment. Additionally, based upon the initial review and testing results, the pre-existing coal tar coating was likely providing some level of waterproofing and concrete protection. Unfortunately, it was no longer performing as an effective means of waterproofing/containment, likely due to its extended service life. The observed conditions substantiated the water tightness testing results and aided in defining the potential sources of leakage and repair objectives.

Voids and debris at pour-joint (bare concrete above joint, existing coal tar coating below).

Poorly consolidated and non-encapsulated aggregate.

ing polyurethane grout at pour-joint interfaces. • Provide a flexible, yet durable, chemical-resistant coating assembly capable of preventing leakage and accommodating the digester’s thermal-related movements. • Incorporate a slip-resistant texture on the sloped floor surface for safety considerations. • Maximize the remaining service life of the digester’s concrete structure. Using the results of the inspection and the defined repair criteria and objectives, RJC Engineers developed site-specific DESIGN PHASE details and specifications for the localThe project team defined the follow- ized pre-coating concrete repairs, subing objectives and criteria: strate preparation, and new waterproof• Fully remove the existing coal tar ing/protective coating assembly at the coating and any potential wastewater-re- lower interior surfaces. The design was lated contaminants from the substrate completed in the spring of 2020 and an surfaces. ambitious goal of having the digester • Remove and repair all areas of operational by year end was set. unsound concrete, including poorly consolidated and non-encapsulated aggre- SOLUTION gate to provide a suitable substrate for The coating program involved the wall coating application. coating application in the first phase, • Fill, patch, and repair all surface voids, followed by the floor coating application including localized injections of expand- in the second. 42 | June 2021

Scaffolding was constructed inside the digester for the cleaning, repair, preparation, and coating application on the lower seven vertical metres of interior wall surface (existing HDPE on the upper 2.5 metres). Once the wall coating application was completed, reviewed and tested for conformance with project specifications, the scaffolding was deconstructed and floor surface cleaning, repair, preparation and coating application phase proceeded. Cleaning and surface preparation was performed with abrasive blasting (sandblasting) followed by pressure washing. In order to fully remove the existing coal tar coating, aggressive abrasive blasting was needed. This surface cleaning and preparation method resulted in a suitably rough substrate with a concrete surface profile (CSP) greater than 5, as defined by the International Concrete Repair Institute (ICRI), for most of the 2,200 m2 of coating application area. Loose, non-encapsulated aggregate was then chipped away from the surface and patched. An epoxy mortar mix was applied to resurface and reprofile the substrate, which effectively filled all of the “peaks and valleys” of the abrasively blasted concrete. This pre-manufactured epoxy mortar mix was trowel applied to the surface to provide a uniformly textured substrate similar to CSP 3, which was the required surface profile for this coating application. After priming the resurfaced substrate, a flexible polyurethane coating was applied using a heated, plural component sprayer to the specified dry film thickness, 100 mils. The contractor performed wet mil thickness testing during application to ensure conformance with specified requirements. On the sloped floor surface, granular quartz was seeded into the wet coating with a subsequent tie-coat application to provide a slip-resistant surface. Wall and floor surface coating application mockups were specified before widespread application inside the digester. These mock-ups provided an opportunity for the project team to review and comment on the finished product and appearance, and helped establish a baseline quality expectation for the coating application.

Environmental Science & Engineering Magazine

In addition to the contractor’s quality control, quality assurance testing was performed that included adhesion strength pull-off testing and holiday/spark testing by the consultant and third-party testing agencies. After each round of holiday/spark testing, pin-hole and coating discontinuity repairs were performed and retested. Upon completion of the interior coating program, tightness testing was performed to industry requirements, and the digester passed with no measurable water loss. The WWTP facility’s goal of recommencing commissioning prior to the end of the year was achieved.

CHALLENGES RJC Engineers’ design process included identifying anticipated challenges and developing mitigation strategies with the WWTP management and the contractor during the pre-design and coordination phase of the project, which resulted in continued overleaf…

Quality Assurance testing – adhesion strength pull-off testing.

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June 2021 | 43

SPECIAL FOCUS: STORAGE TANKS, SPILLS & CONTAINMENT

very few delays during construction. However, WWTP repair and rehabilitation programs are never without site-specific surprises, so design and construction challenges were welcomed as learning breakthroughs. For instance, access to the digester interior was limited to a single 900-mm diameter access hatch, located below ground level. This meant that workers, materials, access scaffolding, and equipment passed through this small opening countless times during the project. The only equipment that was not set up inside the digester was the plural component sprayer. The contractor housed the sprayer in a trailer that was parked on an access road adjacent to the digester. There was only a 900-mm diameter access hatch into the digester. Fifty-five-gallon drums of coating were connected to the sprayer inside the trailer and hose was run from the sprayer to the facer performed poorly during pull-off Although the contractor made best point of application inside the digester. strength testing. Being a water-based efforts to keep the substrate SSD, the very During the wall surface coating assem- cementitious product, saturated-sur- thick concrete perimeter wall quickly bly mock-ups, the originally specified face-dry (SSD) was required for optimal absorbed any surface-applied water, and water-based epoxy cementitious resur- application. the resurfacing product experienced rapid moisture loss that significantly reduced material hardness and bond-interface adhesion. This water-based cementitious resurfacer had been specified based on several successful applications across North America. However, due to site-specific factors, including the digester wall being shared with interior spaces at some locations, wall thickness of approximately 760 mm, and the low humidity environment conditions at the time of the application, the originally specified resurfacing product did not perform as anticipated. Following this determination at the time of mock-ups, the choice was made to instead use a reinforced epoxy resurfacer that did not require an SSD substrate for application.

CONCLUSIONS Pinpointing the sources of leakage following tightness testing in an existing concrete containment structure can be time-consuming, costly, and in many cases, unsuccessful. Sources of leakage could be due to many design and construction factors that are addressed by “industry standards” today, but were not necessarily considerations at the time of construction. 44 | June 2021

Environmental Science & Engineering Magazine

Mix design, shrinkage cracking, cold jointing due to antiquated concrete placement limitations or techniques, pour joints, outdated formwork methods and materials, and deteriorated existing coating/liner systems are among many potential contributors to leakage. Localized sealing and patch repair attempts can become as futile as identifying the sources of leakage. When operational constraints leave a WWTP facility in a pinch, executing an interior coating program becomes one of the best options given that modern day coating assemblies are a proven means of waterproofing, containment and structural concrete protection. WWTP managers can extend the operating life of digesters by ensuring that After each round of holiday/spark testing, pin-hole and coating discontinuity repairs were identified issues are thoroughly assessed performed and retested. by specialized professionals. Repair solutions can be designed to prevent leakage, protect the structure, and provide operational performance will meet all Leigh Besanger and Daryl Prefontaine the facility management and operations requirements. are with RJC Engineers. Email: team with confidence that their asset’s lbesanger@rjc.ca, dprefontaine@rjc.ca

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June 2021 | 45

WATER

Monitoring small watersheds is vital to community safety and water sustainability By Chris Heyer

n a beautiful sunny day in July 2012, a portion of a mountainside gave way and 320,000 m3 of water, mud, rocks and trees, careened down Gar Creek, resulting in the devastating Johnsons Landing landslide in the Kootenays of British Columbia, about one hour’s drive north of the town of Kaslo. This slide destroyed four homes, seriously damaged others, and killed four people. The following day, a series of debris

Volunteer advisor Sam Lyster working on a high elevation climate station. 46 | June 2021

torrents swept down the creek, further damaging homes, narrowly missing emergency crews, residents and journalists. There were a number of factors that contributed to the event. These included a cool wet spring that kept high elevation snowpack at almost record levels in June; record precipitation in June and early July (~four times average); a sudden shift to 30°C temperatures on July 4; the presence of karst springs under the landslide site that were fed by the resulting rapid snowmelt; and highly altered bedrock that occurred in the area. This tragic event underscored what many residents and local scientists in the area already understood. “We don’t know enough about the small and medium-sized watersheds that are so important to residents, and how those watersheds will be altered by climate disruption,” said Paul Saso, hydrologist for Kootenay Watershed Science (KWS). Prior to the slide, some watershed monitoring had already been undertaken by the local community, and in other parts of the region by the Kaslo & District Community Forest Society (KDCFS). In 2016, this initiative was formally taken over by KWS (formerly known as North Kootenay Lake Water Monitoring Project). “In 2012, we simply didn’t have the data to understand our watersheds in order to adequately plan for water resource use under climate disruption or anticipate the risks that could be associated with them. The understanding of our watersheds that we are now gaining through KWS monitoring efforts will enable our communities to plan for a safer and more sustainable future as climate disruption increasingly affects our watersheds,” said Saso. Today, KWS has seven hydrometric stations, two high elevation snow course stations, two high-elevation climate stations, and one low-elevation climate station on the north end of Kootenay Lake. KWS uses a combination of professional hydrologists and volunteer citizen scientists to collect data and maintain the monitoring program. It is monitoring snow, streamflow, and climate in the Johnsons Landing area to better understand the hydrologic regime that contributed to the 2012 landslide, and identify signals that may indicate an increased risk of slides in the future. In 2019, Saso realized that using Excel spreadsheets to store and interact with data was limiting. He knew about Aquarius software, but with KWS’s small budget, they could not afford it. On a whim, he decided to email Aquatics Informatics, the developer of Aquarius. “I was sure it was a long shot and didn’t really think that they would be willing to sponsor us. However, I was thrilled when they responded, telling me about the company’s plan to launch a new grant program,” said Saso. Environmental Science & Engineering Magazine

Aquarius is an analytics software program that is used by Water Survey Canada (WSC), BC Ministry of Environment, and monitoring agencies around the world. The software acquires, processes, models and publishes environmental data in real time. “When we received Paul’s email we were in the process of launching a new grant program called the Ripple Effect, and KWS's community-based watershed monitoring program was an ideal fit for an inaugural award,” said Kevin Martin of Aquatic Informatics, who was involved in launching the Ripple Effect. A submission was made, KWS was selected as the recipient and they quickly started migrating data over to the Aquarius cloud platform. “Once we began looking at our data in the new program, we were able to see everything in such detail and it was easy to find errors and correct them. It drastically improved the quality of our data as well as our understanding of our hydrometric sites,” said Saso. The software has a portfolio of capabilities for error detection, data cleansing and flagging, automatic bias corrections and rating shift management. These automated procedures eliminate the majority of tedious manual data workup processes. By automating quality assurance and quality control activities, KWS now has greater confidence in sharing this information with researchers, local governments and education partners like Selkirk College. With better data management tools, KWS is now working with Selkirk College to give students from the Integrated Envi- Paul Saso with a Selkirk hydrology student. Credit: Mara Mannaerts ronmental Planning Program valuable field experience. This year, students will be heading out in the field with Saso to conduct salt dilution discharge measurements on a local stream. They have already learned how to measure stream discharge using a flow meter, so they will be comparing data from the two methodologies. “We are always excited to work with volunteers and offer opportunities for local residents and students to gain experience and knowledge about their watersheds, as well as share our expertise in monitoring. Our partnership with Selkirk is a great boost in that regard,” said Saso. Allison Lutz, geography and hydrology instructor at Selkirk College’s School of Environment and Geomatics, said: “Working in partnership with KWS has enabled us to give students hands-on learning in the field with a professional hydrologist using local data, while also building community connections. Understanding hydrological processes and how our hydrological cycle is changing with climate change is important work for any environmental field.” Lutz will be working with Saso to incorporate KWS data into several labs and students will use KWS data to build simple rating curves. In 2020, KWS joined forces with the non-profit Living Lakes Canada (LLC) to support the emerging Columbia Basin Water Monitoring Framework by supplying quality-controlled data to the Columbia Basin Water Hub open-source database. This important new partnership meshed KWS's team with a group ® of environmental professionals at LLC. They run a myriad of cutting-edge science-based water stewardship and assessment ®

continued overleaf…

www.esemag.com @ESEMAG

June 2021 | 47

WATER projects, and in so doing, have created a bridge of knowledge and expertise sharing. “Having our data in Aquarius gave us a new perspective on the enormous amount of historical information we had actually collected and now by sorting and layering data sets on top of each other, we are able to see a richer story behind the numbers,” said Saso. Building rating curves can be a complex task. A single rating for a channel contains ratings, shifts, blends and periods of applicability that describe a channel as it changes over time. The rating tool in the new platform is the gold standard to support the latest global standards set by the U.S. Geological Survey (USGS), International Organization for Standardization (ISO), and the World Meteorological Organization (WMO). It is used by national agencies like the USGS and WSC to efficiently develop accurate and legally defensible rating curves, giving KWS confidence in their flow calculations. Through the web portal, KWS’s valuable data is now instantly available for many different people such as climate change researchers, local governments, engineers, ecologists, local residents, farmers and many more. As more data is accumulated over time, sharing of that information with groups such as WSC, the BC Ministry of Environment, and other research institutes, is expected to result in larger research projects that can help guide conservation efforts, land use planning, development decisions, pro-

Stormwater

tection of water supplies and forest management. It can also provide insight into predicting floods and slides, water supply and impacts of a changing climate. “One of our goals is to build partnerships with new data users so our insights can be used to keep our communities safe and sustainable through research, community planning, and decision making around climate change and water resource needs,” said Saso. The new platform is scalable so KWS can dial up the number of users and type of data collected and manage how this data gets used and by whom. They can make custom dashboards with intuitive maps, alerts and live reports empowering the different stakeholders with useful timely information to make better decisions. All of this is available through the web portal, making it accessible from any connected device. “Thanks to our sponsorship from Aquatic Informatics we now have a tool that ensures we have accurate, accessible, secure data all in one place. It has empowered us to share our valuable understanding of local watersheds with the public, scientists, local governments, and water agencies in order to bring awareness to the health of our watersheds and help us plan and prepare for sustainable and healthy ecosystems and communities into the future,” concluded Saso. Chris Heyer is with Aquatic Informatics. Email: info@aquaticinformatics.com

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48 | June 2021

Environmental Science & Engineering Magazine

WATER TREATMENT

Edmonton engineering firm piloting a novel machine learning water treatment process

SL Adapt (ISL), a sister company to Western Canada’s longstanding ISL Engineering and Land Services Ltd., was created to identify and design artificial intelligence (AI) opportunities that can improve community infrastructure. Working with the University of Alberta’s Reinforcement Learning and Artificial Intelligence Lab (RLAI), the Alberta Machine Intelligence Institute (Amii), and the Town of Drayton Valley, the project will focus on process control, automation and data analytics. “We will demonstrate the possibilities of reinforcement learning in the domain of water treatment processes and industrial control,” says Jason Kopan, ISL Adapt’s lead water infrastructure engineer. “This is the first step in developing AI-driven water treatment systems that can shift the paradigm of water treatment in Alberta and beyond.” “We’re really excited to be working alongside the team at ISL Adapt, both because we get to provide our expertise in reinforcement learning and we get to benefit from their expertise in real systems control,” says Martha White, Amii Fellow and associate professor at the University of Alberta. “Reinforcement learning is a key tool for anyone looking to the future of control processes and industrial automation, and this is an opportunity to demonstrate that as well as solve a real problem right here in our community. Drayton Valley has been a great partner too, and the water treatment plant (WTP) offers an ideal environment for exploring more advanced techniques for water treatment.” This pilot project, believed to be the first of its kind, marks the beginning of exploring AI in everyday infrastructure applications and is funded initially by Alberta Innovates, the National Science and Engineering Research Council of Canada (NSERC), and private investors. ISL believes the next step toward water assurance involves applications of machine learning and AI-driven process control to further support human operators. Recent software and hardware advances in AI have created a rich environment for using reinforcement learning methods on infrastructure assets to optimize drinking water treatment and lower energy costs. Reinforcement learning provides an opportunity to discover proactive insights and optimize complex arrays of operational data in real time that are not necessarily evident given traditional engineering designs, control approaches and limited training opportunities. With these research and innovation platforms, ISL believes its WTP designs will be capable of predicting and responding to water treatment upsets impacted by natural hazards, resource development pressures, and learning more about growing contaminant concerns that affect water quality across Canadian communities.

The Town of Drayton Valley is making its water treatment plant (pictured) available to engineers and researchers from ISL Adapt, the University of Alberta’s Reinforcement Learning and Artificial Intelligence Lab, and the Alberta Machine Intelligence Institute.

Pan-Canadian AI Strategy, Amii (the Alberta Machine Intelligence Institute) is an Alberta-based non-profit institute that supports world-leading research in AI and machine learning and translates scientific advancement into industry adoption. Amii grows AI capacity through advancing leading-edge research, delivering exceptional educational offerings and providing business advice, all with the goal of building in-house AI capabilities. THE DRAYTON VALLEY WATER TREATMENT PLANT The Town of Drayton Valley has taken advantage of a unique opportunity to showcase water management by making available its award-winning water treatment plant. Named the Centre for Water Intelligence, it is a centralized place for pursuing technology advances and allowing the community to visit and learn about what the town does to manage wastewater and stormwater. At this facility, many aspects of water and wastewater treatment technologies and advancements will be explored for the benefit of all Canadians. Town council and administration took steps to incorporate AI into water treatment infrastructure by working alongside ISL Adapt and ISL Engineering to create out-of-the-box solutions. For more information, visit: www.isladapt.com, or www.amii.ca

COLLABORATION PARTNERS One of Canada’s three centres of AI excellence as part of the www.esemag.com @ESEMAG

June 2021 | 49

INDUSTRIAL WATER

Scraper strainers resist clogging and fouling when faced with micron-sized particles By Del Williams

o enable its use as cooling water, industrial facilities pre-filter raw water from rivers, lakes, gulfs and coastlines to remove organic, aquatic and other solids. Cooling water is typically used in a couple of ways. With once-through systems, water circulates through pipes, absorbing system heat before it is returned to its original source. Cooling towers can also utilize water from natural sources. These towers remove heat from machinery, heated process material/fluids, chillers and other sources. Because the cooling water originates from bodies of water, it can be dirty and contain considerable debris, weeds and trash. Strainers are required to remove this waste from the cooling water before it goes into heat exchangers and cooling systems, and to prevent spray nozzles from clogging. Insufficient removal of both large solids and small particulates, such as debris, dirt and other suspended solids, as well as biofouling from organic matter

from the water can create serious problems. Plugging and fouling can cause unscheduled downtime, excessive maintenance, and costly premature replacement. Traditionally, filters are designed to handle either smaller particulates or larger debris, but not both. The challenge is that natural bodies of water are typically rife with both. An automatic scraper strainer from Acme Engineering, a North American manufacturer of industrial self-cleaning strainers, is a motorized unit designed to continually remove both very large and very small suspended solids from cooling water. Cleaning is accomplished by a springloaded blade and brush system, managed by a fully automatic control system. Four scraper brushes rotate at 8 rpm, resulting in a cleaning rate of 32 times per minute. These get into wedge-wire slots and dislodge resistant particulates and solids. This approach enables the scraper strainers to resist clogging and fouling when faced with large solids and

high solids concentrations. It ensures a complete cleaning and is very effective against biofouling. Blowdown occurs only at the end of the intermittent scraping cycle, when a valve is opened for a few seconds to remove solids from the collector area. Liquid loss is well below 1% of total flow. The scraper basket also allows the strainer to bypass extremely large particles and debris. Although industrial facilities with existing systems may be hesitant to replace backwash strainers due to the misperception that the installation modifications can be costly, firms like Acme can custom manufacture pressure vessels to fit within the existing piping arrangement. This minimizes installation costs. They can even deliver units with backwash arms, when needed. Del Williams is a technical writer. For more information, visit www.acmeprod.com

Above: Plugging and fouling from large solids and small particulates can cause unscheduled downtime, excessive maintenance, and costly, premature replacement. Automatic scraper strainers can remove waste from raw water before the debris enters heat exchangers and cooling systems. Right: Pressure vessels can be custom manufactured to fit within the existing piping arrangement, which minimizes scraper strainer installation costs. 50 | June 2021

Environmental Science & Engineering Magazine

AIR QUALITY

Monitoring solvent emissions to ensure compliance

overnments from around the world have implemented environmental regulations to reduce the emissions of volatile organic compounds (VOCs) from industrial processes. VOCs are released from industrial activities that utilize organic chemicals such as solvents, as well as from engines and incinerators that burn organic materials and fuels. Both types of applications require similar monitoring equipment, but this article will focus on those applications that involve solvents. Solvents are used widely in the chemical industry, as well as for cleaning and degreasing products and machinery, or dissolving, thinning and dispersing coatings, adhesives, paints and inks. Solvents evaporate readily at room temperature and represent a significant safety hazard in the workplace, so they are generally vented away from workers. The emissions from such vents frequently require abatement prior to release. Solvent emissions have to be minimized because of their environmental effects, which include the formation of ozone, a constituent of photochemical smog. At ground level, ozone is generated when VOCs react with nitrogen oxides (NOx) in the presence of sunlight. Ozone can have both acute and chronic effects on humans, affecting the respiratory, cardiovascular and central nervous system, as well as reproductive health. Ground level ozone can also have harmful effects on vegetation and sensitive ecosystems.

A Signal MiniFID 3010 analyzer.

lyzer upon receipt of a command from a detachable tablet, or from a remote installation with Signal’s S4i software. This command sets in place a sequence of actions that prepare the analyzer to take samples and report calibrated readings to the instrument’s internal datalogger. Using an optional detachable tablet, users are able to manage the analyzer wirelessly up to 50 metres away. In addition, using the remote S4i software over an Ethernet connection, the analyzer can be operated from anywhere at any time. Remote accessibility also enables alarm monitoring, remote calibration and troubleshooting, if necessary.

installations. The continuous heated FID SOLAR analyzer can be easily fitted into a rack cabinet for indoor or outdoor installa- For more information, visit: tion. It has an embedded microproces- www.signal-group.com sor which automatically starts the ana-

VOC MONITORING The level of monitoring required by regulators is dictated by the scale of an operator’s VOC emissions, with continuous monitoring required for the larger emitters and discontinuous monitoring for processes with lower emissions. Signal Group has developed a portable heated FID (Signal MiniFID 3010) for periodic measurements and a continuous heated FID (SOLAR) for permanent www.esemag.com @ESEMAG

June 2021 | 51

WASTEWATER

Novel aeration system can improve the performance of wastewater treatment lagoons By Jan Korzeniowski

wastewater treatment system designed by J.K. Engineering employs novel aeration technology with a high-efficiency wastewater effluent pump and air aspirator-mixer. Multiple aeration units can be installed, as required, in an aeration pumping station located adjacent to lagoons that need to be upgraded, new ones being built, or concrete tank systems. Wastewater is pumped through the

Two small cells with a total volume of approximately two-day retention capacity can be used. Or, one small cell can be divided into aeration and clarifier cells.

air aspirator-mixer, which aspires air This wastewater treatment system and mixes it with the wastewater. The also uses the activated sludge treatment wastewater and air mixture are then dis- process, which includes wastewater aercharged to the lagoons for treatment, or ation and activated sludge settling and for odour control. recirculation to the aeration system. Two small cells with a total volume of approximately two-day retention capacity can be used. Or, one small cell can be divided into aeration and clarifier cells. Wastewater aeration and activated sludge recirculation to the aeration system, and activated sludge wasting, are done by the aeration pump. The aeration cell and the clarifier cell are provided with perforated PVC piping mounted Quality Service since 2002 at the cells’ bottom on concrete strips In-house Machine Shop or continuous concrete floor, 100-mm Welding and Hard Surfacing thick. There is no equipment in the cells that could break or plug, which would In-house Engineering require draining the cells. In-house 3D Drafting The aerated wastewater can be used to Balancing In-house control odour in anaerobic cells by discharging it into the cells through perService and Repair Se forated horizontal pipe laterals. These Parts Inventory are installed approximately 1.2 metres Field Services below the wastewater operating level and located around the cells such that Preventative Maintenance Program there is a cross flow of aerated wastewater through the cells. PROVIDING EXCEPTIONAL SERVICE The laterals extend into the cells THROUGH INNOVATION, COLLABORATION AND INTEGRITY. between two and three metres and they WWW.SENTRIMAX.COM are spaced between eight and 15 metres apart. They are 75 or 100 mm in diamSENTRIMAX NORTHWEST SENTRIMAX NORTHEAST SENTRIMAX SOUTH EDMONTON, ALBERTA KITCHENER, ONTARIO MANSFIELD, TEXAS eter. Wastewater is withdrawn from the 1-866-247-5141 1-877-741-0118 1-844-327-3632 cells to the aeration system at the oppo-

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52 | June 2021

Environmental Science & Engineering Magazine

The system employs novel aeration technology with a high-efficiency wastewater effluent pump and air aspirator-mixer.

site end from the raw wastewater inlet into the cells, and discharged in the area of the raw wastewater inlet. The aeration system for the odour control is independent from the aeration system for the wastewater treatment. The odour control system provides aeration and biological activity in the anaerobic cells that control odour. Phase 1 of this system is designed for a peak daily flow of 4,500 m3. Phase two is designed for a peak daily flow of 9,000 m3. Two anaerobic cells (A and B) are used for anaerobic treatment. Cell C is used as a clarifier for activated sludge settling and recirculation to the aeration system. Cell D is used for aeration and waste activated sludge is discharged back to anaerobic cells A and B. The aeration system uses four 30-hp high efficiency effluent wastewater pumps. One is used for anaerobic cells A and B. Two are used for cell D and activated sludge recirculation from cell C. One pump is a stand-by to both aeration systems. This treatment system can be designed to secondary treatment level for control of TSS and CBOD or to tertiary treatment level with nutrient control in a biological nutrient removal (BNR) system. Aeration provided by the air aspirator-mixer and wastewater recirculation pump provides high efficiency oxygen transfer to wastewater. This is because the wastewater and air contact begin at the air aspirator-mixer and continues in the downstream piping and in the aeration cell. The oxygen transfer can be over 50%. Air blowers and diffusers are not used. Incoming air for the air aspirator-mixer may contain dust, moisture, odour, high or low temperature without a negative effect on the aeration system. A uniform supply of aerated wastewater throughout the aeration cell is provided by engineered perforated PVC pipes that have small holes for air discharge at the top, and larger holes at the bottom for wastewater discharge. To eliminate the need for sludge scrapers, the secondary clarifier cell is provided with engineered PVC pipes perforated at the bottom for uniform collection of activated sludge throughout the cell. The wastewater recirculation pump aerates wastewater in the aeration cell, returns activated sludge from the secondary clarifier to the aeration cell and wastes excess activated sludge www.esemag.com @ESEMAG

to the sludge holding cell. Plugging with suspended solids or dust is not an issue, which eliminates the need for system shutdown, repairs or replacement. Overall installation and operating costs are 30% to 40% lower than those of conventional treatment systems. Jan Korzeniowski is with J.K. Engineering Ltd. Email: jkeng@telus.net

June 2021 | 53

INFRASTRUCTURE

Dealing with the challenges of cleaning municipal sewer and stormwater lines

perators cleaning municipal sewer and stormwater lines face a host of challenges. This can range from having to clean kilometres of line in the most efficient manner, and complying with annual regulatory mandates, to handling tough blockages caused by roots, grease and cave-ins. “Most of the problems are in 100 to 450-mm diameter sewer pipe, which accounts for up to 95% of all the pipe in the ground,” says Dan Story, KEG Technologies operations manager. “Proper training and education can resolve the majority of these issues.”

According to Story, a Tier-1, 30-degree drilled nozzle running 275 litres per minute at 2,200 psi will only exert 13 pounds of force to move debris three metres away from the nozzle. In contrast, a very high-efficiency Tier-3 nozzle running 230 litres per minute at 2,000 psi will impact that plate three metres away with 98 pounds of force. “If your objective is to remove debris out of the sewer line, which one’s going to do it better? 98 pounds of force or 13 pounds of force?” asks Story. “Using high-efficiency Tier-3 nozzles are key to getting more done in less time.”

TO CLEAN FASTER, SLOW DOWN The number one mistake of most operators is simply rushing through the cleaning process. “Most operators run their cleaning nozzles way too fast. Learning sewer cleaning best-practice Slow the nozzle down and let it do its job. techniques usually pays off quickly. You’re not in a race. If you run the nozzle up in a hurry and back in a hurry, all you do is waste water and time,” says Story. According to Story, when operators CHOOSE THE RIGHT slow down and let the water flow carry NOZZLE FOR THE JOB the material back to the evacuation In addition to going slow, Story point, the water in the pipe becomes a emphasizes that choosing the right noz“conveyor belt that moves the material.” zle for the job is critical. “By going slow “If you clean correctly, the water is and using the right type of nozzle, you going to carry the debris off and out of will clean your line in one pass,” he says. the way,” says Story. “That is why with Story points out that in many cases, 150 to 375-mm diameter lines, 95% of the using a high efficiency Tier-3 nozzle will time it is possible to go from manhole to provide significantly more cleaning force, manhole and clean them in one pass.” at a greater distance, with less water. This “As you go into the pipe, if you go in enables crews to get more line cleaned slow enough, you should be running before having to leave the job site to refill between 12 and 18 metres per minute, the sewer truck with water. based on the condition of the pipe and There are tiers of nozzles, rated for how much material is in the pipe. The water efficiency from Tier 1 (about 30% more material, the slower you want to efficient), Tier 2 (50% to 60% efficient), move,” he says. to Tier 3 (75% to 98% efficient). “You want to be able to chop that However, even within the Tier 3 catematerial up and get it in the flow of the gory, there are significant differences in pipe’s stream. When you get to the end levels of efficiency. Opting for the lowof the line, dial your pressure back down er-end Tier 3 nozzle with 75% efficiency and rinse it. When you come back, the could still lead to additional trips to refill. job is done,” he adds. Additionally, such units may not remove restrictive sewer buildup or blockage in a timely manner.

SLOW DOWN EVEN MORE TO REMOVE BLOCKAGES With blockages including roots, grease, mineral deposits and caveins, it is essential to clean even slower when encountering one. “If the operator rushes up the sewer line, sooner or later they will run into a blockage of roots, grease, etc., and plug up their front jets. Now, they no longer have a penetrating tool. They have a battering ram, a nozzle with no forward jets trying to feed its way through the blockage,” says Story. “Instead, slow down even more to remove a blockage and let the nozzle do the work. The reason we put forward jets on those nozzles is so they can open the blockage before the nozzle arrives. By slowing it down, the water will open the blockage even before the nozzle ever gets there,” he advises.

54 | June 2021

AVOID BLOWN TOILETS A “blown toilet” can leave sewer material on a homeowner’s floor and toilet seat causing public relations issues. This occurs when an operator rushes up the sewer line with little or no cleaning going up the sewer line on the first pass. This results in excessive piles of debris on the return trip through the same stretch of sewer line. According to Ken Billingham, KEG international product specialist, air flow from the jet nozzle compresses between

Environmental Science & Engineering Magazine

the nozzle and the debris, creating significant positive pressure. When the debris passes by a home’s service line, the pressurized air blasts up and out of the service line, causing a blown toilet. The solution, according to Billingham, is to slow down and clean going down the sewer line and back. This can largely prevent the conditions that too often lead to blown toilets. The same approach can prevent rotting black material trapped in sewer pipe sags getting launched into home- A KEG Kleen-Sight camera nozzle. owner’s bathrooms. “By cleaning slowly, operators are able to pull the water and trapped material out of the pipe sags, so they will not blow the worst kind of material out of the toilet,” says Billingham. When the City of Ottawa, Ontario had a serious issue with blown toilets, the city council would not allow sewer cleaning crews to go into certain parts of town where there were chronic problems. After Billingham conducted a A KEG Supernova 4000 chain cutter nozzle. three-day training session with the city’s operators, the local newspaper reported that the training had helped to reduce blown toilets in the city by 88%. know when it’s in contact with roots. You can feel it. You can smell it. You can SET UP AND USE CHAIN hear the change in the way that the tool CUTTERS CORRECTLY works. Just keep feeding it in slow and Chain cutters can be used to remove steady until it gets through the problem.” most types of sewer line blockages. As an example, high output torque cut- USE A CAMERA NOZZLE TO QUICKLY ters such as KEG’s micro chain cutter DETERMINE THE PROBLEM can readily remove light roots, while its OR VERIFY COMPLIANCE Supernova chain cutter is designed to When municipalities need to quickly eliminate heavy root blockages as well assess the condition of a sewer line to as scale, mineral deposits, and years of determine a solution or document its hardened grease. condition to verify mandated compliHowever, these tools must be set up ance, nozzles with integrated cameras and used correctly. “Chain cutters are can accomplish both during routine forgiving, but most people are hesi- cleaning. tant to use them because if they are set “A small municipality could use a camup wrong or run improperly, they can era-nozzle to inspect their own pipes to destroy the pipe. If you set it up right, verify they are clean instead of contractand run it properly, you will never dam- ing it out. If they found any major probage a pipe,” says Story. lems, they could bring their contractor Story says that operators must first in,” says Billingham. “When the operator set up cutters correctly and follow the is having problems trying to get through manufacturer’s guidelines. In general, a pipe, a camera-nozzle can take a quick he advises, it is best to set up the cutter look at it, so they can pick the right tool, chain to be about 25 mm smaller than whether it is a cutter, blockage nozzle, or the pipe it will cut. digging crew,” he adds. As for operating the cutter, he says: For example, KEG’s KleenSight cam“Let the tool find its way down. You will era-nozzle offers operators the ability www.esemag.com @ESEMAG

to clean sewer and storm lines while recording video, as well as to quickly assess the line without having to use a CCTV camera truck. Only a jetter hose connection is required – no cables or wires. With Wi-Fi capability, the camera captures video in memory and allows viewing and downloads on any Wi-Fi enabled device, such as a smartphone, laptop, etc. Story adds an important word of caution: “Anytime you put a root cutter in any kind of pipe, the line should always be inspected first with a camera, and a camera nozzle makes this easy. Also, all cutting should be done with a camera to help the operator know what they are doing. This is critical because if you’re not inspecting the pipe, you’re liable to hit electric lines, gas lines, or fibre optic lines. This can cause explosions or serious outages.” CONDUCT INDUSTRY BESTPRACTICE TRAINING TO OPTIMIZE SAFETY AND PRODUCTION Most municipal operators and contractors do not have the time to keep up to date with the industry’s best practices and equipment. That can lead to costly errors and even safety hazards. For those who want to enhance the safety and productivity of their workforce, scheduling periodic or ongoing training can resolve serious issues and turn problems into strengths, as training did with the City of Ottawa. “Whether operators take advantage of online or in-person classes, or get hands-on instruction, guidance and practice right in their own communities, learning best-practice techniques usually pays off quickly in improved service quality and production,” concludes Story. KEG Technologies’ Canadian office is based in Abbottsford, B.C. For more information, email: kbillingham@kegtechnologies.net, or visit: www.kegtechnologies.net

June 2021 | 55

PRODUCT & SERVICE SHOWCASE

STORMWATER MANAGEMENT

The new Ecobloc SMART series of stormwater infiltration modules replaces Maxx & Inspect Flex with superior performance (96% efficiency). It offers ultra-deep installation, up to 7.5m burial; vehicle loading up to 60t (HS-25 loading); enhanced access for cleanout/ inspection – every row is inspectable; and, improved logistics (up to 10 – 15% more blocks per container). Can handle heavy loads, such as crane operation areas, and special applications, such as container terminals, heavy machine operating yards, etc. BARR Plastics T: 800-665-4499 E: info@barrplastics.com W: www.barrplastics.com

MULTI-DIAPHRAGM DOSING PUMP

The CHEM-FEED® Multi-Diaphragm MD1 Chemical Dosing Pump is engineered to deliver smooth and continuous chemical feed in municipal water and wastewater treatment applications. The MD1 will not lose prime, making it ideal for pumping chemicals that off-gas. MD1 requires minimal maintenance and the patented DiaFlex® diaphragm is built to last the life of the pump. Blue-White Industries T: 714-893-8529 F: 714-894-9492 E: info@blue-white.com W: www.blue-white.com

TUBE REPLACEMENT MADE SIMPLE

The NEW Modular Roller Assemblies for FLEXFLO® M4 Peristaltic Dosing Pumps are shipping now. This enhanced design allows for safer, easier tube replacement and there’s no special tube installation tool required. Each roller can be replaced individually so there is no need to purchase the entire roller assembly. Users can switch to different tube assemblies without changing the roller assembly. Blue-White Industries T: 714-893-8529 F: 714-894-9492 E: info@blue-white.com W: www.blue-white.com 56 | June 2021

TWIN SHAFT GRINDER

Eliminate downtime with the Boerger Multicrusher – a twin shaft grinder for processing debris including wood, wet wipes, plastics, textiles, etc. Do you have confined space conditions? The vertically installed Multicrusher is a great space-saving option! Quick access to parts with the back-pull-out design. Boerger T: 612-435-7300 E: america@boerger.com W: www.boerger.com

PIPING SYSTEMS FOR SODIUM HYPOCHLORITE

Chemline’s ECTFE is our proven, longterm rigid piping system solution for sodium hypochlorite applications in sewage and water treatment plants. ECTFE withstands oxidizing chemicals where other plastics fail. We offer single wall and dual containment systems, fusion machines and TSSA approved training, resulting in leak-free service and long-term value. Chemline Plastics T: 800-930-CHEM (2436) F: 905-889-8553 E: request@chemline.com W: www.chemline.com

BLOCK WATER FROM ACCESSING ASSETS

Road erosion, premature concrete failure or water ingress into wastewater systems? Denso’s 12 "LT tape has been proven for nearly a century to block water from accessing assets. It won’t harden or crack and is the perfect solution to protect concrete and prevent I&I. Applied in minutes, requiring minimal surface preparation, no mixing or curing, it can be buried immediately. Denso North America T: 416-291-3435 E: sales@densona-ca.com W: www.densona.com

Environmental Science & Engineering Magazine

PRODUCT & SERVICE SHOWCASE

ENVIRONMENTAL DUE DILIGENCE ON-SITE

Your on-site visits just got easier and more efficient with our new game-changing field app. Access your ERIS projects and data; see map layers, add notes, capture photos, complete checklists; then upload and access your files. ERIS Mobile facilitates exceptional property risk assessments–on the go. Do more in the field. Save time in the office. ERIS – Environmental Risk Information Services T: 416-510-5243 E: bford@erisinfo.com W: erisinfo.com

PIPE AND PRECAST PRODUCTS

Forterra is a leading manufacturer of pipe and precast products. Our products improve quality of life, provide sustainable infrastructure and help communities grow and thrive. A specialized technical sales force, including engineers and field representatives, delivers a high degree of customer service and tailored solutions. Forterra delivers industry-leading service, quality, innovation and commitment. Our mission is to build the longest lasting infrastructure for our communities’ today and tomorrow. Forterra T: 519-622-7574 F: 519-621-8233 E: canada@forterrabp.com W: www.forterrabp.com

CHLORINE EMERGENCY SHUTOFF

The Gemini™ Emergency Shutoff System adds a new level of safety to your gas chlorine feed system. Designed specifically for dual 150 lb chlorine cylinder applications, the Gemini System, with its two Terminator™ actuators, stops a chlorine leak within seconds of detection by automatically closing the cylinder valves. The actuators are simply placed on top of the valves and protection begins. Halogen Valve Systems T: 949-261-5030 W: www.halogenvalve.com

MONITOR CHEMICAL USAGE, CONTAIN SPILLS

The SpillSafe LX™ Drum Scale from Force Flow accurately monitors amount of chemical used and remaining, and provides protection against uncontained chemical spills. An automatic deploying spill bladder keeps overall platform height to a minimum for easy drum change-out, while still allowing up to 250 litres of spill containment. The SpillSafe LX helps you comply with Environmental Canada spill containment requirements. Force Flow T: 925-686-6700 E: info@forceflow.com W: www.forceflowscales.com

www.esemag.com @ESEMAG

LAKE CIRCULATORS

SolarBee© Active Lake Circulators help control cyanobacteria (blue-green algae) in lakes, reservoirs and ponds. Whether you manage a raw water drinking source or a recreational or stormwater pond, a key component for cyanobacteria (blue-green algae) control is to circulate the epilimnion, the upper layer of water. One solar powered circulator can treat up to 35 acres. Greatario T: 866-299-3009 E: info@greatario.com W: www.greatario.com/greatwater

CATCH BASIN INSERT

The LittaTrap Catch Basin Insert is a low-cost, innovative technology that prevents plastic and trash from reaching our waterways. Designed to be easily retrofitted into new and existing stormwater drains, the LittaTrap is installed inside storm drains and when it rains, catches plastic and trash before it can reach our streams, rivers and oceans. Imbrium Systems T: 800-565-4801 E: info@imbriumsystems.com W: www.imbriumsystems.com

June 2021 | 57

PRODUCT & SERVICE SHOWCASE

SERVICE-IN-PLACE PUMP

OGS/HYDRODYNAMIC SEPARATOR

The new Stormceptor® EF is an oil grit separator (OGS)/hydrodynamic separator that effectively targets sediment (TSS), free oils, gross pollutants and other pollutants that attach to particles, such as nutrients and metals. The Stormceptor EF has been verified through the ISO 14034 Environmental Management – Environmental Technology Verification (ETV). Imbrium Systems T: 800-565-4801 E: info@imbriumsystems.com W: www.imbriumsystems.com

NETZSCH’s maintenance-friendly Full Service-in-Place (FSIP®) NEMO® progressive cavity pump has a large inspection cover. Open the pump cavity on-site, dismantle all rotating parts and replace them without removing the pump from the pipe assembly. Capacities and pressures are equal to the same size classic NEMO progressing cavity pump – known for continuous, pressure-stable, gentle and low-pulsation conveyance of almost any substance. NETZSCH Canada T: 705-797-8426 F: 705-797-8427 E: ntc@netzsch.com W: www.netzsch.com

WATERTIGHT DOORS

METAL CUTTERS FOR HARSH ENVIRONMENTS

Wastewater is tough on grinders. Gritty material wears the cutters and acidic conditions corrode them. Previously, operators had to choose hard steel alloy cutters and sacrifice corrosion resistance or choose softer corrosion-resistant stainless steel cutters and sacrifice abrasion resistance. Now you can have both with JWC Monster Metal. JWC Environmental T: 800-331-2277 E: jwce@jwce.com W: www.jwce.com

58 | June 2021

Huber, a proven German manufacturer, now provides watertight doors that allow safe access to tanks for construction and/ or maintenance. Doors can be provided as round or rectangular for installation onto existing concrete surfaces or cast-inplace in new concrete. They can handle heads up to 30 m and hold pressure in seating and unseating directions. Huber’s watertight doors can greatly reduce construction and maintenance costs and dramatically improve safety/access. Pro Aqua T: 647-923-8244 E: aron@proaquasales.com W: www.proaquasales.com

HYPERBOLOID MIXERS

Invent Environment is the manufacturer of hyperboloid mixers which have revolutionized anoxic and swing zone mixing. Invent provides low-shear, efficient mixers with no submerged motors or gear boxes for easy access for maintenance. They have now released the Hyperclassic Mixer Evo 7 which has increased the number of motion fins and adjusted the geometry of the mixer to maximize mixer efficiency, reducing operation costs even further. Pro Aqua T: 647-923-8244 E: aron@proaquasales.com W: www.proaquasales.com

CONTROLLING CONTAMINATED GROUNDWATER

Waterloo Barrier is a low permeability cutoff wall for groundwater containment and control. It is a new design of steel sheet piling, featuring joints that can be sealed after the sheets have been driven into the ground, and was developed by researchers at the University of Waterloo. It has patent/patent pending status in several countries. Canadian Metal Rolling Mills assisted in developing the product. Waterloo Barrier T: 519-856-1352 F: 519-856-0759 E: info@waterloo-barrier.com W: www.waterloo-barrier.com Environmental Science & Engineering Magazine

ES&E NEWS SASKATOON WASTEWATER SURVEILLANCE PARTNERSHIP RECOGNIZED

ton, South Carolina’s public works comThe settlement is being seen as a missioners, vowing to improve the benchmark for an industry that has a “flushability” of its Cottonelle Flushable number of outstanding legal actions Wipes, and improve its package labelling. against wipe manufacturers. The typical The Charleston Water System’s lawsuit argument in these cases is that “flushable” alleged that packaged wipes were dubi- wipes do not disintegrate as effectively ously labelled “flushable” and instead as toilet paper and can wrap or “rope” “wreaked havoc” by clogging local sewer around other wipes and debris to cause systems. continued overleaf…

Delivering clean water solutions for 60 years

City of Saskatoon WWTP Manager Mike Sadowski (right), with USask Toxicologist Markus Brinkmann holding a wastewater sampling device. Credit: David Stobbe

Saskatoon’s wastewater surveillance practices for COVID-19 and marine pollution have placed it on a list of 50 international projects named to the 2021 Smart 50. The list recognizes the 50 best examples of smart cities at work each year by highlighting specific projects with “real municipal-scale” results. The Smart Cities Connect Media and Research organizers recognized the collaboration between the University of Saskatchewan (USask) the City of Saskatoon, and the Saskatchewan Health Authority, to facilitate testing of the viral signal in the wastewater and determine increases in new positive cases seven to 10 days after sample collection. They also recognize the collaborative research team’s ability to measure levels of human pharmaceuticals such as antibiotics in Saskatoon’s wastewater, to assess potential risks these chemicals might pose to the downstream environment. The USask research team was given $137,392 from the Public Health Agency of Canada to conduct a six-month COVID-19 wastewater surveillance project in Saskatoon and at five Saskatchewan First Nations communities, to provide early warning of outbreaks. Results from the work will be used for pandemic modelling and to inform public health decision making and health care capacity planning, using a combination of artificial intelligence and computer simulation.

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LANDMARK SETTLEMENT OVER WIPES

Wipes manufacturer Kimberly-Clark Corp. has settled a lawsuit with Charleswww.esemag.com @ESEMAG

June 2021 | 59

ES&E NEWS clogs, “fatbergs” and other treatment problems, “making them costly and difficult to manually remove,” the Charleston Water System lawsuit alleged. Under the Kimberly-Clark Corp. settlement, the Scott toilet paper manufacturer agreed to make Cottonelle wipes meet the wastewater industry’s flushability standards by May 2022.

REMOVING MICROPLASTICS FROM LAKE ONTARIO

A Seabin is photographed at the launch of Phase Two of the program. Credit: CNW Group/PortsToronto

A pilot project and collaboration between PortsToronto and the University of Toronto collected about 85,000 small pieces of anthropogenic debris from Lake Ontario in just over a four-month period in 2020, with the use of floating litter-capturing Seabins technology. Through the use of three Seabins, which are essentially floating garbage cans that suck up litter as it floats by, the team primarily captured hard plastic fragments, plastic film, and pre-production plastic pellets. Specifically, bottle caps, cigarette butts, plastic straws and bags were the most common waste collected from the lake. “We discovered that floating algae and plant material, common in shallow and sheltered marinas, collect and accumulate small anthropogenic litter,” the PortsToronto team says in its research. “Acting as a natural mesh, algae and plant material help capture the smaller size fraction of plastic litter.” Seabins were invented in 2014 by Australian surfers who were concerned by the amount of plastic pollution in the ocean. They work by moving up and

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60 | June 2021

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down with the natural flow of water, collecting all floating debris. Water is sucked in from the surface with a submersible water pump and passes through a catch bag inside the Seabin. The water is then pumped back into the harbour, leaving litter and debris trapped in the catch bag to be disposed of properly.

NEW STORMWATER MODELLING TOOL FROM WRF

A new online screening tool allows municipalities to make planning decisions for green and grey stormwater infrastructure management scenarios through a life cycle cost framework and other modelling. Released by the Water Research Foundation, the free community-enabled life cycle analysis of stormwater infrastructure costs (CLASIC) tool can accommodate regional and scale variations to support integrated planning at a municipal scale. Users can create scenarios of stormwater control measures, including climate and land use projections to assess life cycle costs, performance, and co-benefits associated with those scenarios, but its creators say the tool is not intended for the optimization of design. The cloud-based CLASIC tool is fully interfaced with GIS and links with national databases. Users have the option to automatically upload data from national databases (e.g., census, national land cover database, PRISM climate database, digital elevation models, etc.) or to upload their own data sets. Users can select from a mixture of green and grey stormwater practices, like rain gardens, infiltration trenches, permeable pavement, green roofs, storage vaults, wet ponds and stormwater harvesting. The tool then allows users to build and compare multiple stormwater infrastructure options and enables simulation of various climate scenarios. The CLASIC outputs are displayed in a set of charts, graphs and tables that can be analyzed and printed. With stricter stormwater ordinances to reduce peak flows off-site, many municipalities are faced with financial restrictions when making new infrastructure plans. The tool also allows users to prioritize specific social, environmental and economic co-benefits, such as building

Environmental Science & Engineering Magazine

ES&E NEWS energy efficiency, mental health impacts, or groundwater flow increase. Users can also set targets for variables like pollutant reduction, runoff reduction, or cost.

metres or more. The theory was that it would be better to have a reporting system for releasing effluent that could be supported by proper monitoring and record keeping. The regulations also imposed deadNEW BILL AIMS TO REVERT lines on municipalities for building FISHERIES ACT and upgrading their systems to meet Canada’s Wastewater Systems Efflu- the standards of secondary wastewater ent Regulations (WSER) were intro- treatment. duced in 2012 to manage wastewater Bill C-269, introduced by former releases by systems that collect an aver- Conservative Leader Andrew Scheer, age daily influent volume of 100 cubic proposes to revert the Fisheries Act to its pre-2012 status, when companies and communities could be charged for dumping sewage, essentially redefining raw sewage as what is called, under the Act, a deleterious substance. If the

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bill were to receive royal assent, municipalities would have five years to upgrade their wastewater systems. But critics of the bill say that it would only penalize communities already struggling to make real progress on wastewater treatment. To once again charge municipalities for dumping raw sewage would in no way help them to secure the necessary funding for wastewater infrastructure upgrades, said Bloc MP Monique Pauzé. In 2016, the Federation of Canadian Municipalities estimated that at least $18 billion would be needed to upgrade municipal wastewater systems to comply with federal standards, but the federal government has pledged significantly less.

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June 2021 | 61

INTERNATIONAL WATER

A simple approach to improve the quality of rice paddy processing wastewater By C. Neshankine and Dr. N.Kannan

n Sri Lanka, there are 70,000 rice mills performing parboiling of 2.8 million metric tonnes of paddy (rough rice) per year. Rice processing is the country’s largest agro-based sector, producing more output per unit of product than any other industy. In the rice industry, two kinds of products, raw rice and parboiled rice, are produced for consumers. Parboiling is an energy and labour-intensive pre-milling process. Parboiling aims to improve the quality and yield of the rice (head rice). More than 67% of the world’s population consume parboiled rice. Milling of paddy without any pre-treatment is highly susceptible to breakage and loss of minerals and vitamins. The rice mill industry in Sri Lanka uses different types of soaking such as cold, hot, and vacuum soaking. However, most of the milling industry uses the cold soaking process, which takes 48 – 72 hours for the paddy to reach 30% moisture content. The duration is dependent on paddy variety and environmental factors. Wastewater coming from rice mill operations contains high concentrations of organic and inorganic substances, causing significant pollution. The volume of wastewater generated is 0.4 to 0.52 L per kg of paddy processed. In Sri Lanka, many rice industries discharge effluent without any treatment directly into the environment. The release of wastewater to surface water can affect the fertility of fish, another important food source. Moreover, soil respiration and enzyme activities can be inhibited by about 25% – 34%. Research shows such wastewaters have a low concentration of dissolved oxygen (DO) – 0.9 mg/L, a moderate concentrations of chemical oxygen demand (COD) – 630 mg/L, chloride (140 mg/L), total dissolved solids (TDS) – 670 mg/L. Total suspended solids (TSS) – 530 mg/L, and biological oxygen demand (BOD) – 459 mg/L) were much higher than the recommended standards set by the Sri Lanka Standards Institution (SLS) for the discharge of effluent into inland surface waters.

Line diagrams of different soaking systems.

system, water is circulated through submerged paddy grain. A pump draws water, which then gets sprinkled through overhead shower heads to increase DO diffusion. An exposed aerated soaking system can lead to germination of paddy grain, due to a higher amount of DO concentation which induces metabolic activity within the grain. This is not good for milling yield, as grains tend to germinate more quickly. In summary, a submerged aerated soaking system is more effective than other conventional, or exposed aerated soaking systems. It will help maintain the positive dissolved oxygen (aerobic) concentration in the soaking water and increase the hydration rate of the paddy. Furthermore, it reduces the time taken for the soaking process and reduces the chemical and biological oxygen demand of the effluent and significantly reduces effluent volume. Hence, it is viable and a novel option for a better parboiling process.

MODIFIED AERATED SOAKING SYSTEM C. Neshankine and Dr. N.Kannan are with the University A modified aerated soaking system can help improve efflu- of Jaffna in Sri Lanka. For more information, email: ent quality, as it maintains a positive DO value through water nkannan@univ.jfn.ac.lk circulation and the addition of oxygen. Moreover, this activity prevents anaerobic fermentation of organic matter, reduces the BOD value of the wastewater, minimizes microbial colonies in the effluent, and reduces odour development. In a conventional soaking system, the use of stagnant water is common. With aerated soaking systems, water is circulated through the paddy column. In a submerged aerated soaking 62 | June 2021

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