Per- and polyfluoroalkyl substances (PFAS’s) are in our water and our biosolids (treated domestic Sewage Sludge), and they’re a big problem if left untreated.
PFAS is a group of chemical compounds that were developed in the 1940s by 3M and Dupont for use in producing non-stick consumer products like Teflon, stain-resistant fabrics and fire fighting foams. Over several decades PFAS and related chemicals like PFOA and PFOS were discharged into the air and into receiving bodies of water. They were also spread as biosolids when applied to farmland or disposed of in landfills.
While PFAS compounds are no longer in production, PFAS substances can be found in the bloodstream of >98% of the U.S. population as they migrate through the soil and into our water supply.
Because these compounds are highly toxic in very low concentrations, in 2016 the EPA issued a Health Advisory Level (HAL) of 70 parts per trillion (ppt) for PFOA and PFOS. Risk assessments are currently being conducted to define remediation levels and effluent limits further.
Finally, PFAS’s are known as persistent compounds that don’t biodegrade, so they stay in the ecosystem for exceptionally long periods, and complicating matters, many PFAS formulations are still unknown, leading to uncertain impacts on health and the environment.
Removing PFAS in Water and Biosolids
Water: Proven systems can remove or eliminate PFAS’s from water when designed correctly. Granular activated carbon (GAC) and reverse osmosis treatment systems successfully remove PFOA and PFOS to non-detect levels, and have been in use throughout the United States for many years.
Biosolids: It has been long thought that Pyrolysis (defined as the thermal decomposition of organic material through the application of heat without the addition of extra oxygen) could be successfully applied as a mechanism to destroy PFAS compounds, but until recently the concept had not been verified.
On September 12th, 2019 Bioforcetech Corporation provided anaerobically digested biosolids (at 91% solid content) to Vista Analytical Laboratory in El Dorado Hills, CA for analysis. The input biosolids were processed through BFT’s P-FIVE pyrolysis reactor utilizing a flameless technology that results in the transformation of the treated sewage sludge into a sustainable product called Biochar.
The Biosolids and Biochar (before and after Pyrolysis) analysis of 38 PFAS and PFOA compounds are shown below in table form, followed by a brief description of the Pyrolysis process and the Bioforcetech P-FIVE Reactor.
Even though the methods for analyzing these compounds have not been defined yet, EPA had drafted a solid-phase extraction/isotope dilution (SPE-ID). Bioforcetech has conducted an internal study to evaluate the fate of 38 PFAS and PFOAS compounds using this method. The results are published in this article for the first time showing the P-FIVE Reactor as an effective method for removing PFAS and PFOA from municipal Biosolids at an industrial scale.