Study on the Sulfide Biological Oxidation and Recycle Elementary Sulfur in Biological Flue Gas Desulphurization Process

Absorption-biological flue gas desulphurization process is a cost-effective and widely applied SO2 removal technology.It is can be divided into SO2-absorption,anaerobic reduction and aerobic oxidation,and the third zone was focused in this article.The biological oxidation process of sulfide to sulfur with colorless sulfur bacteria was studied in an internal circulating bio-fluidized bed reactor(effective volume 45L) with the sulfide effluent from anaerobic zone as the influent.After 28 days of operation,the organic loading rate reached over 3.73 kgCOD/(m3 d) and 1.09 kgS2 /(m3 d) for the sulfide loading rate.The removal efficiency of organic and sulfide were more than 70% and 85% respectively while the maximum yield of sulfur was 75% approximately.Moreover,the microscopic photographs and X-ray diffraction analysis showed that there were sulfur granules and membranaceous sulfur in effluent water.In addition,two efficiency factors including hydraulic remain time and the air aeration quantity were inspected.The investigation demonstrated that the optimum hydraulic remain time was 8h under the influent concentration of S2 and organic respectively for 200 mg/L and 800 mg/L,and the best treatment effect of aeration was obtained at 60～90 L/h.