Study On Mutagenic Selection Of Ferromanganese-oxidation Bacteria To Be Used In Pyrolusite Flue Gas Desulphurization And Oxidation Kinetics Of Fe～(2+) And Mn～(2+) By The Bacteria

Combination of pyrolusite and ferromanganese-oxidation bacteria to desulphurize flue gas is a new method. In the system, ferromanganese-oxidation bacteria are applied to oxidize and regenerate Fe~2+ and Mn~2+ in order to renew the catalyzers, MnO2 and Fe2O3, and maintain the desulphurization ability of the pyrolusite. At the same time, Thiobaciiius ferrooxidans can directly oxidize SO2, which further improve desulphurization efficiency of the whole system. But the oxidation efficiency of Mn~2+ and Fe~2+ by ferromanganese-oxidation bacteria greatly depends on the bacterial survival environment and the low activity limited their application to the practical desulphurization process. Hence, selecting ferromanganese-oxidation bacteria which has high oxidation efficiency to Mn2+ and Fe2+ and can live in a wider pH range is the key point to the desulphurization efficiency of the combination system of pyrolusite and ferromanganese-oxidation bacteria.In this paper, mutagenic selection of ferromanganese-oxidation bacteria by ultraviolet radiation was carried out in order to obtain bacteria of high efficiency. Oxidation process of Fe2+, Mn2+ and SO32" by ferromanganese-oxidation bacteria was studied and the kinetics parameter was obtained. Meanwhile, changes of dissolved oxygen during the oxidation process were investigated.After mutagenic selection of ferromanganese-oxidation bacteria by ultraviolet radiation, those of high efficiency, LT 5.0 and ML1 were obtained. The study results indicated that at 30°C, agitation rate 150 r/min, concentration of Fe2+ 6.5 mg/L, initial pH=2.5^ 4. 5, Fe2+ will be totally oxidized in 24h> 24h, 30h respectively. At pH=2.5. Fe2+ concentration ranging from 3.5g/L to 15.5g/L, oxidation of Fe2+ by Thiobaciiius ferrooxidans followed first-order kinetics with the velocity constant equal to 0.0468~0.0615h"'. In the absence of Fe2+, oxidation rate of SO32 by Thiobaciiius ferrooxidans is better than that of without bacteria. In the presence of Fe2+, direct oxidation to SO32" by the bacteria is not obvious. At 30°C, agitation rate 120 r/min, concentration of Mn2+ 140 mg/L, initial pH=^ 5, 6, 7, 57.36% ^ 65.58 %, 68.78 % ? 74.45 % of Mn2+can be oxidized respectively by LM1. At pH=4, Mn2+ concentration ranging from 70mg/L to 500mg/L, oxidation of Mn2+ by manganese-oxidation bacteria followed first-order kinetics with the velocity constant equal to 0.012~0.0275h~!. At pH=6 and Mn2+concentration ranging from 60mg/L to 290mg/L, oxidation of Mn2+ also followed first-order kinetics with the velocity constant equal to 0.006~0.0145h~1.These study results can offer important basic data for research of combination desulphurization system of pyrolusite and ferromanganese-oxidation bacteria. And valuable references will be provided for further study on fundamental theory of microorganism to be used in desulphurization.