Since the 1990s, USEPA has provided risk-based Regional Screening Levels (RSLs) to assist in evaluating environmental monitoring and contaminant levels – e.g., in soil, air, and water at residential and industrial properties. EPA periodically updates the RSL tables to reflect new contaminants of concern and new chemical toxicity data. The May 2022 RSL tables have been expanded to include 14 per- and polyfluoroalkyl substances (PFAS). PFAS are a large family of emerging contaminants that are garnering significant interest due to their significant toxicity and widespread use in industrial and consumer products such as fire-fighting foam, fabric treatment, and some food packaging. The latest EPA RSL tables are available at: https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables
Additional info regarding ongoing efforts to address and treat PFAS are available by searching this website: https://www.scsengineers.com/ and then using the filter to narrow down returns to your interests.
Regulatory movement around PFAS is picking up; this year and next could be monumental around managing these toxic compounds in landfills and leachate. Operators should look out for proposed U.S. Environmental Protection Agency (EPA) rules in 2022 and final rules in 2023. Most notably, two PFAS categories, PFOA and PFOS, could be classified as hazardous wastes under the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), aka Superfund. Also, expect rules on monitoring and limiting PFAS in drinking water.
Amidst this regulatory activity, PFAS treatment research advances, which will be critical to landfill operators when they are charged with managing this very challenging stream. With existing options, it’s near impossible to destroy these “forever chemicals,” known for their carbon-fluorine bond, considered one of the strongest in nature.
SCS Engineers’ Gomathy Radhakrishna Iyer advises operators on what to look for to brace for regulatory change and advises them on their best defense—the treatment piece. She explains current options and potential technology breakthroughs on the horizon.
“On the legislative front, standardized guidance might not happen overnight. There’s much to learn, as leachate is not the same, including as it pertains to PFAS. Concentrations and compounds vary. So, EPA is gathering data and knowledge to inform policy and mitigation options moving forward,” Iyer says.
Today’s focus entails developing and validating methods to detect and measure PFAS in the environment. The EPA is evaluating technologies to reduce it and is trying to understand better the fate and transport of PFAS in landfills (including landfill gas, leachate, and waste).
While PFAS concentrations in leachate sent to publicly owned treatment plants (POTW) are unknown, the EPA 2023 rule aims to fill in the missing pieces. What is learned and subsequent decisions will be critical to landfill operators who depend on POTWs as a final destination for leachate and at a time when POTWs meet stringent guidelines on what they can accept. The EPA’s focus will begin with guidance on monitoring and reporting figures, including a list of PFAS to watch for in 2022.
In the meantime, the agency published interim guidance on destroying and disposing of PFAS, which it plans to update in fall 2023. The interim guidance identifies the information gap with regard to PFAS testing and monitoring, reiterating the need for further research to address the FY20 National Defense Authorization Act NDAA requirements. Operators can also look to SWANA treatment guidelines to help prepare for new rules.
Get ahead of the game by doing your homework on treatments, Iyer advises. POTWs have discharge limits, and once PFAS in leachate is weighed in with the existing constituent limits on permits, ensuring a disposal destination will call for proactive measures.
The discussion on treatments will be important. Iyer advises on staying up with expectations that may be in the pipeline, beginning by focusing on today’s commercially available options:
Comparing these methods, Iyer says, “Biological treatments work better simply as a pretreatment method, removing PFAS to some extent. Their performance may also only apply to non-biodegradable organic matter. Considering these limitations, the alternative of physical-chemical treatments is most often recommended by industry experts; they appear to be more effective as supported by data,” Iyer says.
Her preference is RO, the membrane-enabled separation process, which many treatment plants already use, or are considering, to remediate other constituents. “Because we know RO to be effective with other contaminants and PFAS, I think it’s a great gainer, especially if plants already use this method to treat leachate for other contaminants successfully,” she says.
RO requires relatively little operational expertise, while other physical-chemical methods, such as GAC and ion exchange, require some chemistry knowledge.
“With granular activated carbon and ion exchange, resins attach to contaminants in leachate. These approaches require pretreatment for organics removal, process understanding, and operator involvement. Conversely, with RO, you learn a fairly straightforward process and move through the steps,” she says.
But while physical-chemical treatments are the best readily available options today, each has limitations. RO leaves a residue requiring further treatment; then, the material is typically recirculated in landfills as a slurry or hauled to a POTW, meaning there is no guarantee they will not need to be addressed later. Other methods, such as GAC, are more energy-intensive and have limited sorbent capacity. Ion exchange, in particular, has difficulty removing short-chain PFAS, which persist in the environment.
When the time comes that PFAS have stringent discharge limit requirements, no one of these technologies may work as a standalone, so the search is on for more robust systems.
Several new treatments are under research; unlike their predecessors, they appear to break the chemical bond.
Iyer shares her take on each option:
“I’m especially interested in seeing how plasma treatment works in the real world versus the lab. The building costs can be higher, and leveraging electricity to break the bond is expensive. But the maintenance should be easy and relatively inexpensive compared to other technologies. It will be interesting to see how economical it would be for landfills over the long run.”
There is more to learn about each of these new technologies. Researchers are working to identify the adsorbents that best suit PFAS compound removal, whether short or long chains. With photocatalytic reaction, a research direction is exploring combining UV rays, a catalyst, and an oxidant to degrade PFAS.
“We know that the absorption options and photocatalytic concepts work well on strong contaminants,” Iyer says. She moves on to her thoughts on thermal treatment. She wants to know more about this particular option before weighing in. “I’m not sure how feasible this method will be for the operators. PFAS get destroyed at a temperature greater than 1,000 degrees Celsius. But for high quantities of leachate, this option could be expensive.”
Most EPA-funded research is based on these developing treatment processes. But there is plenty to evaluate to identify the best solutions in a given scenario. With that understanding, the agency is trying to understand the types and volumes of PFAS generated, how they change or degrade as they enter landfills, and where they originate. EPA is building a database to track this information to consider key characteristics of individual PFAS to help guide forthcoming guidance on treatments.
In the meantime, Iyer advises operators to pay close attention to evolving developments and communications from EPA.
We recently saw the memorandum from EPA on addressing PFAS discharges in EPA-issued NPDES permits. We will look for guidance to the state permitting authorities to address PFAS in NPDES permits soon and more information from the EPA’s roadmap.
At SCS, we use our time to learn about technologies, including what’s still under investigation and explore what seems to work. In addition, watch for guidance documents, not just from EPA but from research organizations such as EREF and universities. Do your due diligence and keep your eyes and ears open for EPA and your state regulatory authority announcements. Staying informed is the best strategy for landfill operators at this point.
SWANA is optimistic regarding the positive role modern MSW landfills can play in managing solid waste – such as carpeting and clothing – containing PFAS. By disposing of these products in landfills and effectively treating landfill leachate for PFAS removal, the solid waste industry can provide society with an effective and proven method of managing PFAS wastes.
In support of members, the SWANA Applied Research Foundation (ARF) has issued a report summarizing and analyzing management options and treatment technologies that can address PFAS chemicals contained in landfill leachate on November 10, 2021. PFAS Management and Treatment Options for Landfill Leachate is available to SWANA ARF subscribers.
The research findings presented in the resulting report are based on a comprehensive review of the literature and an analysis of the commercially-available PFAS treatment systems and other management options for landfill leachate.
The new report serves as a companion report to one published by the ARF in June 2021 on PFAS Fate and Transport in WTE Facilities, available in SWANA’s Reports List.
Across the industry, stakeholders agree the next few years will be critical in shaping how landfills deal with PFAS and how the public perceives it. Waste trade associations, scientists, and a host of organizations are in the midst of conducting a number of studies looking closely at the issue, PFAS treatment options, the positive impact of recycling, and regulatory policies.
While there are sites noted in the article, there’s no practical way for most companies and landfills to respond at this time responsibly. Additionally, landfills are unique; no two are alike. Most human exposure to PFAS occurs through contaminated food. The majority of landfill leachate is pre-treated at the landfill before going to a wastewater treatment plant, where additional treatment occurs before discharge.
According to EREF President Dr. Bryan Staley, in the article, “The relative impact of leachate as a human exposure pathway needs further evaluation to understand its relative degree of importance as it relates to health implications.”
Dr. Gomathy Radhakrishna Iyer, landfill leachate and design expert for SCS Engineers, said some operators are waiting to see what regulations may come even as they work on accounting for potential compliance issues and seeking solutions. “When the clients are thinking of upgrading their treatment plans, some are definitely taking into consideration PFAS treatment,” Radhakrishna Iyer said.
“You’re spending millions of dollars, you need to do your due diligence, right? At this point, consideration should be given to PFAS treatment during the feasibility stages,” she said.
Complementing the Interstate Technology and Regulatory Council’s – ITRC, PFAS Technical and Regulatory Guidance, the website now has ITRC Per- and Polyfluoroalkyl Substances – PFAS, and Risk Communication Fact Sheets available. The site and updated content replace older fact sheets with more detailed information and useful for those who wish to understand the discovery and manufacturing of PFAS, information about emerging health and environmental concerns, and PFAS releases to the environment with naming conventions and federal and state regulatory programs.
SCS Engineers’ professionals recommend further reading to understand specific chemicals or subgroups of chemicals under study to comprehend PFAA behavior in the environment. There are appropriate tools to develop a site-specific sampling and analysis program and considerations for site characterizations following a PFAS release.
We combine ITRC resources and our own to compile an updated library that we hope you find helpful. You can always contact one of our local Liquids Management or Landfill professionals too.
PFAS Behavior in the Environment
The Interstate Technology and Regulatory Council (ITRC) is a state-led coalition working to reduce barriers to the use of innovative air, water, waste, and remediation environmental technologies and processes. ITRC documents and training can support quality regulatory decision making while protecting human health and the environment. ITRC has public and private sector members from all 50 states and the District of Columbia and is a program of the Environmental Research Institute of the States (ERIS), a 501(c)(3) organization incorporated in the District of Columbia and managed by the Environmental Council of the States (ECOS).
SCS Engineers’ Gomathy Radhakrishna Iyer explains, “The structure of PFAs is a carbon and fluorine bond, and that bond is considered one of the strongest in nature. For industry, Chlorofluorocarbons (CFC), a volatile derivative of methane, ethane, and propane, creates problems globally after they’ve been released. Chlorofluorocarbons are strong greenhouse gases and are also responsible for the destruction of stratospheric ozone.
The most publicized of these compounds are those used as coolants in refrigeration and air conditioners, as propellants in spray cans and similar products, and as solvents for industrial purposes. Chlorofluorocarbons are far less abundant than carbon dioxide in the atmosphere. Still, they are 10,000 times more potent as a greenhouse gas and can remain in the atmosphere for more than 45 to 100 years. Reference
Iyer continues, “PFAS has the same kind of carbon-fluorine bond as CFC but linked to several C-F bonds like a chain making them even more inert and hard to degrade. Breaking this bond is what makes finding effective leachate treatments challenging, but certainly possible.”
It takes a savvy engineer to design safe and effective systems. We’re very proud of our Young Professionals like Gomathy – they’re smart and continue learning with the guidance of our VEPs – very experienced professionals.
Open positions at SCS Engineers for YPs and VEPs
PFAS are a class of synthetic fluorinated chemicals used in many industrial and consumer products, including defense‐related applications. They are persistent, found at low levels in the environment, and bio‐accumulate. Studies have shown these compounds being detected more often in surface water, sediments and/or bioaccumulated into fish tissue. Because of the greater affinity of longer chain per‐ and polyfluoroalkyl substances (PFASs) compounds for fish than other environmental matrices, certain compounds are often found in fish tissue, but not in the water or sediment. Table 1 shows average concentrations of PFOA and PFOS in landfill leachates around the world. The USEPA health advisory level is 70 ppt for PFOA and PFOS.
Table 1. Concentrations of PFAS compounds in Landfill Leachate around the world
Treatment Options for PFOS and PFOA
The removal of PFASs from drinking water has been the USEPA’s national priority. Recent discoveries of PFAS/PFOS in drinking water in multiple states in the US has heightened interest in these emerging contaminants. Federal, state, and local agencies are formulating regulatory limits that vary greatly. These limits seem to be centered on drinking water, but these developments are driving disposal of existing stores of chemicals containing PFAS/PFOS and environmental media contaminated with PFAS/PFOS
Treatment processes that can remove PFAS chemicals from drinking water may include high-pressure membrane systems such as RO, granular activated carbon (GAC), or ion exchange as shown in Figure 1. The more conventional water treatment technologies such as (e.g., aeration) are not typically effective.
Figure 1. PFAS Removal Processes (a) Membranes, (b) GAC and (c) Ion Exchange Resins
Landfill Leachate RO Treatment Plant – New Hanover County, North Carolina
New Hanover County upgraded its leachate treatment system to meet stricter regulatory standards for surface water discharges, particularly standards relating to metals (arsenic) and ammonia. Sampling by NC DEQ showed the new RO plant is filtering out PFAS. Table 2 shows the results from February 2019.
Figure 2. New Hanover County Leachate and PFAS Treatment Plant
Table 2. Concentrations of PFAS compounds in Leachate at New Hanover County Landfill
|PFAS Constituent||Raw||Treated||Surface water|
|PFOA (ppt)||1,250||< 0.6||3.9|
|PFOS (ppt)||228||< 0.6||7.1|
Comparison of GAC Types for PFOA and PFOS Removal
Four different types of GAC, i.e., Re-agglomerated Bituminous, Lignite, Enhanced Coconut and Enhanced Coconut (Blend) were evaluated under identical operating conditions and influent water quality. Figure 4 shows results from these four GAC products for PFOA/PFOS removal vs time.
Figure 4. GAC Treatability study for removal of PFOA and PFOS
Re-agglomerated bituminous coal GAC (FILTRASORB) significantly outperformed: Lignite, Enhanced Coconut and Enhanced Coconut (Blend).
PFAS compounds are of concern because they do not break down in the environment, bioaccumulate in humans and biota, and may pose risks to human health
GAC, Synthetic adsorbent, and ion exchange resins are widely used for PFAS removal. Capacity and leakage of PFASs into the treated water varies depending on the specific PFASs, the type of adsorbent used.
PFAS removal may be influenced by pH, water temperature, contact time, Natural Organic Matter, and chlorine. For complete PFAS removal, a polishing may be required.
Disposal methods for PFAS waste streams include high-temperature incineration or landfilling. Landfilling is not favored since the PFAS load would increase, and many landfills will not accept PFAS waste.
About the Author: Dr. deSilva is SCS’s Director of Wastewater Treatment. He has 30 years of progressive experience in wastewater engineering, from concept through construction and start-up, and is an international leader in operations and maintenance, energy management, solids handling processes, construction management, and commissioning wastewater treatment plants (WWTP) around the world.
Per- and poly-fluoroalkyl substances (PFAS) are receiving increasing attention from regulators and the media. Within this large group of compounds, much of the focus has been on two long-chain compounds that are non-biodegradable in the environment: PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid).
Long detected in most people’s bodies, research now shows how “forever chemicals” like PFAS accumulate and can take years to leave. Scientists have even tracked them in biosolids and leafy greens like kale. Recent studies have linked widely used PFAS, including the varieties called PFOA and PFOS, to reduced immune response and cancer. PFAS have been used in coatings for textiles, paper products, cookware, to create some firefighting foams and in many other applications.
Testing of large public water systems across the country in 2013 through 2015 found PFAS detected in approximately 4 percent of the water systems, with concentrations above the USEPA drinking water health advisory level (70 parts per trillion) in approximately 1 percent (from ITRC Fact Sheet). Sources of higher concentrations have included industrial sites and locations were aqueous film-forming foam (AFFF) containing PFAS has been repeatedly used for fire fighting or training. Source identification is more difficult for more widespread low-level PFAS levels.
With the EPA positioned to take serious action on PFAS in 2020 and beyond, regulators in many states have already started to implement their own measures, while state and federal courts are beginning to address legal issues surrounding this emerging contaminant. State actions have resulted in a variety of state groundwater standards for specific PFAS compounds, including some that are significantly lower than the USEPA advisory levels. These changes mean new potential liabilities and consequences for organizations that manufacture, use, or sell PFAS or PFAS-containing products, and also for the current owners of properties affected by historic PFAS use. If you operate a landfill or own a site with PFAS history this may be something you need to discuss and plan now.
Questions for property owners, property purchasers, and manufacturers include:
If PFAS treatment or remediation is required, a number of established options to remove PFAS from contaminated soil and groundwater are available, including activated carbon, ion exchange or high-pressure membrane systems. On-site treatment options, including in-situ or ex-situ alternatives, the management of reject streams with concentrated PFAS waste where applicable, are also available.
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Need assistance with PFAS or have an idea that you would like to discuss? Contact , or find the SCS Engineers location nearest you.
Per- and poly-fluoroalkyl substances (PFAS) are receiving increasing attention from regulators and the media. Within this large group of compounds, much of the focus has been on two long-chain compounds that are non-biodegradable in the environment: PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid). Long detected in most people’s bodies, research now shows how “forever chemicals” like PFAS accumulate and can take years to leave. They persist even when excreted through urine. Scientists have even tracked them in biosolids and leafy greens like kale. Recent studies have linked widely used PFAS, including the varieties called PFOA and PFOS, to reduced immune response and cancer. PFAS have been used in coatings for textiles, paper products, cookware, to create some firefighting foams and in many other applications.
Testing of large public water systems across the country in 2013 through 2015 found PFAS detected in approximately 4 percent of the water systems, with concentrations above the USEPA drinking water health advisory level (70 parts per trillion) in approximately 1 percent (from ITRC Fact Sheet.) Sources of higher concentrations have included industrial sites and locations were aqueous film-forming foam (AFFF) containing PFAS has been repeatedly used for fire fighting or training.
Source identification is more difficult for more widespread low-level PFAS levels. For example, in Madison, Wisconsin, PFAS have been detected in 14 of 23 municipal water supply wells, but the detected concentrations were below the USEPA’s health advisory levels for PFOA and PFOS. A study of potential PFAS sources near two of the Madison wells identified factories, fire stations, landfills, and sludge from sewage treatment plants as possible sources, but did not identify a specific source.
With the EPA positioned to take serious action on PFAS in late 2019 and 2020, regulators in many states have already started to implement their own measures, while state and federal courts are beginning to address legal issues surrounding this emerging contaminant. State actions have resulted in a variety of state groundwater standards for specific PFAS compounds, including some that are significantly lower than the USEPA advisory levels. These changes mean new potential liabilities and consequences for organizations that manufacture, use, or sell PFAS or PFAS-containing products, and also for the current owners of properties affected by historic PFAS use.
Questions for manufacturers, property owners, and property purchasers include:
If remediation is required, a number of established options to remove PFAS from contaminated soil and groundwater are available, including activated carbon, ion exchange or high-pressure membrane systems. On-site treatment options, including the management of reject streams where applicable, are also available.
Do You Need Help?
Use these resources to explore more about PFAS each is linked to helpful articles and information.
We recommend reading this article series to stay abreast of relevant knowledge from Bryan Staley, president and CEO of the Environmental Research & Education Foundation (EREF); Anne Germain, vice president of technical and regulatory affairs for the National Waste & Recycling Association (NWRA); Viraj deSilva, SCS Engineers wastewater treatment director; and testing results from New Hanover County whose capital investment in landfill infrastructure has proven to successfully treat effluent water to meet higher standards.