Characteristic And Kinetic Study Of4-chlorophenol And Phenol Biodegradation By Brevibacillus Borstelensis

Chlorophenols were polyphenols which indefinite number of hydrogenatoms on phenol rings were replaced by chlorine atoms. As an integral part ofindustrial material, chlorophenols is widely used in chemical industy, pharmacy,dye, paper manufacturing industry, pesticide industry and preservative agents,etc. They are a long stay in the environment, can cause serious damage to humanbody health and ecological environment. So it is rated as a priority pollutant bythe US Environmental Protection Agency because of this great ubiquity.With the known toxicological effects of correlate chlorinated phenols andtheir derivatives, as well as their environmental contamination with bioaccum-ulation, study on the treatment of chlorophenols wastewater is the present focusand challenge in research area of environment science and engineering fieldsworldwide. Compared with other kind of methods, biological method is better in lowcost, high efficiency, energy saving, easy operation, at the same time, no secondpollution. In which, the efficient chlorophenol degradation bacterium prominentin biodegradability and tolerance, so it superior to degrade high concentrationchlorophenol. Therefore, screened the efficient bacterium which degrade chloro-phenol in aerobic condition, studied its biodegration characteristics, applied intothe chlorine phenol wastewater pollution treatment had an important theoreticaland guiding significance.In this experiment,4-chlorophenol has been investigated. The bacteria,named Brevibacillus borstelensis, which has been separated from the activatesludge was used through out our work. Researches of substrates biodegradationwere carried out under different condition and the optimal temperature and pHfor4-chlorophenol degradation were specified as:30℃and7.0, respectively andunder which, the bacteria could utilize4-chlorophenol as the sole carbeon andenergy source, the maximum biodegradation ability of this for4-chlorophenolwas300mg/L, The strain could completely degrade200mg/L,250mg/L and300mg/L4-chlorophenol within48h,63h and84h respectively. The enzymeassay indicited that chlorocatechol1,2-dioxygenase was generated during thedegradation process, so the degradation mechanism of4-chlorophenol followedthe pathway of ortho fission.Kinetics study was performed using4-chlorophenol as the sole carbon andenergy, the initial4-chlorophenol concentration were varied from0to300mg/L. Haldane type substrate inhibit model could able to simulate the cell growthon4-chlorophenol. At the same time, with the analysis of the Origin software,the data obtained completed the nonlinear fitting, the model could exactlyforetell the dynamic behavior of cell growth. Parameters were obtained asμmax=0.185h-1, Ks=30.45mg/L, Ki=127.62mg/L with correlation coefficientR2=0.98.As the composition of the real wastewaters were always very complicated,deficient of single substrate research was obvious. In view of this, we took adeep examination of Alcaligenes faecalis growth as well as substrates interactionin dual mixture. Investigation was conducted within a widearange of initialsubstrates concentration (4-chlorophenol0-80mg/L and phenol0-1400mg/L).In the phenol/4-chlorophenol dual substrate degradation system, the existence of4-chlorophenol inhibited the biodegradation of phenol;1400mg/L phenol in thepresence of4-chlorophenol was degraded within a longer time period thanphenol alone. The strain preferably utilize phenol as carbrton and energy sourceand most4-chlorophenol was degraded after phenol was completely consumed.On the other hand, the presence of low-concentration phenol with150-300mg/Lsupplied a carbon and energyrsource for Brevibacillus borstelensis in the earlyphase of biodegradation and accelerated the assimilation of4-chlorophenol, wh-ich resulted in that300mg/L4-chlorophenol was degraded within less time thanthat without phenol. The degradation rate of4-chlorophenol was fastest whenthe concentration of phenol was200mg/L. However, phenol higher than 300mg/L inhibited the biodegradation of4-chlorophenol. The kinetics equationpresented by Abuhamed could accurately depict cell growth in dual substratebiodegradation system and the interrelate parameters were： I1,2=1.47andI2,1=2.56with correlation coefficient R2=0.95.