Methane biofiltration for the treatment of a simulated diluted biogas emission containing ammonia and hydrogen sulfide

Abstract

Fugitive methane emissions impair the physical and chemical stability of the atmosphere. Biological systems, such as biofilters, have been proposed as a feasible technology for the abatement of CH4 in diluted emissions (<5% [CH4]). Other gases, such as NH3 and H2S, are also present in these emissions; and they could be detrimental for the performance of biological CH4 abatement strategies. The objective of this work was to establish the magnitude of the impact on the biofiltration of CH4 due to the presence of NH3 and H2S.A methane biofiltration system operating at load of 10 gCH4m-3h−1 was affected by the presence of NH3 and H2S in a synthetic diffuse stream, where the elimination capacity (5.5 gCH4m-3h−1) and efficiency (55%) varied significantly. A combination of 100 ppmv of NH3 and 100 ppmv of H2S decreased the capacity by 17% with respect to the unexposed biofilter while 500 ppmv of NH3 and 300 ppmv of H2S shrink the capacity by 26%. Separately, H2S decreased the methane elimination capacity by 11% under 150 ppmv and 20% when 300 ppmv was supplied. In the case of NH3, the presence of 100 ppmv and 300 ppmv of NH3 increases the methane elimination capacity by 35% and 16%, respectively. A reduction of 32% in the elimination capacity was observed under 1000 ppmv of NH3. We contribute with numerical evidence by which methane biofiltration was affected by secondary gases on a concentration range similar to those in waste methane diffuse stream, establishing the concentration ranges of H2S and NH3 at which it is possible to optimize the process of methane biofiltration and under which performance could be reduced.