Surfactant Enhanced Bioremediation Of Petroleum Contaminated Soil

With the development of the modern oil industry, environmental problem has become increasingly serious.Bioremediation is recognized as adavantages of efficient, economic and no secondary pollution, it has become an promising remediation method.In this paper, we acclimated stably and efficiently mixed petroleum hydrocarbon degradation bacteria(MPHD) by using co-metabolism acclimation method. Determined and optimized the growth conditions of MPHD. Investigated the impact with addition of surfactant Tween80 and SDS on MPHD degradating petroleum hydrocarbon.Conducted a laboratory simulation experiment of MPHD remediation of petroleum contaminated soil in the present of Tween80.The main results were as follows:(1) Long-term benzenes contained activated sludge was used as bacteria source.The inducer was toluene, and the double-substrates acclimation methods was“Inducer-Intermediates-Substrates”.Catechol and petroleum hydrocarbons were choosed as carbon source.Identification results of high-throughput sequencing were:Rhodanobacter sp., Mycobacterium sp.,Rhizobiales sp., Bosea sp., Hyphomicrobiaceae sp., Streptomyces sp., Bacillus sp., Gemmatimonadetes sp., Rhodospirillaceae sp., Sphingomonas sp..Petroleum hydrocarbon degradation experiment results showed in the condition of 14% dosage and after 36 h culture time,the degradation rate was the highest, which was 42.31%、41.57%respectively.(2) Tween 80 and SDS solubilizated petroleum hydrocarbons experiment results showed:(1)The critical micelle concentration(CMC) of Tween80 in water was25mg/L. Tween80 showed astrong adsorption by soil particles when soil was added into water. To Tween80, no toxic was observed and could be a carbon source by the microorganism. The CMC of SDS in water was 1250mg/L.The adsorption with soil particles was not obviouse to SDS.Concentration greater than 600mg/L of SDS had a micro toxicity;(2)In water,the degradation rate of petroleum hydrocarbon reduced with the addition of Tween80 and SDS, however, in water-soil system, the degradation rate of petroleum hydrocarbon increased with the addition of Tween80 and SDS.In water-soil system, when Tween 80 concentration reached 5 CMC(125mg /L) the degradation rate of petroleum hydrocarbons was highest, which was 42.19%.When SDS concentration reached 2 CMC(2500mg/L) the degradation rate of petroleum hydrocarbons was highest,which was 30.95%.(3) Petroleum hydrocarbons degradation single factor experiment using flora shaker was conducted.The results showed:Optimum nitrogen source was(NH4) 2SO4,optimum phosphorus source was KH2PO4,optimum C:N:P was 100:4:0.67.The optimum environmental factors as:Temperature of 30-35℃ and initial pH of 7-8.(4) Laboratory simulation experiment of Tween80 enhanced MPHD remediation of petroleum contaminated soil was conducted. The results showd that during 80 days’ bioremediation, the petroleum hydrocarbons in soils was significantly reduced,soil properties changed greatly.The texture of soil changed from dark and blockto light and loose.The sample of S1 which added MPHD and Tween80 had a petroleum hydrocarbons degradation rate of 76.85% after 80 days, which is 1.6 times of samlpe S2 with MPHD only.