Method of elimination of poly- and perfluoroalkyl substances (pfas) in a wastewater biosolids gasification process using a thermal oxidizer and hydrated lime injection

Abstract

Apparatus and methods to eliminate PFAS from wastewater biosolids through fluidized bed gasification. The gasifier decomposes the PFAS in the biosolids at temperatures of 900-1800° F. Syngas exits the gasifier which is coupled to a thermal oxidizer and combusts at temperatures of 1600-2600° F. This decomposes PFAS in the syngas and creates flue gas. Heat is recovered from the flue gas by cooling the flue gas to temperatures of 400-1200° F. in a heat exchanger coupled with the thermal oxidizer. Various methods inject moisture into the gas stream, controlling temperature through evaporative cooling and/or injecting chemicals that react with gas stream components. Cooled flue gas mixes with hydrated lime capturing decomposed PFAS molecules with spent lime filtered from the cooled flue gas using a filter system that may incorporate catalyst impregnated filter elements, eliminating PFAS from wastewater biosolids and controlling emissions in the resulting flue gas.