Desulfurisation of biogas by biofiltration

Abstract

[Abstract] A biofiltration system to eliminate volatile fatty acids (VFAs) and hydrogen sulfide (H2S), using a microbial consortia, was established. The characterization of lava rock, vermiculite and glass rings, as potential packing materials, was previously performed. Vermiculite showed higher VFAs degradation rates than the ones obtained using lava rock; however, some compaction was noticed when this material was used as support. In the lava rock biofilter (1.7 L packed volume) acetic (AA) and propionic (PA) acids were completely removed from the gas and liquid phase, reaching 100% of removal efficiency (RE). Maximum elimination capacities (ECmax) for AA and PA in gaseous phase were 15.2 and 24.5 g/m3 bioifilterh, respectively; while in the liquid phase an ECmax of 76.3 and 122.5 g/m3 bioifilterh were attained. Empty bed resident times (EBRT) of 85 and 31 s were assessed for increasing H2S inlet loads (36 - 396 g/m3h) into the biofilter. At 85 s, an ECmax of 142 g/m3 bioifilterh was determined, with RE of around 99% for all the evaluated inlet loads. At 31 s, a maximum EC of 232 g/m3 bioifilterh and a RE of 95 % were found. Complete removal of VFA and H2S from the biogas was obtained in the lava rock biofilter.