PFAS Disposal Options

PFAS (per- and polyfluoroalkyl substances) are a group of man-made chemicals used in water and stain repellents, nonstick coatings, cleaning products, firefighting foams, and more. The last few decades have brought increasing awareness to the adverse health and environmental concerns that PFAS present - enough to capture the attention of regulatory agencies like the EU and EPA. Perfluorooctanoic acid (PFOA) is probably the most well-known PFAS chemical and is the target of many PFAS-reducing regulations. In 2006 the PFOA Stewardship Program saw eight manufacturing companies agree to reduce PFOA emissions by 2019 and eliminate PFOA and PFOS production in the US by 2015. These goals were met, but thousands more PFAS chemicals are being produced. 

As of late summer, 2019, various bills regarding regulating the disposal of PFAS containing substances, as well as cataloging and remediation of PFAS contaminated sites are floating around congress. Existing and proposed regulations and legislation target PFAS in drinking water at the ppt (part per trillion) level of detection and enforcement, as compared to many drinking water standards that are in the ppm or ppb levels. Remember a trillion is a million millions. These low levels coupled with the ubiquitous nature of PFAS makes sampling and analysis difficult, since samples can be cross contaminated by the sampler or potentially the analyst.

As far as treatment and disposal options go for PFAS containing materials, it is important to understand what media type is being treated and what the ultimate goals are. It is also imperative, since the PFAS chemicals vary greatly in chemical makeup and properties, that the treatment option is appropriate for the type of PFAS. The environmental media contaminated with PFAS includes soils and waters (drinking water, wastewater, ground water, etc.). There are also concentrated forms of PFAS, such as aqueous fire fighting foams (AFFF). You must also consider the types of treatment, which include separation and destruction, as well as the option of disposal. 

Available separation technologies for waters include granular or powdered activated carbon (GAC or PAC), ion exchange, reverse osmosis, and customized media. These vary greatly in capital expense, operational expense, interference of co-contaminants, effectiveness for short vs. long chain PFAS, and volume and characteristics of byproduct (waste) produced. Even after a separation technology is applied, the byproduct must then be destroyed or disposed.

Destruction of PFAS is a tricky subject. PFAS are generally made by chemical oxidation, there has not been enough demonstrated evidence of oxidation techniques resulting in defluorination of PFAS compounds. The essence of treating PFAS is to destroy the carbon-fluoride bonds. This bond is one of the strongest chemical bonds, and the only known, proven method for destroying this bond is high temperature incineration.

Disposal options include landfilling and deep well injection. These options are legal, but may carry long term CERCLA liability concerns.

While each of these methods clearly have their drawbacks, the prevalence and persistence of PFAS makes it uniquely challenging to treat, and the current consensus is more research needs to be conducted in order to determine the best option for disposing of these hazardous chemicals.