Research On Electro-biofilm Remediation Technology Petroleum-contaminated Sediments

As a main marine organic pollutant,Petroleum has caused serious pollution of marine sediments due to its easily absorbable nature.Combined with the advantages of electric remediation and microbial remediation,the paper carried out the research on Electric-biofilm remediation technology petroleum-contaminated sediments.In this paper,the simulated petroleum-contaminated sediment was prepared with 0# diesel as the target pollutant.Three high efficient petroleum degrading bacteria were domesticated and selected from the sediments of Qinhuangdao Port.The biofilm was prepared with the thtree high efficient petroleum degrading bacteria and the activated carbon as a carrier.The electric-biofilm composite remediation system was constructed,and the electric-bioremediation conditions were optimized.The effects of the enhanced remediation measures such as the addition of nutrients and surfactants on the petroleum removal rates in sediments were also studied.The results were shown as follows:Three high-efficiency petroleum-degrading bacteria were identified as Acinetobacter sp,Stenotrophomonas sp and Exiguobacterium sp through physiological and biochemical identification and 16 SrDNA molecular biological identification.Environmental conditions such as temperature,pH and initial petroleum concentration could affect the degradation performance of high efficient petroleum-degrading bacteria.When the initial petroleum concentration was in the range of 375mg/L to 6000mg/L,this factor had little effect on the degradation performance of high-efficiency petroleum-degrading bacteria.When the pH is 7-8,the degradation performance of petroleum-degrading bacteria was better,and the removal rate of petroleum was higher.The optimal pH value is 8.The proper amount of nutrients helped to improve the degradation performance of petroleum-degrading bacteria.The optimal N: P ratio was 5:1.The petroleum-degrading bacteria worked well between 25-35? and the optimum temperature was 30?.The exchange electrode method helped to stabilize the pH,oxidation-reduction potential and temperature in the sedimental environment,so as to facilitate the growth of high efficient petroleum-degrading bacteria and the degradation of petroleum in the sediment.The optimal repairing conditions of the electric-biofilm remediation system were determined as follows: voltage gradient was 0.5v/cm,electrode switching period was 3h,and the biofilm was placed in the S3 unit.Under the optimal repairing condition,the removal rate of petroleum in the sediment could reach 44.2% after 7 days of remediation.Adding appropriate amounts of nutrients and surfactants could significantly increase the rate of petroleum degradation in sediments.When the N: P ratio was 5:1,the removal rate of petroleum in the sediment reached 57.2%,which was 13% higher than that in the experimental group without nutrients.The removal rate of petroleum in sediments was as high as 68.6% with the addition of rhamnolipid.The better enhanced remediation occurred because the surfactants could not only strengthen the biodegradation mechanism,but also enhance the electrodialysis removal mechanism.Compared with the pure biodegradation products of petroleum,the contents of high-carbon-number aliphatic hydrocarbons,long-chain aliphatic hydrocarbons and polycyclic aromatic hydrocarbons in the electro-biological combined degradation products was greatly reduced,indicating that the combined electro-biological membrane remediation could improve removal rates of refractory components.