Impact and abatement of siloxanes in the Bucklin Point WWTF anaerobic digestion process

Abstract

The biogas produced at the Bucklin Point Wastewater Treatment Facility contained a high concentration of siloxane compounds. A manufacturer of personal care products was found to be the major source of the siloxanes. Much of the siloxane that the manufacturer discharged into the sewage collection system entered the anaerobic digestion system, where a portion was released into the biogas depending on the siloxane concentration and the amount of volatile solids that were digested. All of the siloxanes in the biogas likely oxidized to silica when the biogas was combusted, and a portion of the silica deposited in the boiler and impeded heat transfer efficiency by impacting the overall heat transfer coefficient. Siloxanes were condensed from the biogas at 34°F and the resulting concentrations were comparable to the concentrations predicted by theory.