Anaerobic treatment of industrial wastewater produces not only useful methane but also highly toxic hydrogen sulfide gas. Especially for the wastewater containing high concentration sulfate, such as wastewater from molasses, natural rubber, and brewery, high concentration of hydrogen sulfide is produced in anaerobic treatment. Usually, hydrogen sulfide is chemically removed from biogas. But there are several problematic issues for chemical desulfurization such as chemical cost or disposal of waste. Compared to chemical desulfurization, biological desulfurization could remove hydrogen sulfide in lower cost, however the process produces sulfur-containing slurry.
Denitrification using sulfur compounds is an alternative to heterotrophic denitrification, and the process is suitable for wastewaters with high concentration of nitrate and low concentration of organic matter. Thus in this study, combined system of biological desulfurization and sulfur denitrification using sulfur-containing slurry is developing.