The Biological Toxicity Evaluation Of High-Salinity Oil Extraction Wastewater To Organism On Different Indicators

Oil extraction wastewater quality composition is complex,containing a wide variety or high concentrations of toxic and harmful pollutants,difficult to biodegradable and rarely reflected in the existing physical and chemical monitoring indicators.At present,the sewage discharge standards lack the biological indicators that characterize the toxicity of waste water,leading to the destruction of natural water bodies,the potential ecological risks,and the potential for further harm to human health through the food chain.This study is intended to take the oil extraction wastewater from the Beihai oil treatment terminal as the experimental object.The Vibrio-qinghaiensis sp.Q67,Scenedesmus obliquus,Selenastrum capricornutum and Daphnia magna these different trophic levels as test subjects.Using different methods to test period produced wastewater treatment processes(raw water,ABR pool,ABR effluent,SBR pool,effluent)acute toxicity,chronic toxicity and enzyme activity effect,the toxicity removal efficiency of the wastewater treatment wastewater in the processing section of Weizhou terminal sewage treatment plant and the toxic effect of the wastewater on the different indicator organisms were explored.The main conclusions are as follows:1)The specific concentration of zinc nitrate solution was prepared as the toxic reference of the test,and the potential biotoxicity of the oil extraction wastewater was tested by the susceptibility of Vibrio-qinghaiensis sp.Q67 to different seasons.The results showed that there were significant differences in the biotoxicity of the wastewater from different treatment processes in different seasons.In April,the toxicities of the tested wastewater were:YS~a>ABR~a>ABRc~a>SBR~a>CS~a,in August,the effluent toxicity size:ABR~b>ABRc~b>YS~b>SBR~b>CS~b.Combined with the pollution level of waste water and biological toxicity classification,in April the treatment process of the stage of the oil extraction wastewater toxicity grade followed by raw water for the high toxicity,ABR water for poisoning,ABR water for low toxicity,SBR water for low toxicity,effluent water for low toxicity;the toxicities of the oil extraction wastewater in the treatment section of the month are high toxicity,ABR water is highly toxic,ABR effluent is highly toxic,SBR water is low toxicity,and the effluent shows low toxicity.The results show that the oil extraction wastewater of the terminal sewage treatment plant has a certain effect on the removal of its toxicities after a series of biochemical treatment,but still has a certain degree of threat to the natural water environment.2)The results founded that the two kinds of green algae were used to study the effects of the two kinds of green algae,such as Scenedesmus obliquus and Selenastrum capricornutum.The results showed that the sensitivity of Selenastrum capricornutum to the oil extraction wastewater was stronger than that of Scenedesmus obliquus.Based on the influence of oil extraction wastewater on the five toxicity indexes of green algae,it was found that the sensitivity of the five toxicity indexes to the wastewater was:T-SOD activity>CAT activity>chlorophyll a>inhibition rate>chlorophyll b.3)The use of Daphnia magna to test the treatment process of the oil extraction wastewater,the water biochemical treatment of oil extraction wastewater after a certain degree of physical and chemical indicators to reduce,but the toxicity did not decrease the trend.The toxicity of the oil extraction wastewater to Daphnia magna was YS~a>CS~a>SBR~a>ABRc~a>ABR~a in April,and in August,the oil extraction wastewater was the same as that of Daphnia magna in different seasons.The toxicity of Daphnia magna was ABRc~b>YS~b>ABR~b>CS~b>SBR~b.To sum up,we can see that the three different trophic level of the tested organisms have different sensitivities to the toxicities of the oil recovery wastewater.Based on the experimental study of this paper,it can provide theoretical guidance for scientific evaluation of the possible risks of oil extraction wastewater in each process section and provide scientific basis for the revision of industrial wastewater safety standard and water environment standard.