Coupled Attenuation Of Nitrobenzene By Bacterial Dissimilatory Reduction Of Iron Oxides

Fe（Ⅲ） contained in iron oxides is reduced to Fe（Ⅱ）,and then the Fe（Ⅱ）adsorbs to iron oxides, which named dissimilatory iron reduction.In thisprocess, stabilized nitrobenzene could be reduced to aniline,which could bedegradated thoroughly to carben dioxide and water. And this process is acyclic biochemical reaction, organics as electron doner, Fe（Ⅲ） is reduced toFe（Ⅱ） by iron reducing microorganism, and Fe（Ⅱ） is oxided to Fe（Ⅲ） bynitrobenzene. This study bases on esisting research about iron dissimilatoryreduction, concentrates on the availability and impacts of nitrobenzene,sreduction by dissimilatory iron reduction.The availability option, shows by the concentrations of nitrobenzene andaniline, the concentrations of Fe（Ⅱ）,and ORP changes; The impacts option,shows by components joined in dissimilatory iron reduction, for examples,electron doner, electron acceptor, iron reducing microorganism andnitrobenzene. The results show that ammonium acetate is the most suitelectron doner in ammonium acetate, ammonium citrate and glucose, becauseiron reduction microorganism show up the best tendency, and the reductionrate of nitrobenzene is high at78.5%;Nitrobenzene could be as carbon sourceof iron dissimilatory microoganism at low concentration such as below150mg/L, the biomass decrease when the concentration of nitrobenzene between150-400mg/L, and once to600mg/L, the iron reducing microorganism almostdeath; Goethite and hematite are the most iron oxides in underground, andgoethite is a better electron accepter than hematite, and0.3mg/L is a suitableconcentration;4×10⁸cells/mL is the suitable concentration of ironmicroorganism.Electron shuttles such as humic acid, anthraquinone and riboflavin aremixed in the coupled attenuation system.The results show that humic acid isthe most suitable electron shuttle, nitrobenzene attenuation rate is88.8%inthis system which humic acid mixed. Anthraquinone increase the attenuation rate at a low percent.And at last, riboflavin hinder the attenuation ofniteobenzene.Simulated column is needed for researching the application possibility ofdissimilatory iron reduction in groundwater. So we have three column, Aadded with HgCl₂of1000mg/L, B added with iron reducing microorganism,and C. The results show that dissimilatory iron reduction could be used insimulated system of groundwater when the concentretion of nitrobenzenebelow200mg/L. Physical attenuation, pannonibacter phragmitetus attenuationand iron reducing microorganism attenuation account for14.9%,23.8%,61.3%respectively.