OPTIMIZATION POTENTIAL OF BIOGAS PRODUCTION IN ANAEROBIC DIGESTERS ON MUNICIPAL WASTEWATER TREATMENT PLANTS

Abstract

The biogas produced during the anaerobic digestion of wastewater sludge is often burned in order to reduce the greenhouse gas emissions. Very little of this biogas is used as an energy source in Brazil. In the present paper the volumes and characteristics of biogas produced at different anaerobic digesters in pilot and real scale in Brazil and Germany were determined, in order to evaluate the possibility of improvement of the anaerobic digester efficiency and study the availability of this biogas as alternative fuel. The biogas productions at the pilot plant experiments rendered 248 and 319 L biogas/kg dried solids (anaerobic digester sludge from bio filter and activated sludge processes). The biogas productions for real scale Wastewater Treatment plants (WWT) rendered 114, 480 and 310 L biogas/kg dried solids for three different activated sludge WWT plants, respectively in Brazil, Germany and Germany. The CH4 and CO2 concentrations of the biogas were between 65 – 70% and 30 – 35%. H2S concentrations in the biogas were lower than 200 ppm for the real scale German WWT plants, between 600 and 800 for the pilot plants (Brazil) and higher than 1000 ppm for the real scale WWT plants in Brazil. The use of biogas as vehicle fuel can be economically feasible when compared to the fuel price.

KeyWords: Biogas, Anaerobic Digestion, Bio fuel