Biological desulfurization of biogas by a controlled aeration system

Abstract

The excessive demand of modern society for resources implies the need for development, propagation and use of energy sources more interesting from the environmental and economic point of view. Biogas is a potential alternative, originating from anaerobic degradation composed essentially of methane (CH4), carbon dioxide (CO2) and traces of other gases such as hydrogen sulfide (H2S) and moisture. To enable its use, a purification process is necessary, especially with regard to H2S, since it has characteristics that cause corrosion of equipment and toxicity to human health. This study aims to implement a biological desulfurization system for biogas generated from the anaerobic digestion of the effluent treatment system in an egg processing company. Both the monitoring of the biogas composition and the control of air injection into the system were performed automatically from a device from the manufacturer Awite, which proved to be interesting for full-scale applications. The system showed removal efficiency of up to 71.63% (June 17th)  in the concentration of H2S at the exit of the biodigester when the extreme values obtained were used, and removal of 61.23% when the selected period was considered. Still, the temperature behavior was shown to influence the variable [H2S] in a directly proportional way. However, it was noticeable the restriction of the efficiency of the technique especially due to the low content of solids in the effluent and a need for adaptation in the engineering of the reactor.