| With the rapid development of economy,the demand of oil is gradually increasing all over the world.The water pollution caused by the oil development process has become an urgent environmental problem.In this paper,the wastewater treatment process of oil production in Liaohe Oilfield was designed by using the method of biological as the main method amd chemistry as the support one.The hydraulic retention time and the main degradation characteristics of 2,4-dimethylphenol and n-hexadecane degradation bacteria are studied as well.In this paper,according to the characteristics of high temperature and high salt water content in Liaohe Oilfield,the treatment process of primary biological contact oxidation? ozone pre-oxidation ? secondary aeration bio-filter ? ozone ultraviolet oxidation was designed and the experiment was also carried out in laboratory level.The results showed that when the influent COD and oil content were 309.4 mg/L and 23.1 mg/L,the optimal hydraulic retention time of the primary biological contact oxidation,ozone pre-oxidation stage,secondary aeration bio-filter and ozone is 8 h?0.5 h?6 h and 0.75 h respectively.The removal rate of COD was 34.9%,47.3%,64.3%and 87.9%,respectively,and the oil removal rate was 40.7%,57.6%,74.0%,and 88.3%respectively.The COD and oil content of effluent were reduced to 37.5 mg/L and 2.7 mg/L respectively,which met the "Standard for Pollutant Discharge of Oil and Natural Gas Exploitation" and standards of corresponding enterprises.The analysis of the organic components of the oil wastewater by GCMS showed that the organic matter in the wastewater was dominated by 2,4-dimethyl phenol and n-hexadecane.A mixture of two organic compounds was used as the sole carbon source to elect LH-1,and n-hexadecane was used as the sole carbon source to screen LH-2 and 2,4-dimethylphenol as the sole carbon source to elect LH-3.Using 16sRNA LH-1 and LH-3 were identified as Pseudomonas sp.,while LH-2 was Bacillus sp.The degradation characteristics of LH-1,LH-2 and LH-3 were studied experimentally.The effects of temperature,salinity and substrate concentration on the degradation of the bacterial strain were determined by single factor experiment.The results showed that after culturing 96h the degradation rates of LH-1 to 2,4-dimethylphenol and n-hexadecane were 32.4%and 42.0%,respectively.The degradation rate of LH-2 to n-hexadecane was 47.9%The degradation rate of 2,4-dimethylphenol was 23.6%.The optimum culture conditions of LH-1 strain were temperature = 40 ?,salinity = 10 g/L and substrate concentration = 400 mg/L;the optimum culture conditions of LH-2 strain were temperature = 45 ?,salinity = 5 g/L,substrate concentration = 600 mg/L and the optimum culture conditions for LH-3 strain were temperature = 45 ?,salinity = 5 g/L and substrate concentration = 200 mg/L.Overall these three strains have a strong tolerance of high temperature and high salt environment.The results in the degradation process of organic matter by using LH-1,LH-2 and LH-3 strains showed that LH-1 and LH-3 strains produced Catechol 2,3 dioxygenase,so LH-1 and LH-3 uses the meta-open-loop process to degrade aromatic hydrocarbons organic matter;while LH-2 do not have both enzymes,so it cannot degrade aromatic substances.This paper designs and successfully runs the wastewater treatment process,and discusses the microbial mechanism of biochemical treatment of oil wastewater,which can provide technical support and theoretical basis for the oil wastewater. |
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