Public health leaders are concerned that per- and polyfluoroalkyl substances (PFAS) use has grown rapidly since their invention in the early 1930s. As their unique properties have been leveraged to add heat-resistance, oil-repellency and waterproof benefits to a wide range of consumer products, these same properties have been the reason PFAS have been found in the environment.
The use of PFAS in many consumer products has resulted in management complexities for public service sectors tasked with managing waste streams. Municipal solid waste (MSW) landfills provide an essential public service that ensures people and the environment are protected by properly managing society’s nonhazardous wastes. Landfills are similar to wastewater treatment plants as both are “passive receivers” of waste streams containing PFAS and are not manufacturers or users of these chemicals. These essential public services now have the burden of managing PFAS waste in the face of growing public and regulatory scrutiny.
Jeremy O’Brien, director of applied research for the Solid Waste Association of North America (SWANA), says, “MSW landfills provide a safe and effective method of isolating PFAS compounds from the environment and human and animal contact.”
Silver Spring, Maryland-based SWANA’s data show that more than 90 percent of the PFAS entering a landfill remains sequestered in a lined, carefully constructed facility that is eventually capped to prevent the intrusion of further moisture when it is closed. The two major byproducts of a landfill—disposal leachate and landfill gas—are required to be collected and treated or combusted before being discharged to the environment.
O’Brien and SWANA have taken the position that landfill managers have a number of options available to address the issue of PFAS in leachate.
Treating leachate on-site for PFAS removal
Commercially proven options for treating leachate at the landfill for PFAS removal are available. These include granular activated carbon (GAC) following biological treatment of leachate through a membrane bioreactor or similar conventional leachate treatment system. Ion exchange (IX) is likely to work in this capacity as well but has not been demonstrated yet to do so. High-pressure reverse osmosis (RO) is another commercially proven process for PFAS leachate treatment that does not require leachate pretreatment through a membrane bioreactor (MBR) or similar conventional wastewater treatment process, according to industry experts. Another promising treatment for the effective removal of PFAS from raw leachate is foam fractionation, which generates a relatively low volume of residue compared with other concentration methods, experts say. All of these treatment options produce concentrated PFAS residuals that must be disposed of in hazardous waste landfills or destroyed to remove them from the environment.
Since 2017, Parsons Corp., a Chantilly, Virginia-based environmental services, engineering and infrastructure company, has been conducting groundwater and drinking water investigations in the vicinity of inactive landfills across New York state. This program, known as the Inactive Landfill Initiative (ILI), is being conducted on behalf of the NYS Department of Environmental Conservation under The Clean Water Infrastructure Act of 2017, which included the addition of Title 12 (Mitigation and Remediation of Certain Solid Waste Sites and Drinking Water Contamination) to Article 27 of the Environmental Conservation Law. Under Title 12, the ILI has focused on inactive solid waste disposal sites and their potential impact on New York’s drinking water supply with an emphasis on emerging contaminants, including PFAS and 1,4-dioxane.
Early in the New York program, it focused on creating a data inventory on the nearly 2,000 inactive solid waste disposal sites and landfills within the state, including assembling available records and conducting site visits to gather basic site information. A ranking system was developed to use data collected to prioritize those sites for groundwater investigation, and standardized protocols were established to provide continuity in investigations conducted.
To date, hundreds of landfill sites have been investigated for groundwater and drinking water, with new investigations being completed continuously. Overall, the results of the investigation activities have shown that the presence of PFAS compounds in groundwater near inactive landfill facilities is relatively common. Two PFAS compounds of concern for this program are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) because of their association with increased cancer risk and other health impacts. Levels of PFOA and PFOS in groundwater were found at concentrations exceeding the New York State maximum contaminant levels (NYS MCLs) in drinking water (10 parts per trillion each of PFOA and PFOS) at approximately 70 percent of landfills investigated to date. Comparatively, program results show a less frequent distribution of 1,4-dioxane in groundwater, with groundwater levels found at levels exceeding the NYS MCL (1 parts per billion) at 27 percent of the landfills.
MSW landfills and municipal wastewater treatment plants (WWTPs) often have a symbiotic relationship through the treatment of leachate at WWTPs and the landfilling of biosolids from WWTPs. It would benefit landfill managers to formally establish (in writing) a long-term PFAS management strategy where the landfill could dispose of WWTP biosolids if the WWTP agrees to treat the leachate generated by the landfill. As regulations surrounding PFAS increase, partnerships such as these could become increasingly important.