With the typical composition of biogas described earlier, the biogas can be readily used with engine in term of the heating content. However, the H2S in biogas, which is found to range between as low as about 50–10,000 ppm depending on the feed material composition to the digester [4], can cause corrosion to the engine and metal parts via emission of SO2 from combustion, especially when the engine is not operated continuously, as well as toxic H2S/SO2 concentrations in the workplace. Therefore, H2S must be removed prior to further utilisation.