On-site Removal of H2S from Biogas Produced by Food Waste using an Aerobic Sludge Biofilter for Steam Reforming Processing

Abstract

H2S in biogas was removed by sludge-loaded biofiltration, rendering the biogas suitable for catalytic reforming into a mixture of CO and H-2 syngas that was then applied for the generation of electricity using a solid oxide fuel cell or for the chemical synthesis of methanol. The biogas was anaerobically produced in a 2 m(3) bioreactor at 35 degrees C for 2 years using restaurant food waste from Korea Advanced Institute of Science and Technology (KAIST), and the concentration of H2S in the biogas ranged from 612 to 1,500 ppmv (Avg. 1,060 ppmv). Two immobilized cell bioreactors 0.2 and 8.5 L in volume were loaded with aerobic sludge and used to study characteristics of H2S removal from biogas. At a retention time of 400 sec, the removal efficiency of H2S was over 99% following initial stabilization for 7 days in the 8.5 L bioreactor installed at the on-site biogas facility. The maximum rate of H2S removal in this study was 359 g-H2S/m(3)/h with an average mass loading rate of 14.7 g-H2S/m 3/h (kinetic analysis: V-m = 842.6 g-H2S/m(3)/h and K-s = 2.2 mg/L). Therefore, purified biogas with a negligible concentration H2S was efficiently reformed to syngas. This study demonstrates the feasibility of biogas purification as a part of high-quality syngas production.