Lab-scale Evaluation of PFAS Decomposition and Flue Gas Qualities from Biosolids Incineration Process

The presence of perfluorinated alkylated substances (PFAS) in municipal wastewater sludge/biosolids is a growing concern for facilities that rely on land application as the main disposal method. Thermal combustion is considered a viable solution to decompose the PFAS compounds in the biosolids. Two bench scale combustion studies were conducted at a combustion temperature of 1150oC with two gas residence times (GRT) of 2 and 4 seconds, respectively. The ash residuals generated from the two studies meet the PFAS requirements for biosolids land application imposed by the Stage of Michigan. The estimated levels of PFAS constituents as measured in the flue gas indicates the potential of the combustion technology to meet the air emission requirements at 70 ng/m3 for PFOA and PFOS also imposed by the State of Michigan. The GST of 4 seconds at a combustion temperature of 1,150oC improved the decomposition of the PFAS compounds measured and lowered the air emission for PFOA and PFOS, compared to the 2 seconds GRT at the same temperature.