Research On Optimizing Operation Of The Process Combined With Bio-ecological Technology For Rural Sewage Treatment

With the pollution of rural sewage becoming more and more serious,a lot of research on rural sewage treatment technology has been done in China and abroad.But most of them are for decentralized rural sewage,and research on relatively concentrated rural sewage treatment technology and Management model are not many.From the research direction and practice results,bio-ecological combination technology is better than biotechnology and ecological technology.In this paper,the bio-ecological combination process of oxidation ditch-ecological pond is taken as the research object,and optimizing operation of the process combined with Bio-ecological technology for rural sewage treatment is carried out.The main conclusions are as follows:The results show that the best operation scheme of the oxidation ditch is:ZLB37 aerator for 24 hours,ZLB22 aerator 8:00～20:00 continuous open,DQT2.2-1400 low-speed submersible water impeller 20:00-8:OOcontinuous open.Through the continuous monitoring of the influent and outflow of the oxidation ditch from July to October 2017,the removal rate of CODCr is less affected by temperature,the removal rate of ammonia nitrogen and TN is influenced by temperature,and the removal rate of TP is not affected by temperature.When the wastewater entering the oxidation ditch,the concentration of CODcr,ammonia,TN and TP decreased first,and then decreased slightly.While the change of nitrate and nitrite concentration is opposite,The concentration of nitrate and nitrite in the effluent of the oxidation ditch is higher than the influent,but the concentration of nitrite is always lower than 0.15mg/L,and the concentration of nitrate nitrogen is not more than 2.41 mg/L.The removal rate of ammonia nitrogen and TN in ecological ponds is greatly affected by temperature,and the difference of summer and winter removal rates reached 11.50%and 17.56%,respectively.The removal rate of CODcr and TP was relatively small.The first section of the ecological pond can effectively remove most of the organic matter in the sewage and has a strong function of removal nitrogen and phosphorus.The second and third sections continue to remove the organic matter and remove most of the nitrogen and phosphorus.The removal rate of pollutants increased with the increase of the coverage rate of ecological floating islands.When the coverage rate increased to 30%,the removal rate of nitrogen and phosphorus increased about 7%,and the increase rate of CODCr removal rate was slower than that of nitrogen and phosphorus,which indicates that the ecological floating island has a good effect on removing nitrogen and phosphorus in the sewage.The effect of the combination of oxidation ditch and ecological pond on the removal of pollutants is studied.The results show that except winter the effluent of the system can stably meet the first grade A standards of Urban Sewage Disposal Plant Contamination Integrated Discharge standard.The removal efficiency of CODcr is more than 85%except December and January in winter.The removal rate of ammonia nitrogen and TN in combination process decreased with the decrease of temperature,and the TN removal rate in November,December and January was less than 70%.The removal efficiency of TP was relatively stable,and the removal rate was more than 90%.The operation and maintenance costs of the sewage treatment facilities include power costs,staff salaries and ecological pond maintenance costs,calculated the direct operating costs of 0.424 yuan/ton.In summary,the oxidation ditch-ecological pond combination process is a technology with highly efficient and low consumption,suitable for relatively centralized rural sewage treatment technology.