The continuing demand for improved process economy and efficiency has led to investigations into microbiological
alternatives to conventional methods. The biofiltration process is most effective when applied to dilute, easily biodegradable waste gases. A number of ways of using biofiltration for H2S removal by employing some specific packing materials as carriers and breeding appropriate microorganisms to purify waste gases have been studied . Biofilters were originally developed by utilizing soils as carriers; however, soils are limited in their effectiveness since they are prone to short-circuiting and clogging. Compost is inexpensive and purifies waste gases well, but it suffers from aging effects that create short-circuiting of the biofilter and further decrease the effectiveness of the biofilter. Activated carbons also perform well, but they are too expensive to justify the efficiency differenc.