Enhanced Removal Of Residual Organic Matter In The Tail Water Of Sewage Treatment Plant By The Biological Contact Oxidation

With the improvement of sewage treatment rate,the effluent from sewage treatment plants also increases correspondingly,and a large number of non-biodegradable or even non-biodegradable organic compounds in effluent bring new security risks to cities and natural water bodies.Based on the comprehensive analysis and evaluation of the water quality pollution and treatment characteristics,the combined treatment technology of seepage wall,anaerobic biofilter,segregated biological contact oxidation tank and constructed wetland are proposed by our research group.This paper mainly discusses the treatment efficiency and influence factor of the segregated biological contact oxidation tank for the organic matter and ammonia nitrogen under different working condition by field test study,and optimize design parameters of segregated biological contact oxidation tank according the test result.The main research results are as follows:Based on the analysis of dissolved organic matter in the water of the Xin river in‘fengxixincheng’of xi’an city,the results show that a large number of organic matter is not biodegradable or hard to biodegrade and those mainly are the soluble microbial metabolites from effluent of upstream sewage treatment plant,indicating that the water from the Xin river and effluent of the sewage treatment plant show strong similarity.Therefore,the water from Xin river is used as raw water in this experimentBased on the different operation characteristics of segregated and full-flow biological contact oxidation methods,COD and ammonia nitrogen were taken as the main investigation objects,and field tests were carried out on the two biological contact oxidation tanks under 8 different working conditions,and their operation effects were compared and studied.Manual inoculation hanging film method was used to start hanging film.However,the removal rate of the segregated system did not decrease slightly until the system was operating under the fourth working condition.After long-term operation,due to the continuous impact of airflow,the growth effect of biofilm in full-flow device is poor than the segregated device.The operation effect of biological contact oxidation method is better than that of full-flow method.In conclusion,the operation effect of segregated biological contact tank is better than the full-flow biological contact tank.On the basis of the analysis of raw water pollution characteristics and treatment characteristics,COD and ammonia nitrogen were determined as the main removal objects.Meanwhile,the removal effect of the process on total nitrogen and total phosphorus was investigated.The field pilot test was conducted under 8 different working conditions by using the segregated biological contact tank.The manual inoculation hanging film method was used to start the hanging film.On the 13th day,the COD removal rate of the system reached 32.53%and became stable.According the‘surface water environment quality standard’GB3838-2002,COD basically met theⅤclass standard and ammonia nitrogen and total phosphorus can meetⅣclass.Based on the above research results,the design parameters of the segregated biological contact tank in the bioremediation project of the black and smelly water body in‘fengxixincheng’section of the Xin river with a water treatment capacity of 15,000m~3/d are optimized,which can provide reference for the feasibility study and engineering design of the treatment of black and smelly water body in China and the removal of residual organic matter in sewage treatment plant effluent.