Study On Nitrobenzene Degradation Coupled To Bacterial Dissimilatory Reduction Of Iron Oxides Using Oil-emulsion As Electron Donor

As the development of electro-organic synthesis industry, the nitrobenzenepollution of groundwater and surface water is becoming more and more serious.Nitrobenzene is biological toxic and persistent material, and has a great influence onhuman life and health. So the remediation of nitrobenzene pollution is becoming moreand more important. Recent year, the studies on nitrobenzene degradation coupledbacterial dissimilatory reduction of iron oxides have attract much attention.The usual electron donors for the dissimilatory iron reduction aremonosaccharide and organic acid, which are soluble substrates. In the source area,these substrates will be rapidly depleted which result in regular injection of thesubstrate. However, oil-emulsion provide an effective, long-lasting and low costalternative for the anaerobic bioremediation process.In this study, a series of researches have been designed to evaluate theperformance of oil-emulsion for the biodegradation of nitrobenzene coupled to thedissimilatory iron reduction. The results indicated that:(1) The oil-emulsion made in the lab is the best when polysorbate-80is usedas emulsifier, the proportion of soybean oil and polysorbate-80is20:1, andsupersonic shock for30minute; Either using goethite or hematite as electronaccepter, oil-emulsion can provide as electron donor for the reaction of ironreduction and nitrobenzene degradation, and1g/L is the optimum for the system.(2) In the goethite or hematite system, although the initial iron reduction andnitrobenzene degradation efficiency of oil emulsion is lower than acetate andglucose, but it can provide longer-term electron for the reaction and get a goodnitrobenzene removal rate(about70%); So oil-emulsion can be served as anpersistent, inexpensive an effective substrate for the dissimilatory iron reductionand nitrobenzene biodegradation.(3) In the reaction system, nitrobenzene biodegradation efficiency is thehighest when3ml goethite or hematite is added and the efficiency is67%and44.69% separately; Goethite is more appropriate for oil emulsion system than goethite; Oilemulsion concentration has a great influence on the nitrobenzene biodegradation,and1g/L is the optimum concentration for the reaction; Nitrobenzene influences theactivity of the microorganism so as the nitrobenzene concentration gets higher thenitrobenzene biodegradation efficiency of the system gets lower, and100mg/L isthe optimum; When the nitrobenzene concentration is100mg/L, goethite additionis3ml and oil emulsion is1g/L, a highest nitrobenzene removal efficiency can beget.(4) Add glucose (oil-emulsion: glucose is20:1) to the oil emulsion-goethitesystem can improve nitrobenzene removal efficiency to80%and the degradationrate of nitrobenzene goes up20%; In the simulation experiment, oil-emulsion canalso provide long-term electron for the iron reduction and nitrobenzenebio-degradation; The nitrobenzene degradation efficiency of the oilemulsion-glucose system is up to71.21%; But the addation of50mg/L glucosecannot improve the reaction rate in the simulation system.