| In recent years,with the development of social economy,China’s water environment problems have become increasingly serious.In view of the current situation of China’s water environment,the tail water discharge requirements of sewage treatment plants will gradually increase.Taking the Orbal oxidation ditch of a sewage treatment plant in Chizhou as an example,the effect of oxidation ditch process on the removal of CODCr,BOD,ammonia nitrogen,total nitrogen,total phosphorus,heavy metal ions and persistent organic pollutants in domestic sewage was studied.Provide reference for the renovation of sewage treatment plants.(1)The research shows that the oxidation ditch process has a stable removal effect on COD and BOD in sewage,the average removal rate of COD reaches 68.34%,and the effluent compliance rate is 100%,indicating that Orbal oxidation ditch has strong adaptability to fluctuations of organic pollutants in wastewater..The oxidation ditch process has a poor removal effect on TP and TN in wastewater.The average removal rate of TN is 53.64%,while the TP removal rate is only 16.94%,which is not up to standard in 57.38%.(2)Oxidation ditch process The removal efficiency of heavy metal ions such as iron,manganese and zinc in sewage is more than 85%.The removal efficiency of heavy metal ions in the secondary sedimentation tank is much higher than that of the primary sedimentation tank.It is known that the oxidation ditch should be heavy metal.The main processing unit for ion removal.In addition,the study also shows that the removal efficiency of heavy metal ions in the oxidation ditch process increases with increasing temperature when the concentration of heavy metal ions has not reached the level of biotoxicity.(3)Analysis of the removal effect of volatile organic compounds showed that the main removal process of polycyclic aromatic hydrocarbons in 7 is the biological treatment stage of aerated sedimentation tank and oxidation ditch.The total amount of polycyclic aromatic hydrocarbons in the influent was 52.0 ng/L,and the total amount of polycyclic aromatic hydrocarbons in the effluent was 8.08 ng/L,and the removal rate was 83.1%.And the final removal rate of each polycyclic aromatic hydrocarbonis about 80%,which indicates that the Aubel oxidation ditch has a good removal effect on poly-alloys.(4)According to the engineering treatment requirements and the analysis of the existing treatment process,it is proposed to transform the existing Orbal oxidation ditch into the AAO process,add an intermediate lift pump room,add a medium efficient sedimentation tank,dosing room and a UV disinfection.The canal has enabled the sewage plant to reach the discharge standard of Class I A.(5)The post-reconstruction process flow shows that the removal effect of COD and BOD in sewage is stable,the total phosphorus removal effect reaches 94.2%,and the removal effect is obvious compared with about 16% before the transformation.And the average value of total phosphorus in effluent is only 0.15mg/L,the maximum value is 0.22mg/L,and the minimum value is 0.08mg/L.The total phosphorus effluent value fluctuates within a small range.The average concentration of TN influent was20.4 mg/L,the average effluent concentration was 5.28 mg/L,the removal efficiency was 59%,and the removal efficiency was significantly improved.Compared with about 53% before the transformation,ammonia nitrogen has a significant improvement,and the average ammonia nitrogen output is much lower than the emission standard of 5mg/L.The post-retrofit treatment process has no significant change in the removal efficiency of heavy metal ions such as iron,manganese and zinc in the sewage and the removal effect of polycyclic aromatic hydrocarbons.In this paper,through the monitoring and analysis of the treatment effect of domestic sewage treatment by oxidation ditch process before and after the reform,the operation effect and characteristics of Orbal oxidation ditch and the upgrading and reforming measures of Orbal oxidation ditch are discussed,which provides technical support for the upgrading of the same type of sewage treatment plant.,has a good reference value. |
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