Pilot-scale chemical–biological system for efficient H2S removal from biogas

A pilot-scale chemical–biological process was performed efficiently to remove corrosive H2S from biogas. Consecutive 356-d livestock biogas purification was conducted at various H2S loading rates. The average inlet H2S concentration was 3542 ppm, and a removal efficiency of 95% was achieved with gas retention time of 288 s. This system showed robust performance during operation with stable parameters. Purified biogas with an average of 59% CH4 was collected for power production. Moreover, 28.3 kW h of power was produced by using a 30 kW biogas generator under 300 LPM biogas flow rate. During the 30-d shut down test, the jarosite formation resulted in pH decrease and appearance of Leptospirillum sp. and Sulfobacillus sp. in the bioreactor. However, the cell density of the inoculated Acidithiobacillus ferrooxidans was maintained above 5 × 107 CFU/g-AC during long-term operation. Thus, given the successful H2S elimination, the chemical–biological process is a feasible system for biogas purification.