Perfluoroalkyl and Polyfluoroalkyl Substances: A New Incentive for Potable Reuse?

from Florida Water Resources Journal - April 2023

Trenching: Don’t Dig Into Trouble!

Viraj deSilva and Justas Rutkauskas

Florida’s rapid growth has alarmed water utility authorities because increased demand for potable water is quickly depleting the Sunshine State’s natural aquifer system. The population of Florida has increased by approximately 3.4 million people over the last 12 years, stretching the state’s finite freshwater resources (Census, 2023). Meanwhile, Florida, like the rest of the United States, is increasingly monitoring water resources for per- and polyfluoroalkyl substances (PFAS) due to their widespread detection and adverse health effects (Florida Department of Environmental Protection [FDEP], 2022). The confluence of these two trends creates opportunities to rethink traditional water supplies and expand on new ones.

Both federal and state regulatory landscapes continue to evolve. The U.S. Environmental Protection Agency (EPA) has established PFAS health advisories and is developing new regulations and maximum contaminant levels (MCLs) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Also, states such as California have established strict concentration levels, requiring a response by water suppliers. Simultaneously, drought-prone states seeking alternative water supplies increasingly see potable reuse as an option. Several states have already established regulations for indirect potable reuse (IPR), while others are developing frameworks for both IPR and direct potable reuse (DPR) to incentivize municipalities to add potable reuse as a resource.

Florida has implemented the use of reclaimed water for nonpotable uses, but has no utility-scale operational IPR or DPR facilities. Nonetheless, multiple utilities across the state have started potable reuse pilot studies to demonstrate innovative advanced treatment methods using this alternative water source. The advanced water treatment technologies used in potable reuse facilities, primarily reverse osmosis (RO) and granular activated carbon (GAC), are two of the three currently commercially available technologies that have shown high removal efficiencies of PFAS compounds. These pilot studies, along with results from other states, can help Florida tap further into the promise of potable reuse.

Viraj deSilva, Ph.D., P.E., BCEE, is chair of the Water Environment Federation PFAS Task Force. He is senior treatment process leader, and Justas Rutkauskas is an engineer, with Freese and Nichols Inc. in Tampa and Austin, Texas.

Federal Perfluoroalkyl and Polyfluoroalkyl Substances Guidance

The EPA has taken the initial steps of regulating PFAS compounds due to the increasing rates of detection across the U.S. The agency established a health advisory limit of 70 ng/L in drinking water for the sum of PFOA and PFOS in 2016 (EPA, 2016), and that was superseded in June 2022 by 0.004 ng/L for PFOA, 0.02 ng/L for PFOS, 10 ng/L for GenX chemicals, and 2,000 ng/L for perfluorobutanesulfonic acid (PFBS) (EPA, 2022).

The PFAS Strategic Roadmap, released in October 2021, summarized actions that EPA plans to take through 2024 in a multifaceted approach to mitigate the widely spread PFAS contamination of water and land throughout the U.S.

A draft of national primary drinking water regulations for PFOA and PFOS is planned to be released in April 2023, with the final regulation projected to be finalized before the end of 2024. A related regulation, the proposed Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), requires all public water systems serving 3,300 or more people to collect samples that will be tested for 29 PFAS chemicals from January 2023 through December 2025 (EPA, 2021).

Most states are following EPA’s current health advisory limits, but aren’t taking additional action before federal regulations are adopted. A few states, however, are moving faster, with stricter health advisories and regulations for PFOA, PFOS, and added additional PFAS chemicals. Notably, California has set response levels of 10 ng/L for PFOA, 40 ng/L for PFOS, 5000 ng/L for PFBS, and 20 ng/L for perfluorohexane sulfonic acid (PFHxS). Under state law, a community water system must take the water source out of use or provide public notice within 30 days of the listed PFAS chemical detection if the constituent concentrations exceed the response levels (State Water Resources Control Board [SWRCB], 2023).

In January 2023, Pennsylvania approved 14 ng/L PFOA and 18 ng/L PFOS limits, requiring water companies and municipalities to treat the water if these limits are exceeded.

Florida Potable Reuse Guidelines

Strict wastewater treatment plant (WWTP) outfall restrictions were established in Florida by Senate Bill 64, which requires all domestic wastewater utilities to eliminate nonbeneficial effluent discharge into surface water bodies by 2032. Utilities that did not meet the November 2021 deadline to provide a plan for eliminating effluent discharges will have to meet the requirements by 2028. The bill provides an incentive for potable reuse project development, as it specifies potable reuse as an alternative water supply (provides potable reuse project eligibility for alternative water supply funding) and considers treated WWTP effluent discharges associated with IPR projects as beneficial discharge (Florida Senate, 2021).

The FDEP is currently undergoing a potable reuse rulemaking effort to address both DPR and IPR within state regulations. The proposed framework indicates that treated reused water must meet all drinking water standards and be treated for contaminants of emerging concern (FDEP, 2021).

Currently, the Florida Administrative Code defines surface water augmentation, a form of IPR, as the approved planned potable use of recycled water. A summary of potable reuse requirements is provided in Table 1.

Award-Winning Direct Potable Reuse Pilot Project in Florida

The City of Altamonte Springs, serving 45,000 residents, has been successfully operating a DPR demonstration pilot, called pureALTA, since 2017. The project is exploring DPR as a more-sustainable alternative than IPR due to reduced costs of additional stages of pumping and treatment, providing data to FDEP for future DPR regulatory framework development, and demonstrating a potable reuse technology alternative that does not produce a concentrate discharge like RO-based facilities (Martz et al., 2019). The facility won the 2017 WateReuse Innovative Project of the Year award and was ranked in the top three at the International Water Association Project Innovation Awards (Altamonte Springs, 2017; 2018).

The 28,000-gal-per-day (gpd) pilot facility takes treated tertiary effluent before the chlorination stage from the Altamonte Springs Regional Water Reclamation Facility, treats it in a GAC-based treatment train, and returns it to the city’s reclaimed water system to be used

Process Design Parameters

Ozonation

Biological Activated Carbon

Ultrafiltration

Granular Activated Carbon

Ultraviolet Light

Contact time = 3 min

Hydraulic loading = 2.9 gpm/ft2

Empty bed contact time (EBCT) = 15 min

Surface area = 775 ft2

Pore size = 0.01 μm

Media size = 0.8-1 mm

EBCT = 14.3 min at 17 gpm

UV dose = 900 mJ/cm2 for irrigation during the study phase of the pilot (Altamonte Springs, 2017). The pureALTA pilot consists of ozonation and biological activated carbon {BAC) filtration, followed by ultrafiltration (UF) membranes, GAC, and an advanced oxidation process (AOP) that involves hydrogen peroxide injection and ultraviolet (UV) light, as shown in Figure 2. Design parameters of different processes are outlined in Table 2 (Kumar et al., 2021).

A year-long study was conducted to test PFAS and their precursors in the pureALTA facility influent at different stages of the treatment processes and the effluent. The study showed that the GAC treatment step contributed to the largest removal percentage of various PFAS constituents, with the GAC bed change-out becoming the controlling parameter of the treatment train. The PFOS and PFOA have been removed to levels below the measuring limits, with up to 10,000 bed volumes (BV), while short-chain PFAS reached complete breakthrough at approximately 2,000 BVs. The influent concentrations and measuring limits of PFOS and PFOA are provided in Table 3 (Kumar et al., 2021).

Florida IPR requirements indicate a 3-mg/L TOC limit, which was determined to be the controlling factor of the bed change-out in this pilot, as the PFOS and PFOA feed concentrations were below EPA’s 70-ng/L total or individual

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Continued from page 11 constituent health advisory limit (superseded in 2022) that was used as the basis for PFAS removal in this study (Kumar et al., 2021). Potentially lower PFOA and PFOS concentration limits in the future, or short-chain PFAS regulations, could drive the GAC change-out requirements.

Successful Pure Water San Diego Demonstration

The City of San Diego has started implementing its Pure Water San Diego program, which will provide one-third of the public water supply by 2035 (San Diego, 2016). In addition to numerous improvements to the water distribution system, the North City Water Reclamation Plant (NCWRP) will be expanded and the North City Pure Water Facility (NCPWF) will be constructed (San Diego, 2019). With the allocation of $1.5 billion to complete the entire system, the city aims to produce 30 mil gal per day (mgd) by 2025 (San Diego, 2021).

The reclamation facility will pump treated effluent to the NCPWF. The water will then be treated through a multistep train that begins with ozonation, then flows through both BAC and low-pressure and RO membranes. The treatment process is finished with UV/advanced oxidation. The purified product will be pumped to the Miramar Reservoir for additional environmental filtration. With construction underway, the NCPWF serves as the first IPR project in California to augment the reservoir, and completion is anticipated for 2025 (San Diego, 2019).

In an effort to involve the public in the Pure Water program, the city began operation of a 1-mgd demonstration facility in 2011. The facility successfully treats tertiary effluent from the NCWRP with a train consisting of microfiltration (MF) and RO filtration and UV/ AOP. Both the tertiary effluent and demonstration facility product were monitored for one year; during this time, samples were taken on four occasions to test for six PFAS compounds, and only perfluoroheptanoic acid (PFHpA) and PFOA were detected. All four sampling events encountered PFOA concentrations exceeding the existing California PFOA notification level of 5.1 ng/L. Both PFAS compounds were treated by the demonstration facility to nondetectable levels, as indicated in Table 4 (San Diego, 2012).

Water Quality Enhancement With Direct Potable Reuse in Texas

The communities of West Texas have struggled with multiple severe drought events over the last few decades. In the wake of diminished water supplies, the Colorado River Municipal Water District (CRMWD) recognized the need for alternatives to sufficiently provide water for its approximately 500,000 customers. To supplement the water supply for the City of Big Spring, Texas, CRMWD, in conjunction with the Ward County Well Field project, constructed the Big Spring Raw Water Production Facility (RWPF) in May 2013 (Steinle-Darling et al., 2016).

The RWPF produces 1.7 mgd of advancedtreated reclaimed water that is directly blended with water pumped from Moss Creek Lake, making it the first DPR facility in the U.S. (SteinleDarling et al., 2016). The RWPF receives the secondary effluent of the Big Spring WWTP. The RWPF treatment train includes two MF skids, two RO trains, UV/AOP process of hydrogen peroxide injection, and high-intensity UV light. All membrane backwash and waste streams are returned to the WWTP, RO concentrate is discharged to Beal’s Creek, and product water is blended with water from Moss Creek Lake at less than 50 percent of the total flow.

Figure 3 shows a diagram of the treatment process and blending with the surface water (Steinle-Darling et al., 2016).

Beal’s Creek contains approximately 20,000 mg/L total dissolved solids (TDS), on average, indicating a significantly high salinity. As such, the CRMWD was authorized to obtain an industrial discharge permit from the Texas Pollutant Discharge Elimination System (TPDES) to expel the RO concentrate into Beal’s Creek. Although the RO concentrate is known to contain significant PFAS contamination, raw water reservoirs downstream of the RWPF discharge point are protected via stream redirection. The primary purpose of the redirection is to deposit the dissolved salts of Beal’s Creek into an evaporation pond, thus protecting the downstream reservoirs (Steinle-Darling et al., 2016). As a result, the RO concentrate is also redirected to the pond.

To ensure compliance with potable water quality standards, the Texas Water Development Board (TWDB) conducted a study to sample and test for PFAS concentrations in the product at the RWPF. From July 2014 to September 2015, samples from six locations were obtained during four major sampling events. The average concentration of the various PFAS compounds tested at five of the six locations is provided in Figure 4. As shown, PFAS concentrations achieved nondetect levels for both RO permeate and product water.

The figure indicates elevated PFAS concentrations at the Moss Creek Lake sampling location, which suggests that the RWPF product water enhances the water quality of blended water, in terms of PFAS concentrations (Steinle-Darling et al., 2016).

Engaging the Community

The major potable reuse deterrent is public perception, as the general public perceives reused water as contaminated and of lower quality (Hartley et al., 2019). This means that engaging the community is one of the most important steps to successfully implement any potable reuse project. Multiple utilities across the U.S. have undertaken extensive public outreach programs to educate the public about the advanced treatment processes used in potable reuse facilities and overall benefits of recycling water. Additional steps can be taken to emphasize how potable reuse facilities are improving water quality by tackling emerging contaminants (such as PFAS) that are prevalent in the environment and often in local water sources.

The communications and outreach plan provides the initial elements of a successful potable reuse project. Formulating such an outreach program will include several steps, outlined in Figure 5.

San Diego’s public outreach to educate residents about the safety and benefits of recycled water includes community tours of the Pure Water San Diego demonstration facility, workshops explaining the benefits of potable reuse, and distribution of educational material, such as brochures and videos. The city has a dedicated website that provides information about the program, answers frequently asked questions about potable reuse, and allows the general public to access the engineering reports generated through different stages of the Pure Water San Diego program implementation (San Diego, 2023).

In Texas, the CRMWD actively engaged the public in Big Spring through television, newspaper, and radio, and in public meetings. Residents were encouraged to reach out to the district and ask questions or request presentations to various clubs and associations (Scruggs et. al, 2020). The public outreach program generated public acceptance and support for the first DPR facility in the U.S.

Summary: New Incentives for Potable Reuse

Florida’s rapidly increasing population and diminishing freshwater sources are forcing

Continued on page 14

Continued from page 13 utilities to search for new alternative water supplies. In addition, PFAS chemicals are widely spread in conventional water sources across the U.S. Utilities in Florida and other states have successfully demonstrated the reliability and effectiveness of potable reuse treatment systems, while the regulators are moving toward establishing guidelines and regulations for potable reuse projects.

Public perception of recycled water for drinking is still a major hurdle that requires extensive public outreach and education programs to be overcome; however, information about PFAS removal, in addition to demonstrating the safety and water quality of potable reuse systems, might help communities accept this alternative water source more willingly.

Potable reuse facilities are well-suited to treat PFAS compounds because they already use the same advanced water treatment technologies that are effective against PFAS. Future MCLs on PFAS might motivate more utilities to choose recycled water as their new drinking water source to reap the benefits of a droughtresilient and environmentally sustainable water supply that will ensure compliance with future regulations.

References

• California Environmental Protection Agency (CEPA). (2018, December 11). Water Quality Control Policy for Recycled Water. State Water Resources Control Board. https:// www.waterboards.ca.gov/water_issues/ programs/recycled_water/policy.html.

• City of Altamonte Springs. (2017, August). The City of Altamonte Springs Explores Ways to Combat Future Water Shortages With its New pureAlta Water Project. https:// altamonte.org/DocumentCenter/View/6960/ Altamonte-Springs-pureALTA-ProjectPress-Release.

• City of Altamonte Springs. (2017, October). pureALTA Wins National Award for Water Treatment Project. https://altamonte. org/DocumentCenter/View/6961/2017pureALTA-WateReuse-Award-Press-Release.

• City of Altamonte Springs. (2018, September). City of Altamonte Springs Ranks Top in the World for Innovative Water Project. https://altamonte.org/DocumentCenter/ View/6959/2018-pureALTA-IWA-AwardPress-Release.

• City of San Diego (2016). San Diego’s Pure Water Program. https://www.sandiego.gov/ sites/default/files/pure_water_brochure_v9_ final_0.pdf.

• City of San Diego (2021). The City of San Diego, Pure Water San Diego. 2021 Annual Report: A Year in Review. https://www.sandiego.gov/sites/ default/files/2021_annual_report_a_year_in_ review-final.pdf.

• City of San Diego (n.d.). Informational Material. Retrieved February 12, 2023. https://www. sandiego.gov/public-utilities/sustainability/ pure-water-sd/information.

• Florida Department of Environmental Protection (FDEP). (2021). Potable Reuse Rulemaking Public Workshop. https:// floridadep.gov/sites/default/files/PotableReuse_ PublicWorkshopPresentation01142021_ ForWebsite.pdf.

• Florida Department of Environmental Protection (FDEP). (2022, March). Per- and Polyfluoroalkyl Substances (PFAS) Dynamic Plan. floridadep.gov/sites/default/files/Dynamic_ Plan_March_2022.pdf.

• Florida Potable Reuse Commission. (2020, January). Framework for the Implementation of Potable Reuse in Florida. http://www. watereuseflorida.com/wp-content/uploads/ Framework-for-Potable-Reuse-in-FloridaFINAL-January-2020-web10495.pdf

• Florida Senate (Fl Senate), 2021. Senate Bill 64 Summary. https://www.flsenate.gov/ Committees/billsummaries/2021/html/2320.

• Hartley, K., Tortajada, C., & Biswas, A.K. (2019, November) A Formal Model Concerning Policy Strategies to Build Public Acceptance of Potable Water Reuse. Journal of Environmental Management. Volume 250. 109505. ISSN 0301-4797. https://doi.org/10.1016/j. jenvman.2019.109505.

• Kumar, P., Rodriguez-Gonzalez, L., Salveson, A., Ammerman, D., & Steinle-Darling, E. (2021, September). Per- and Polyfluoroalkyl Substance Removal in Carbon-Based Advanced Treatment for Potable Reuse. AWWA Water Science, e1244. https://doi.org/10.1002/aws2.1244.

• Martz, F., Torres, E., & Jackson, J.A. (2019, January). A Safe and Cost-Effective Alternative Water Supply for Potable Reuse. https:// meetingoftheminds.org/a-safe-cost-effectivealternative-water-supply-for-potablereuse-29464.

• Public Utilities Department (San Diego). (2012, November). Advanced Water Purification Demonstration Facility Preliminary Water Quality Monitoring Results. https://www. sandiego.gov/sites/default/files/legacy/water/ purewater/pdf/finalawpdfwebdata121101.pdf.

• Public Utilities Department (San Diego). (2019, April). Final Draft Title 22 Engineering Report North City Pure Water Project. City of San Diego. https://www.sandiego.gov/sites/default/ files/north_city_pure_water_project_final_ draft_title_22_engineering_report.pdf.

• Scruggs, C.E., Pratesi, C.B., & Fleck, J.R. (2020, July) Direct Potable Water Reuse in Five Arid Inland Communities: An Analysis of Factors Influencing Public Acceptance. Journal of Environmental Planning and Management. 63:8, 1470-1500, https://doi.org/10.1080/09640 568.2019.1671815.

• State Water Resource Control Board. (n.d.). Drinking Water Notification Levels. Retrieved February 10, 2023, from https://www. waterboards.ca.gov/drinking_water/certlic/ drinkingwater/NotificationLevels.html.

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• Steinle-Darling, E., Salveson, A., Sutherland, J., Dickenson, E., Hokanson, D., Trussell, S., & Stanford, B. (2016, December). Testing Water Quality in a Municipal Wastewater Effluent Treated to Drinking Water Standards (Vol. 1). Texas Water Development Board. https:// www.twdb.texas.gov/publications/reports/ contracted_reports/doc/1348321632_vol1. pdf?d=460646.9000000004.

• Steinle-Darling, E., Salveson, A., Sutherland, J., Dickenson, E., Hokanson, D., Trussell, S., & Stanford, B. (2016, December). Testing Water Quality in a Municipal Wastewater Effluent Treated to Drinking Water Standards (Vol. 2). Texas Water Development Board. https:// www.twdb.texas.gov/publications/reports/ contracted_reports/doc/1348321632_vol2. pdf?d=460646.9000000004.

• United States Census Bureau (Census). QuickFacts. Florida. Retrieved Feb. 12, 2023, from https://www.census.gov/quickfacts/fact/ table/FL/PST045221.

• U. S. Environmental Protection Agency (EPA). (2016). FACT SHEET: PFOA and PFOS Drinking Water Health Advisories. Office of Water Health and Ecological Criteria Division. https://www. epa.gov/sites/default/files/2016-06/documents/ drinkingwaterhealthadvisories_pfoa_pfos_ updated_5.31.16.pdf.

• U. S. Environmental Protection Agency (EPA). (2021). PFAS Strategic Roadmap: EPA’s Commitments to Action 2021 –2024. https://www.epa.gov/system/files/ documents/2021-10/pfas-roadmap_final-508. pdf.

• U. S. Environmental Protection Agency (EPA). (2022). EPA Announces New Drinking Water Health Advisories for PFAS Chemicals, $1 Billion in Bipartisan Infrastructure Law Funding to Strengthen Health Protections. https:// www.epa.gov/newsreleases/epa-announcesnew-drinking-water-health-advisories-pfaschemicals-1-billion-bipartisan. S

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