Research On The Performances Of Sulfur Autotrophic Denitrifying Bacteria For Nitrate And Thiosulfate Removal

Based on the deficiency of complex absorption denitration process and the biological flue gas desulfurization. a new idea that biological reduction combined with chemical absorption is proposed for synchronous desulfurization and denitration by our group. As a part of the subject, the growth and the characteristics of sulfur autotrophic denitrifying bacteria were investigated during the sulfur autotrophic denitrifying process, the reaction process of autotrophic Fe(II)EDTA-NO removal was studied under anaerobic conditions, and product of Fe(II)EDTA-NO was monitored.In the experiment, sulfur autotrophic denitrifying bacteria, Paracoccus versutus LYM.(GenBank JQ328185), was isolated from the seabed sediment. It was a sphere-and short rod-shaped, gram-positive, and facultative bacterium. When the nitrate, nitrite, and NO existed, the bacterium could grow and reduce them in anaerobic conditions and the end production was N2. The optimal conditions for nitrate reduction and sulfur oxidation were determined to be as follows:the removal amount of sulfate was largest when the inoculum quantity was800mg/L; the high removal of nitrate by strains LYM can be reached within scope of pH6.0-8.0,T20-35C; and the highest removal can be reached when pH is7and temperature is30。c.The growth and the capability of desulfurization and denitration of Thiobacillus denitrificans ATCC25259have also been examined, which was purchased from the strains preservation center. The results showed that the strains could be used for desulfurization and ’"itration after culturing for45hours. The strains could grow with organic carbon source existence. When ethanol, acetic acid sodium, sodium propionate, and sodium citrate existed, heterotrophic denitrification may be more easily happened for energy supplement. In addition the best effect of S2O32" removal efficiency could be reached to65%, when S/N was5:3.Autotrophic Fe(II)EDTA-NO reduction by strains LYM and Thiobacillus denitrificans ATCC25259was examined. The results showed that:both of the strains could reduce Fe(II)EDTA-NO autotrophicly, and the product was mainly N2, the middle product was N2O. In the process, strains LYM can use Fe(II)EDTA as electron donor to autotrophic reducing Fe(II)EDTA-NO. And Thiobacillus denitrificans could be realized with Fe(II)EDTA-NO as electron accepter and S2O32-as electron donor to achieve the goal of simultaneous desulfurization and denitration. And this is the first report about reducing Fe(II) EDTA-NO in the process of sulfur autotrophic.