Bioremediation Of Petroleum Contaminated Soil By Immobilized Microorganism With Sludge Biochar

In situ remediation technology of oil contaminated soil usually has some problems,such as poor remediation effect,easy to bring secondary pollution and so on.In this paper,a new remediation method of oil contaminated soil is proposed,which uses composted sludge as raw material to prepare composted sludge biochar,and the screened high-efficiency oil degrading bacteria are fixed on the composted sludge biochar to form immobilized microorganisms Bioremediation of petroleum contaminated soil by immobilized microorganisms from sludge and composted sludge biochar was studied.The following studies were carried out:(1)six strains of petroleum hydrocarbon degrading bacteria were selected from the reserve strains in the laboratory,and two strains C3 and c4,7 with the highest oil reducing rate were selected The degradation rate of petroleum hydrocarbon could reach 45.34% and 46.84%,which were identified as alkali producing bacteria and low G + C Gram-positive bacteria respectively.Strain C3 and C4 were compounded according to the volume ratio of 1:1to form the flora ch,and the degradation rate of petroleum hydrocarbon was 49.34%.(2)Composting sludge biochar was prepared by pyrolysis of composting sludge.The composting sludge and composting sludge biochar were characterized by SEM,bet and ICP-MS.the microorganisms(CH)were immobilized by composting sludge and composting sludge biochar respectively.The orthogonal experiment was designed by SPSS software to investigate the optimal parameters of immobilized microorganisms(CH)Compared with composting sludge,composting sludge biochar has larger specific surface area,pore volume and pore size;the fixation rate of composting sludge is only 23.21%,while that of sludge biochar is 44.29%,which is about twice as much as sludge;heavy metal ions are in line with the risk screening value of heavy metal content in soil agricultural land;the optimal parameters of microbial immobilization by composting sludge biochar are as follows: the dosage of biochar is3 g.The temperature was 15 ℃,the rotational speed was 150 rpm,and the adsorption time was 6 h.(3)Ten groups of pot experiments were designed to determine the degradation rate of petroleum hydrocarbons,changes in soil physical and chemical properties,changes in the number of microorganisms,enzyme activities and changes in soil community structure.After 90 days of pot experiment,the petroleum hydrocarbon degradation rate of sludge + sludge biochar immobilized microorganism group(CS + BCIB)was the highest,59.00%,which was 13.86% and 10.65% higher than that of sludge free bacteria group(CSB)and sludge biochar free bacteria group(BCB),respectively.The number of microorganisms and OTU in CS + BCIB group were the most,the enzyme activity was the highest,and the soil community structure was the most abundant.GC-MS analysis showed that the degradation effect of CH on C15 ～ C36 carbon chain was excellent,and CS + BCIB group had the best degradation effect,the mechanism of enhanced remediation of petroleum contaminated soil by immobilized microorganism of sludge and sludge biochar was found to be synergistic effect of biological stimulation and biological enhancement.