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Pyrolysis Processing of PFAS-Impacted Biosolids, a Pilot Study
Citation:
Thoma, E., R. Wright, I. George, M. Krause, D. Presezzi, V. Villa, W. Preston, P. Deshmukh, P. Kauppi, AND P. Zemek. Pyrolysis Processing of PFAS-Impacted Biosolids, a Pilot Study. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION. Air & Waste Management Association, Pittsburgh, PA, , NA, (2022). https://doi.org/10.1080/10962247.2021.2009935
Impact/Purpose:
PFAS chemicals have a very strong carbon-fluorine chemical bond, making them difficult to destroy leading to persistence in the environment. The ubiquitous nature of PFAS and increasing public concerns have underscored the need for validated solutions to manage PFAS contaminated media and waste for EPA Programs, Regions, states, and Tribes. The following product explores early research on treamtent of PFAS-impacted biosolids using pyrolysis.
Description:
Concentrations of per- and poly-fluoroalkyl substances (PFAS) present in wastewater treatment biosolids is a growing concern. Pyrolysis is a thermal treatment technology for biosolids that can produce a useful biochar product with reduced levels of PFAS and other contaminants. In August 2020, a limited-scope study investigated target PFAS removal of a commercial pyrolysis system processing biosolids with analysis of 41 target PFAS compounds in biosolids and biochar performed by two independent laboratories. The concentrations of 21 detected target compounds in the input biosolids ranged between approximately 2 µg/kg and 85 µg/kg. No PFAS compounds were detected in the biochar. The PFAS concentrations in the biochar were assumed to equal the compounds’ minimum detection limits (MDLs). The pyrolysis system’s target PFAS removal efficiencies (REs) were estimated to range between >81.32% and >99.96% (mean = >97.39%) with the lowest REs being associated with the lowest detected PFAS concentrations and the highest MDLs. No information on non-target PFAS compounds in influent or effluent media or products of incomplete combustion were considered. Select gaseous emissions were measured by Fourier transform infrared spectroscopy and gas chromatography time-of-flight mass spectrometry to provide additional information on air emissions after process controls. This limited-scope study indicated that additional research to further understand this process is warranted.
