Ethanol Domestication Of Sulfate Reducing Bacteria Dealing With High Concentration Of Experimental Study On Chromium Containing Waste Water

Wide using of the chromium compounds in various fields,it will produce a lot of high concentration of wastewater containing chromiu.With the favourable effect of microorganisms,its simple operation and no secondary pollution,we used microbiological method to deal with wastewater containing Cr?VI?.In this paper with high concentration of chromium containing wastewater as the research object,to foster domesticated strains of chromium as the research target,chromium reduction for efficient strain processing studies the high concentration waste liquid containing chromium.The main findings are as follows:?1?The sludge was enriched by using new carbon source ethanol,and When the strains are multiplied,the ability of bacteria to resist chromium is tamed.Then,the screened strains were purified and separated by dilution coating and sandwich culture and was named"bacteria CR-1".Cell staining and physiological and biochemical experiments were carried out to identify the genus CR-1 of Desulfovibrio.?2?Optimum conditions for treatment of wastewater containing Cr?VI?by strain CR-1:The temperature is 30?-40?.pH is about 7.The ratio of bacteria to waste is 1:5,and the best carbon source is alcohol.Other heavy metal ions on degrading strains to treat containing chromium inhibited wastewater respectively:Cd²⁺>Zn²⁺>Pb²⁺.The sulfate ion concentration should be controlled at 2000mg/l-3000mg/l.Three main factors including the temperature,pH and bacteria reject ratio affecting bacteria to reduct chromium were regressed.Using Levenberg-Marquardt and general global optimization method,the optimum solution is as follows:when the temperature is 35,pH is 7.1,and the ratio of bacteria to waste is 1:4,the theoretical value of chromium reduction rate of this strain can reach 99.9%.?3?The mechanism of the treatment of Cr?VI?with bacterial strain CR-1 can be seen:most of the Cr?VI?removal is due to the accumulation of bacteria H₂S on the reduction of Cr?VI?,while the remaining part of the removal is to rely on a small amount of H₂S produced by the bacterial reductase pathway and the growth of bacteria in waste liquid to reduce SO₄^2-.Extracellular polymers can not absorb Cr?VI?in the wastewate.?4?Kinetic experiments were carried out on an efficient chromium degrading strain CR-1,the bacterial reduction of Cr?VI?dynamic equation was obtained.According to the estimation equation for degrading strain CR-1,maximum reduction for Cr?VI?was201.98mg/l,while the actual within 24 hours of Cr?VI?reduction was 147.4mg/l.The maximum reduction amount estimated by kinetic equation was only 54.58mg/l difference with the actual amount of reduction,indicating that the strain CR-1 had a general ability to reduce chromium.?5?The dynamic hanging column dynamic test of high chromium degrading strain CR-1 was carried out,and a dynamic column of biofilm and a blank column without film were set up with zeolite,quartz sand and elastic fiber as fillers.The results showed that the solution in the reaction process of pH did not change too much,and three hanging film dynamic column on the six chromium removal rate was above 92%.Using elastic fiber as the dynamic column packing of Cr?VI?the treatment was better.Quartz sand and elastic fiber hanging film had little effect on the removal of total chromium,and the removal of total chromium by zeolite as a dynamic column for hanging membrane material reached the puncture point at fourth days and reached saturation point in fifteenth days.