Biological Sulfur Reduction To Generate H2S As a Reducing Agent To Achieve Simultaneous Catalytic Removal of SO2 and NO and Sulfur Recovery from Flue Gas

The conventional flue gas treatment technologies require high capital investments and chemical costs, which limit their application in industrial sectors. This study developed a sulfur-cycling technology to integrate sulfide production by biological sulfur reduction and simultaneous catalytic desulfurization and denitrification with H2S (H2S-SCDD) for flue gas treatment and sulfur recovery. In a packed bed reactor, high-rate sulfide production (1.63 ± 0.16 kg S/m3-d) from biological sulfur reduction was achieved using organics in wastewater as electron donors at pH around 5.8. 93% of sulfide in wastewater was stripped out as H2Sg, which can be a low-cost reducing agent in the H2S-SCDD process. Over 90% of both SO2 and NO were removed by the H2S-SCDD process under the test conditions, resulting in the formation of sulfur. 88% of the input S (H2Sg and SO2) were recovered as octasulfur with high purity. Besides partial recycling to produce biogenic sulfide, excessive sulfur can be obtained as a sellable product. The integrated sulfur-cycling technology is a chemical-saving and even profitable solution to the flue gas treatment in industrial sectors with wastewater available.