Study On Screening And Identification Of Oil Degradated Strains And Treatment Of Oil Wastewater

Food wastewater caused growing pollution, while the microbial treatment technology had no secondary pollution, dealing with low cost has received widespread attention by people. But the microbial degradation process usually be influenced by factors such as source of microorganisms, environmental conditions,which limited its to be popularized use. So screening natural microbial strains, optimizating the process technology to improve degradation rate were key to applying microbial treatment technology.This article was selected 4 strains from the sludge and sewage of Canteen outfall,which had the ability of oil degradation.Through oil degradation experiment found that strains CY-5 and CY-47 had better oil degradation.And the strain CY-5 had good emulsifying ability. By integration of the physiological and biochemical identification and 16S rDNA, the result showed that strain CY-5 initially identified as Bacillus amyloliquefaciens,while stain CY-47 was Bacillus licheniformis.The growth curve of strains CY-5 and CY-47 were measured.The results show that they entered the logarithmic phase after 4h,respectively at 20h and 22h entered the stabilization period and then decline period.By single factor experiments,the best fermentation conditions of strain CY-47 was confirmed.The results showed the best conditions of strain CY-47 for oil degradation were:inoculum 10%,initial pH 9.2,temperature 37℃,rotation speed 250 rpm, salinity 1%.Under optimal conditions,when the oil concentration of 2 g/L,after 96h cultivation the degradation of oil reached 97.97%,and it was 24 h shorter than before,and the oil removal rate increased by 13.3%.As the strain CY-5 has the characteristics of emulsification,so the emulsification performance of the strain CY-5 was researched.The result showed that the emulsification index EI24of strain CY-5 was 65%.To shorten the processing time,the surfactant producing strain CY-5 was compounded with strain CY-47 to oil removal experiment.By single factor optimization of compounded strains CY-47 and CY-5,the results showed that when the strain CY-5 and CY-47 were at complex ratio of 1:2,inoculum 8%,initial pH9.2,temperature 35℃,200rpm of the rotation speed,0.5% of salt concentration,the oil degradation rate in 72 h was up to 98.81%.Compared with single bacteria degreasing,at the same rate of oil degradation,the processing time reduced at least 24 h.On the basis of the preliminary,the actual wastewater treatment was studied.The results showed that 6h after inoculation the compound strains entered logarithmic phase,while at 24 h emulsion oil is over the most.When at 66 h the biomass reached the maximum 13.46.At 72 h the oil degradation rate is 98.69%,and CODcr removal rate of 92.64%.Activity of lipase,amylase and protease were maximum in 54 h,respectively 3.46 U/ml,93.41 U/ml and 44.06 U/ml.From those research,oil waste water treatment of compound strains works well,and this research would provided some guidance for the large-scale practical application.