Screening Of Oil-Degradation Strains And Preliminary Study On Biodegradation Of Oil Wastewater

Food wastewater has become one of the major sources of water pollution in China,and efficient removal of oil from catering wastewater has become an urgent environmental issue.Physical and chemical methods were commonly used to be separating wastewater and oil,however,which were easy to cause secondary pollution,high energy consumption and high investment.Biodegradation has received widespread attention because it was a clean,efficient and simple treatment,but the microbial degradation process was easily affected by the environmental conditions.Therefore,it was necessary to optimize the technology to improve microbial degradation rate.This article sampled the sewage from the canteens of Guizhou University and the vegetable market of Guiyang City,through the primary screening and rescreening to get target strains with high oil degradation.At the same time,to provide a theoretical basis to the optimization of subsequent microbial degradation of oil,the paper also explored the degradation trend of 435 immobilized lipases under different environmental conditions.The main conclusions were as follows:This work selected two strains,Xo and Mh,from sewage of NO.4 canteens,Eastern canteens and Laochaoyang area of Guizhou University and Taiciqiao vegetable market in Guiyang City,and the strains degradation rate in 24 hours of the two strains was 39.5%and 29.8%,respectively.The strains Xo and Mh were identified as Serratia marcescens and Fusarium oxysporum by molecular biological identification.Preliminary studies on strain characteristics of the two strains showed that strain Xo grow stably at temperatures between 20 ?-25 ? and pH between 4.0-9.0,which has high research valueIn the experiment of optimizing strain Xo to degrade oil,single factor experiment,Plackett-Burman experimental design and Box-Behnken response surface experiment were used to be sure that the optimal environmental conditions were incubation time 72 h,rotate speed 180r/min,inoculation volume 10%,NaCl 0.15%,oil 1.97%,initial pH 8.94 and temperature 35.5 ?.The degradation rate of bacterial Xo oil was 81.49%,which was 2.06 times higher than that before optimization Under this condition,the degradation rate of strain Xo was 81.49%,which was 2.06 times higher than before optimizationThe process parameters such as the catalytic reaction time of 435 immobilized lipases,the rotate speed,the catalytic reaction temperature,the initial pH of the environment and the amount of 435 immobilized lipases were optimized one by one The degradation rate of oil was determined to be 88.21%under the conditions of catalytic reaction time 12 h,rotate speed 160 r/min,reaction temperature 40?,addition amount 3%and initial pH 7.0-8.0For the 435 immobilized lipase using repeated time and consumption rate in the experiment,catalytic reaction time 12 h,rotate speed 160 r/min,reaction temperature 40 ?,immobilized lipase 3%and initial pH 7.0 were used to carry out repeated catalytic stability.In the study,after 72 h,6 times reactions,the oil degradation rate was only 32.17%,and the consumption rate reached 65.38%.