Performance evaluation and effect of circulation rate in a bio-desulfurization process aerated by biogas circulation

摘要

The biological desulfurization of biogas using a bubble column reactor was investigated in a continuous experiment. Aeration by rapid biogas recirculation between the digester and the biological desulfurization reactor was used to stimulate the gas-liquid mass transfer of H2S. A positive correlation between the biogas circulation rate and H2S removal rate was observed, with 93% H2S removal efficiency and a 1520 L/L-culture/d recirculation rate at a 500 L/L-culture/d biogas loading rate. Moreover, the increase in the biogas circulation rate stimulated the O2 mass transfer, eventually translating into an increase in sulfate production from the oxidation of H2S. Throughout the continuous experiment, the bubble column reactor retained sufficient levels of sulfide-oxidizing bacteria, including Sulfurimonas denitrificans-velated bacteria and Halothiobacillus neapolitanus-related bacteria. A comparison of the results of the continuous experiment and batch tests suggests that the gasliquid mass transfer rate of H2S was the ratelimiting step in the biological desulfurization using the bubble column process, indicating that the mass transfer efficiency of H2S needs to be improved to enhance the desulfurization performance.