Biological elimination of a high concentration of hydrogen sulfide from landfill biogas

Hydrogen sulfide (H₂S) is one of the main contaminants found in biogas, which is one of the end products of the anaerobic biodegradation of proteins and other sulfur-containing compounds in solid waste. The presence of H₂S is one of the factors limiting the valorization of biogas. To valorize biogas, H₂S must be removed. This study evaluated the performance of a pilot-scale biotrickling filter system on H₂S removal from landfill biogas. The biotrickling filter system, which was packed with stainless-steel pall rings and inoculated with an H₂S-oxidizing consortium, was designed to process 1 SCFM of biogas, which corresponds to an empty bed residence time (EBRT) of 3.9 min and was used to determine the removal efficiency of a high concentration of hydrogen sulfide from landfill biogas. The biofiltration system consisted of two biotrickling filters connected in series. Results indicate that the biofiltration system reduced H₂S concentration by 94 to 98% without reducing the methane concentration in the outlet biogas. The inlet concentration of hydrogen sulfide, supplied to the two-phase bioreactor, was in the range of 900 to 1500 ppmv, and the air flow rate was 0.1 CFM. The EBRTs of the two biotrickling filters were 3.9 and 0.9 min, respectively. Approximately 50 ± 15.7 ppmv of H₂S gas was detected in the outlet gas. The maximum elimination capacity of the biotrickling filter system was found to be 24 g H₂S·m^-3·h^-1, and the removal efficiency was 94 ± 4.4%. During the biological process, the performance of the biotrickling filter was not affected when the pH of the recirculated liquid decreased to 2-3. The overall performance of the biotrickling filter system was described using a modified Michaelis-Menten equation, and the K_s and V_m values for the biosystem were 34.7 ppmv and 20 g H₂S·m^-3·h^-1, respectively.