Hydrogen sulfide and siloxane related problems in biogas production plants lead to the implementation of desulfurization unit. Among different available desulfurization technologies of AAT, its microbial desulfurization benefits a high H2S removal capacity so that it can remove up to 99% of the content. Its operation is based on the contact between the inlet H2S-rich biogas and the aerobic bacteria attached to the packing (PP pall ring). The bacteria-rich packing is continuously fed by an organic solution containing the needed elements for the operation of bacteria together with a process water to control the drops in PH, caused by H2SO4. The packing is maintained at a constant temperature by the help of a heat exchanger, regarding the optimum range for the bacteria. In the outlet, the H2S concentration can be lowered by about 50 ppm.