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.