The Research Of Screening And Degradating Optimization Of Oil Reduction Bacteria In Oil Wastewater

In recent years,with the rapid development of social economy,the petroleum and chemical products have been quite popular all over the world,and the demands are also increasing.With a large number of oil mining applications,the corresponding amount of petrochemical wastewater increase day by day,and compositions are more and more complex.The difficulties in processing the waste water are increasing,so how to treat the petrochemical wastwater has become an urgent important problem.And in the development process of oil wastwater treatment technology,people have been seeking the most economic and environmentally governance approach.And the micro processing technology is the best selection.So the study of oil reduction racteriain the wastewater has become an important subject.In this paper,the discussions were made from different aspects: the pollution hazard,the screening and identification of oil degrading bacteria,influencing factors of degradation conditions,the orthogonal experiments and the related research progress at home and abroad.The research provided basic theory to the practical application of oil wastewater treatment.Via a series of experiment study it showed that:(1)The oil wastewater was collected from ChangQing Petrochemical company in XianYang.After more than two months' domestication and purification,17 strains of oil degradation bacterias were isolated which named from GA-1 to GA-17 bacteria.Among them 13 strains were bacteria and the rest were the actinomycetes or fungi.When the oil concentrations were 2g/L,the oil degradation rates of GA-4,GA-6,GA-13 bacteria were greater than 30%.GA-4,GA-6 and GA-13 bacteria reached the best oil degradation rates,being 41.18%?34.82% and 30.72% respectively.And further experiments illustrated GA-4 bacteria belonged to Bacillus sp.,GA-6 bacteria belonged to Acinetobacter sp.,while GA-13 bacteria belonged to Rhodococcus sp..(2)Through the study of the influence factors of oil drop rate,it showed that the degradation time,initial oil content,temperature,pH,and bacteria inoculation amount all had great influence on oil degradation rate.The optimal temperature?pH?bacteria inoculation amount and the best oil concentration were as listed: GA-4 bacteria: 30 ??8? 5% and 2g/L;GA-6 bacteria: 28 ??7.5? 5% and 2g/L;GA-13 bacteria: 30??7.5? 6% and 2g/L.(3)3 strains(GA-4,GA-6,GA-13 bacteria),which had the better degradation rate were choosed from 13 strains of oil degradation bacteria and one high degradation rates bacteria,the experiments of mixed flora distribution were operated with P3 bacteria.When the mixed bacteria inoculation amount was 5%,and 4 strains of bacteria were added in the same proportion at the conditions of 30??180r/min,the degradation effects in different combination were researched in 7 days.The results showed that: on most condition the degradation rates of mixed bacteria were higher than single bacteria.The mixed bacteria worked togrther to improve the utilization rate of oil degradation.For example,when adding P3?GA-4 and GA-6 bacteria together,the oil degradation rate reached the best,being 60.73%.At the same time,there are some experiments showed that the degradation rates of mixed bacteria were lower than single bacteria,it illustrates antagonism is among different bacteria or different bacteria uses same degeradation substrate.For example,when adding P3?GA-6 and GA-13 bacteria together,the oil degradation rate was 52.21%.It was higher than the oil drop rate of GA-6 and GA-13 bacteria,but it was lower than the oil drop rate of P3 bacteria.(4)The orthogonal experiments of mixture bacteria(P3,GA-4,GA-6,GA-13 bacteria)were operated,and the order to change the dosing quantity of integrated oil drop were: P3>GA-4> GA-13> GA-6.The optimal dosing quantity of P3?GA-4?GA-6 and GA-13 bacteria were 2.0%?2.0%?2% and 1.5% respectively,at which condition the drop rates of oil reached 66.26%.Its oil drop rate increased by 9.73% than the best rate of P3 bacteria.