Performance evaluation and effect of biogas circulation rate of a bubble column for biological desulfurization

Biological desulfurization using a bubble column reactor was investigated in a continuous biogas treatment. Rapid biogas circulation between the digester and the bubble column for biological desulfurization 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. Moreover, the increase in the 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 reactor retained sufficient levels of sulfide-oxidizing bacteria. A comparison of the results of the continuous biogas treatment and batch tests suggests that the gas–liquid mass transfer rate of H₂S was the rate-limiting step in the biological desulfurization in the reactor, indicating that the mass transfer efficiency of H₂S needs to be improved to enhance the desulfurization performance.