Application And Optimization Of Microbial Remediation Technology In Polycyclic Aromatic Hydrocarbon Contaminated Sites

With the development of urbanization and industrialization and the adjustment of industrial layout,the relocation of urban industrial plants has become a development trend,and the pollution of industrial waste sites is serious.This study takes Huangshi Dongfanghong steel Plant relocation site in Hubei Province as an example.Through sampling and analysis,the field soil pollution situation is detected,the field pollution type is evaluated,the high-efficient degradation soil microorganism is screened,and the application and optimization of contaminated soil remediation measures in various projects is proposed,and then put forward a set of economical and feasible remediation methods.The results can provide data support and technical support for the microbial remediation scheme of similar polycyclic aromatic hydrocarbon site pollution.The main conclusions are as follows:(1)The pollution degree of the abandoned site of Dongfanghong steel plant in Huangshi City,Hubei Province was evaluated.The soil of the study site belongs to the level of mild PAH pollution.The heavy metals measured in the soil of the site do not exceed the class II land standard of construction land,while only the content of benzo[a]pyrene(19mg/kg)in 16 PAHs exceeds the standard.(2)Two strains of PAHs degrading bacteria were successfully screened.Seven strains of degrading bacteria were screened from soil,among which strains xbh02 and xbh03 had the highest degradation rate.They were identified as Rhodococcus and pseudoarthrobacter oxydans by 16S rDNA;The optimum growth temperature of the two strains was 30℃,the optimum pH was 7,and the best carbon source was glucose.(3)The remediation effect of indigenous degrading bacteria screened from soil on benzo[a]pyrene,as well as the synergistic effect of oxygenation rate,surfactant type,alien Pseudomonas aeruginosa and indigenous bacteria on the degradation of benzo[a]pyrene were explored.The degradation efficiencies of benzo[a]pyrene were 47.61%,55.56%,62.57%and 67.33%respectively;Batch application of 400 m L bacterial solution increased the degradation efficiency by about 2%compared with one-time application.(4)The remediation scheme of simulated polluted site and its economic feasibility were optimized and evaluated.Among the four combined remediation modes,the combination of"Tween 80+mixed bacterial solution of Pseudomonas aeruginosa and screened strains"is the most economical and effective to meet the requirements of contaminated sites.The degradation rate of site soil can reach 77.50%after 4 weeks of simulated remediation,and the remediation cost is 140 yuan/m~3.Compared with other commonly used remediation technologies,it is economical,reasonable and feasible.