Culture Condition And Extracellular Polymeric Of Thiobacillus Ferroxidans Of Removal Sulfur Dioxide In Bio-trickling Filter

Air pollution is becoming one of the environmental issues of concern to everyone,so that the legislation is increasing to control the emission of pollutants. In recent years,biological techniques were constantly applied to control the discharge of pollutants,because they eliminate the drawbacks of a variety of traditional chemical and physicalmethods. Different exhaust gas requires different approaches to achieve the best andcontinued removing efficiency. The biological method is economic and environmentallyfriendly solution of variety of emissions. This study focuses on the microbial removal ofSO₂.It’s mainly content including separating Thiobacillus ferrooxidans, optimizing theconditions of T.f and removing SO₂gas in bio-trickling filter using the activated carbon.Thiobacillus ferrooxidans screened from Sludge and soil. The growth cycle of T.fis about35hours, which is shorter than similar studies of bacteria growth cycle,20hours to reach the logarithmic growth phase. Fe²⁺ion oxidation characteristics ofThiobacillus ferrooxidans is initial9g/L Fe²⁺ion completely oxidation during28hours.Identifiing the main component of the precipitates is [NH₄Fe₃（SO₄）₂（OH）₆] and[KFe₃（SO₄）₂（OH）₆]. The result of the four levels of the four factors Orthogonal testwere30℃, pH2.0, inoculum size20%, the liquid volume of50（250ml flask）. Affectingthe primary and secondary factors was inoculum size> Temperature> liquid volume ofpH.According to the mechanism of precipitation generation,studied different Nitrogensource and the cation of precipitation during T. f growing for reducing the precipitationthen got new medium.The best nitrogen source is Diammonium phosphate,concentration is1.5g/L. Diammonium phosphate replace of Ammonium sulfate and potassium hydrogen phosphate. Ferrous concentration is13.5g/L.In the new culturecondition, germ growth with higher oxidation activity and less precipitation isConducive to industrial applications.Imobilization in activated carbonthe bio-trickling filter included culitiving internaland external of filter tower.After the replacement of three medium biomass reached amaximum of35.9mg vss/g. Biotrickling filter operating conditions follows: inlet massconcentration of SO₂<2000mg/m³, the amount of Spray168L²72L/m³（fill）· h, thetime of gas residence90, the range of pH1.2¹.5. Further study of the mechanism ofremoving SO₂gas in the trickling filter is on the EPS of Acidithiobacillus ferrooxidans.Exploring the EPS extraction method, EDTA extraction of polysaccharides and proteincontent is respectively0.63g/L,0.53g/L,and the method is minimum damage of the cells.Surface biomass of activated carbon and EPS have a larger correlation, indicating thatthe EPS is conducive to the growth of bacteria of the filler surface, but also conduciveto the trickling filter purification of SO₂.