Hydrogen sulfide removal from a biogas mimic by biofiltration under anoxic conditions

The biofiltration of hydrogen sulfide present in a biogas mimic under anoxic conditions was performed using expanded schist and cellular concrete waste as packing materials. The impact of various parameters, such as H2S concentrations, Empty Bed Residence Time (EBRT) and molar ratio N/S, on the performances of biofilters was evaluated. At an EBRT of 300 s, expanded schist efficiently treated H2S concentrations up to 1100 ppmv (maximum elimination capacity ECmax = 30.3 g m−3 h−1). At an EBRT of 240 s, cellular concrete waste was an effective material for the treatment of concentrations of H2S up to 900 ppmv (ECmax = 25.2 g m−3 h−1). Whatever the molar ratio N/S selected, sulfate and elemental sulfur were produced in the biofilters. Both materials presented a satisfactory mechanical behavior with low pressure drops. Therefore, this study showed that biofilters could be used to treat moderate concentrations of H2S in biogas under anoxic conditions.