The Research Of Immobilized Phenol Degrading Bacteria And Its Remediation

Phenol is a highly toxic substances, mainly coming from various industrial wastewater.Phenolic compoundas can pollute water, do farm to crops and even heavily threat humanhealth when the wastewater which containing phenol was direct emission and not be treatedstrictly. Microorganism that can effectively degrade phenolic compound had been isolatedfrom natural environment, they can be poured into waste water treat system and obviouslyenhance the effect, therefore, they have extroordinary potential in bioremediation. In order toimprove low microbial resistance to environment changes, shorten the processing time,increased bacteria stability and activity, immobilized method was required to improve themicrobial degradation.This research aimed to screen strains with high phenol degradating capacity from soiland investigated the fit conditions of degrading phenol. Adsorption the Rhodococcus ad049on bamboo carbon. The immobilized bacteria was used to remedy phenol contaminated soilby pot exeperment, and investigated the soil enzyme activities, phenol concentrations andmicrobial communities during the soil remediation process. The research results were asfollows:1. Identification and characteristics of phenol degrading bacteriaA bacterium strain, which prove to be highly effective in phenol degrading, was isolatedfrom soil contaminated with oil in Jingbian oilfield of Northern Shaanxi by using enrichmentculture method with phenol as a sole carbon source. The bacterium was named ad049andidentified as Rhodococcus pyridinovorans on the basis of the morphological characterizations,physiological and biochemical identification, and alignment analysis of the16S rDNAsequence. Effects of inoculation quantity of ad049, pH, temperature, and concentration ofphenol as a substrate on bacterial growth and the efficiency of ad049on phenol degradationwere also investigated by shaker culture method, and dehydrogenase and catecholdioxygenase were determined as well. Results showed that the ad049had a strongbiodegradation capability for phenol. It degraded99%of the phenol in a concentration of1000mg/L in24hours under the incubating condition of30℃, pH8, and5%of ad049inoculation. The degradation process could be described with zero order kinetics equation with the k0and R2values of41.51and0.96, respectively. The degradation of phenol by ad049might be achieved largely by1,2-dioxygenase for ortho ring opening of benzene, and partlyby catechol2,3-dioxygenase for meta-cleavage.2. Study of immobilized degrading phenol bacteria on bamboo carbonAdsorption a phenol degrading bacteria Rhodococcus ad049on bamboo carbon, whichprove to be highly effective in phenol degrading, was isolated from soil contaminated with oilin Jingbian oilfield of Northern Shaanxi by using enrichment culture method with phenol as asole carbon source. The optimal absorption conditions was investigated by orthogonal test.Various factors and their influences on phenol degradation of immobilized cells were studied,including temperature, pH and initial phenol concentrations. The reusability of immobilizedcells and the kinetics of phenol degrading were also investigated. The results showed that theoptimal ad049immobilized on bamboo carbon condition is that1.5g bamboo carbon qualityand3mL inoculation absorbed for24h. The immobilized cells revealed high phenoldegradation rate than free cells under the various conditions such as temperature20~45℃，pH5~13and initial phenol concentrations1000~1500mg/L, since bamboo carbon as a carrieralleviated external environment conditions to influence on cells. The complete degradationtime decreased from28h (free cells) to20h (immobilized cells) under the condition of aphenol concentration of1000mg/L. The degradation of phenol still maintained above98%after the twentieth reuse under the condition of a phenol concentration of1500mg/L, itshowed that the immobilized cells have excellent reusability. Furthermore, the degradationratio of phenol of both free cells and immobilized cells were found to fit well withzero-order model.3. The remediation of phenol contaminated soil by immobilized bacteriaA soil remediation culture experiment with four treatments was conducted to investigateeffects of soil remediation with bacteria immobilized with bamboo charcoal on activities ofsoil enzymes and function diversities of soil microbe communities. It revealed that on thetwentieth incubation day, the phenol degradation rate of added immobilized bacteria treatmentwas the highest reaching90.25%, the not added bacteria and added free bacteria treatmentswere49.71%and28.37%lower than that of added immobilized bacteria treatment; the phenoladditions promoted the dehydrogenase activities, inhibited the urease activities and firstinhibited and then promoted the polyphenol oxidase activities. Biolog analysis showed thatthe AWCD of not added bacteria, added free bacteria and added immobilized bacteriatreatments were34.62%,19.98%and11.01%lower than that of control treatment,respectively; the Shannon index, McIntosh index and McIntosh evenness index of controltreatment were all significantly higher than those of three treamnets, and the Simpson index of control treatment was lower than those of three treamnets, and not added bacteria treatmentwas highest; and compared with control treatment, the other three treatments exploited aminoacids, polyphenols and polyamines at an increased rate and carbohydrates and carbolic acidsat a decreased rates. Principal component analysis revealed that T1and T2evidently modifiedcarbon source exploitations of soil microbes. Analysis of correlation showed that the enzymeactivity, microbe activity and community diversity of T3did not significantly differ fromthose of CK（P＞0.05）, indicating that remedied with the immobilized bacteria, the phenolcontaminated soil could recover its enzyme activity and community diversity to its levelsbefore polluted.