A novel biological treatment process for removing hydrogen sulfide from anaerobic biogas using a bio-scrubber has been developed. The treatment process is composed of a gas/liquid contact tower and an aeration tank. The biogas from an anaerobic wastewater treatment process is introduced into a multiple-bubble-tray contact tower (bio-scrubber) and scrubbed with activated sludge liquor from an aeration tank. The sludge liquor containing sulfides is then returned to the aeration tank, where the sulfide is oxidized to sulfate by sulfur-oxidizing bacteria such as Thiobacillus. The contact tower is designed to be air tight in order to prevent air from mixing into the biogas used as a fuel. A simulation model was developed to calculate effluent gas concentrations from the contact tower, incorporating input parameters such as influent hydrogen sulfide concentrations, gas flow rates, and gas/liquid ratios. Using the simulation model, design criteria were calculated and a full-scale plant for treating biogas from a UASB process for potato processing wastewater was constructed. The data shows that the hydrogen sulfide in the biogas was effectively reduced from 2,000 ppm to less than 20 ppm.

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