Chiang Mai Journal of Science

   Hydrogen sulfide (H₂S) is a hazardous gas commonly found in biogas systems; it causes problems in biogas utilization because H₂S is highly corrosive to engines, gas storage tanks, and generators. The purpose of this research was to study the biogas upgrading by removing H₂S using SCM440 type steel wool (Fe₂O₃) adsorption combined with water absorption. The biogas upgrading column was operated at a biogas flow rate of 0.5–3 l/min, with 10–50 g of treated Fe₂O₃ adsorbent packed in the middle of the column, and 60–300 ml of water contained at the bottom of the column. The optimal conditions obtained by the RSM for maximum H₂S removal were 1 l/min gas flow rate, 40 g Fe₂O₃ and 240 ml water, can be H₂S removal of 50.79 g/m³ biogas. Statistical, ANOVA analysis showed that Fe₂O₃ was the most significant factor followed by water and gas flow rate. RSM models showed acceptable prediction of experimental data with maximum R² value of 0.9804. The Fe₂O₃ regeneration conditions were examined at air flow rates of 1–4 l/min, regeneration times of 1–4 h, and 1–4 repeated uses for H₂S removal. The optimum condition was found at a 2 l/min air flow rate for 2 h, resulting in a maximum H₂S removal of 97.39%. Hence, the Fe₂O₃ adsorbent combined with water absorption technique has high potential for environmentally friendly and low-cost removal of H₂S from biogas at an industrial level.