Biooxidation of hydrogen sulfide to sulfur by moderate thermophilic acidophilic bacteria.

The copper industry utilizes significant amounts of sulfuric acid in its processes, generating sulfate as waste. While sulfate-reducing bacteria can remove sulfate, it produces hydrogen sulfide (H2 S) as a byproduct. This study examined the capability of a consortium consisting of Sulfobacillus thermosulfidooxidans and Sulfobacillus acidophilus to partially oxidize H2 S to S° at a temperature of 45 °C. A fixed-bed bioreactor, with glass rings as support material and sodium thiosulfate as a model electron donor, was inoculated with the consortium. Formation of biofilms was crucial to maintain the bioreactor's steady state, despite high flow rates. Afterward, the electron donor was changed to H2 S. When the bioreactor was operated continuously and with high aeration, H2 S was fully oxidized to SO4 2- . However, under conditions of low aeration and at a concentration of 0.26 g/L of H2 S, the consortium was able to oxidize H2 S to S° with a 13% yield. S° was discovered attached to the glass rings and jarosite. The results indicate that the consortium could oxidize H2 S to S° with a 13% yield under low aeration and at a concentration of 0.26 g/L of H2 S. The findings highlight the capability of a Sulfobacillus consortium to convert H2 S into S°, providing a potential solution for addressing environmental and safety issues associated with sulfate waste generated by the mining industry.