Experimental analysis of hydrogen sulfide removal from biogas using a biofilter containing cellular concrete waste and biochar

This study investigates the removal efficiency of hydrogen sulfide (H₂S) from biogas using a biofilter packed with cellular lightweight concrete (CLC) waste and biochar. A laboratory-scale biofilter was designed and tested under varying operational and environmental conditions, including inlet H₂S concentrations (100–2000 ppm), gas flow rates (0.2–1.0 L/min), temperature (25–35 °C), and humidity (70–90%). The results demonstrated that H₂S removal efficiency reached 95% at low air flow rates and 91% under low H₂S concentrations. In comparison, efficiency declined to 88% at high air flow rates and 87% at high H₂S concentrations. The combination of biochar’s adsorption properties and Fe₂CO₃-modified CLC waste’s catalytic oxidation contributed to the biofilter’s high efficiency and stability. These findings suggest that hybrid biofilters incorporating waste-derived materials provide an environmentally sustainable and cost-effective alternative for biogas purification compared to conventional chemical and physical methods.