Use of mature compost as filter media and the effect of packing depth on hydrogen sulfide removal from composting exhaust gases by biofiltration.

A study was conducted to investigate the utilization of mature compost as a biofilter medium for the removal of hydrogen sulfide (H2S) from the exhaust gases of the composting process. Source-selected kitchen waste from municipal solid waste was composted in a reactor, and the exhaust gas was passed through a biofilter packed with a 1:4 (wet weight) mixture of mature compost and sand. Two treatments were applied under sterilized and unsterilized conditions to quantify the contribution of microbial activity. The effect of packing depth on H2S removal efficiency was also studied. A global H2S removal efficiency of 51% was obtained in the biofilter for loading rates in the range of 0-429 mg H2S m-3 h-1. The adsorption capacity was the main factor affecting H2S removal efficiency, contributing 64.2% to the total removal efficiency, with microbial activity contributing 35.8%. The relationship between the cumulative amount of H2S removed and the packing height was well-described by a linear equation. The equation indicated that 99% H2S removal efficiency could be achieved using a packing height of 96 cm for unsterilized packing material or 158 cm for sterilized packing material.