Research On The Degradation Characteristics Of A Nitrobenzene Cold-adapted Bacteria

Nitrobenzene (nitrobenzene, shortened form NB) is one of important basicchemical raw material and has the stable chemical properties, high toxicity, andbiological accumulation. Which belongs to ‘three causes matter’. However, thedemand of nitrobenzene show ascendant trend with the chemical industrydevelopment, thus cause the serious problems of environmental pollution with theemission. The common technology includes physical methods, chemistry methodsand biological methods in removal nitrobenzene. The biological methods can degradepollutants greatly with low cost and simple operation. In recent years, microbialdegradation in nitrobenzene wastewater treatment and pollution environmentalrestoration have obvious advantages. It is significant to screen bacterium that caneffectively degenerate nitrobenzene and apply it to the actual treatment of wastewatercontaining nitrobenzene will have very important significance.In this paper, making an effective redomestication of the low-temperaturedegradation of nitrobenzene of strains cc-2which is kept in laboratory. To researchthe growth and degradation under different the nitrobenzene initial concentrationwhich shows that the strain with high degrading ability, and the growth curve isdrawn. According to physiological and biochemical characteristics and16SrDNA, thebacterium cc-2is identified as Acinetobacter baumannii. The study on degradationcharacteristics of cc-2shows that the optimum conditions for the bacteria are15℃,pH7,140r/min and inoculation amount10%. When the initial concentration ofnitrobenzene less than100mg/L, the degradation rate is greater than85%in48h. Thedegradation rate is60.53%in48h when the nitrobenzene concentration is200mg/L.The maximum tolerated concentration of cc-2to nitrobenzene is400mg/L. Exploreways to strain degradation of nitrobenzene, NH4+but not detected in detection due tothe degradation process of a NO2-, inference may be aerobic part of the reductionpathway.Effects of nitrobenzene biodegradation by cc-2immobilized on granular activated carbon is studied. To research the granular activated carbon adsorptionisotherms of nitrobenzene and which meet Freulndlich empirical formula and theoptimum dosage is5mg/mL of granular activated carbon. The biodegradation time isshortened for200mg/L nitrobenzene with biological activated carbon present whichcompares with the bacteria before immobilized. But for400mg/L nitrobenzene couldnot been directly biotransformed by the bacteria due to the intense inhibition.However, nitrobenzene at the same concentration is biodegraded in46h by thebiological activated carbon when the condition is15℃, pH7,140r/min. Activatedcarbon is regenerated by microbial action.Studying on the degradation kinetics of cc-2stains of nitrobenzene in theoptimal growth condition. The results indicate that when the initial concentration ofnitrobenzene less than100mg/L, it is in accordance with the zero order kinetics, thecorrelation coefficient is0.981-0.995. When the initial concentration of nitrobenzenegreater than100mg/L, the degradation process accord with the Andrews models. Thekinetic parameters are: μmax=2.059/h, Ks=54.682mg/L, Ki=64.138mg/L.