Research On Immobilization Of Polychlorinated Biphenyldegrading Consortium GYB1 And The Degradation Characteristic Of PCB 118 By Immobilized Consortium

Polychlorinated biphenyls(PCBs)are typical persistent organic pollutants in the environment.Although the production and use of PCBs have been banned for a long time,the accumulation of PCBs in water and soil environment still poses significant harm to human health and ecological environment.Microbial remediation is an effective,economical and safe technology to remediate PCBs.The searching of potential microbial resources and the screening and domestication of highly efficient degrading bacteria have become a hot spot in the field of environmental remediation recent years.Microbial immobilization technology can effectively solve the problems of poor environmental tolerance and poor degradation effect of microbial in practical application.In this paper,2,3',4,4',5-pentachlorobiphenyl(PCB 118)was selected as the typical representative of medium and high chlorinated PCBs.And the paper has studied the degradation characteristics of PCB 118 of the bacterial consortium GYB1 which was screened and domesticated from the soil of e-waste disposal site in Guiyu.Biochar and sodium alginate were used as the carriers to immobilize the consortium,and the optimal ratio of immobilized beads and the degradation advantage over suspended consortium were investigated.Finally,biochar,cells and the immobilized consortium were simultaneously used to remediation of PCB118-Cd²⁺compound contaminated soil.The remediation characteristics and mechanism of microorganism,biochar and the immobilized microorganism by biochar on PCB contaminated soil were preliminary discussed.The main research results of this paper are as follows:(1)Bacterial consortium GYB1 which was obtained by screening and acclimation from contaminated soil could efficiently metabolize PCB 118.The degradation efficiency of 0.1mg/L PCB 118 was the highest when the p H was 8,the temperature was 30?,and the bacteria dosage(wet weight)was 2 g/L.After 5 days,about 72.23%PCB 118 was degraded.By the secretion of surfactant,the hydrophobicity of the surface of the bacteria was enhanced.The consortium metabolized PCB 118 mainly through extracellular enzymes.Meanwhile,P450enzyme would be involved in the degradation process.(2)The bacterial consortium GYB1 was embedded with biochar and sodium alginate composite carrier,and the optimal ratio of biochar,sodium alginate and bacterial liquid was1.5%,2.0%and 2.0%.Compared with the free cells,the biochar immobilized bacteria beads showed a wider tolerance range of p H,temperature,pollutant concentration and Cd²⁺concentration.After stored for 90 days,the degradation efficiency of SC-GYB1 beads to 1 mg/L PCB 118 was still about 42.12%.Pseudarthrobacter and Stenotrophomonas were the dominant genera of the bacteria consortium GYB1,and the community changes of free and embedded systems were different during the removal process of PCB 118.Sphingomonas and Paenibacillus accounted for a large proportion in the immobilized system,which may have played an important role in the PCB 118 degradation process by microoganism.(3)Biochar,bacteria consortium GYB1,biochar adsorbent fixed bacteria,sodium alginate immobilized with cells(SA-GYB1)beads and sodium alginate and biochar immobilized with cells(SC-GYB1)beads were used to remediate PCB-Cd²⁺soil.Different treatments had certain effects on soil enzyme activity and p H.And SC-GYB1 embedded beads could accelerate the degradation rate of PCB 118 in soil,showing the best comprehensive remediation effect.This study discussed degradation characteristics of the PCB 118 by the efficient degradation bacteria GYB1.The community changes of degrading bacteria and the role of key microorganisms in different degradation systems were studied.The free consortium and immobilized beads were used for remediation of PCB 118 contaminated soil under Cd²⁺stress to explore the remediation mechanism of immobilized bacterial beads.The research can provide a theoretical basis for bioremediation of PCBs in polluted water bodies and contaminated soil.