The Development Research Of Bioremediation Complex Bacteria For Oily Sludge

Oily sludge containing a large number of toxic and hazardous substances has extremely complex composition and has been classified as hazardous solid waste.Based on the seriousness of oil pollution hazards,the harmless treatment of oily sludge is imminent.In this paper,we separated and screened high-efficiency petroleum hydrocarbon degrading bacteria from oil-containing sludge,and based on the analysis of the degradation effect of single strain GC-MS,a rational and scientific construction of complex flora was performed.The single-factor test was used to explore the optimal degradation conditions of petroleum hydrocarbon degrading bacteria.The mixed-microbial agents were immobilized by adsorption method and applied to the repair of oil-bearing soils.The optimal conditions for immobilization were investigated.Immobilized microspheres were prepared by embedding method,and its application was extended to achieve better results in the removal of oily wastewater.The conclusion is as follows:(1)Five strains with petroleum hydrocarbon degradability were screened and purified in oil sludge samples from the Long-dong oil sludge treatment station and named as LD3,LD5,LD7,W6,and XB.Through morphological observation and physiological and biochemical identification,it was initially determined that XB belonged to Planococcus migula sp.,W6 belonged to Micrococcus cohn sp.,LD3 belonged to Streptococcus sp.,and LD5 and LD7 belonged to Staphylococcus sp.The results of shake flask degrading experiments show that the degradation rate of LD3 is the highest up to 78.28%;the next best is LD7 and W6 reaching 71.28% and 60.46%;XB and LD5 had lower degradation rates of 59.58% and 59.80%,respectively.(2)The optimal degradation conditions of 5 strains petroleum hydrocarbon degrading bacteria were investigated through a single-factor test.The initial pH of the culture solution in the 5 strains was optimally 7;the optimal inoculum size of LD3,LD7,and XB are 6%,LD5 and W6 are 4% and 1%,respectively;The best degradation temperature for 5 strains is 30℃;The petroleum hydrocarbon concentration for 5strains with the highest degradation rate is 8 g/L;The degradation time for 5 strains when the bacteria achieved the best degradation efficiency is 7 days.Because mixedculture results show an antagonism between LD3 and LD5,combined with the degradation advantages of various strains,LD3,LD7 and W6 was selected to construct complex bacteria agent.By use of GC-MS,residual components of crude oil degraded at the tests were analyzed,which results show that the complex bacteria agent can degrade most of alkanes in crude oil with length between C13-C35,and greatly improves the degradation ability.(3)The results of orthogonal experiments at different inoculum size of 3 strains show that when the inoculation ratio of LD3,LD7 and W6 was 6%,2% and 6%,inspectively,the best degradation effect was observed.The optimal conditions for the preparation process of the immobilized microbial inoculant were as follows: the optimal immobilization time was 36 h for straw and peat as a carrior and 30 h for charcoal;the straw immobilized microbial agent.The optimal carrier dosage to immobilize microbial agent areis 3.0g,3.0g and 2.0g for straw,peat and optimal,inspectively;The optimal pH for the degradation of the immobilized microbial agent are 7.0,7.5 and 7.5 for straw,peat and charcoal,inspectively,as a carrior;The optimal immobilization temperature for all three kinds of was 35℃.(4)Indoor simulation repairs of oily soil in situ were performed for 40 d.For remediation of unsterilized oily soil with immobilized bacteria agents,the degradation rates of the petroleum hydrocarbons were as follows: peat immobilized bacteria agent74.12% > charcoal immobilized bacteria agent 70.25% > straw immobilized bacteria agent 60.74% > free mixed bacteria 35.48% > control treatment(non-added bacteria)11.98%.During the process of remediation of sterilized oily soil,the degradation rates of petroleum hydrocarbons were as follows: charcoal-immobilized microbial agent70.75%> peat-immobilized microbial biomass agent 69.90%> straw immobilized microbial agent 68.28%> free-mixed bacteria 44.30%> control treatment(non-added bacteria)2.21%.(5)Using straw and charcoal carrier as adsorbent,sodium alginate as embedding agent and calcium chloride as cross-linking agent,sodium alginate-straw/charcoal embedded microspheres were prepared and embedded in the carrier and immobilized.The degradation rate of petroleum hydrocarbons by composite inoculants has been greatly improved compared to the embedded blank carrier.Among them,the hydrocarbon degradation rate of charcoal-immobilized inoculants is the highest,reaching 92.45%,and the straw immobilized microbial agent has also achieved87.65%;the degradation rate of the blanks immobilized by the two kinds of carriers is low,and the degradation rates of the blanks with charcoal and straw immobilization are 40.57% and 32.64%,respectively.