Experimental Research On Nitrogen And Phosphorus Removal With Biofilm-SBR Hybrid Process

Shortage of water resource is an important restricting-factor of the economy and society development in China,and a great deal of municipal sewage drains directly into water body without any treatment or with little treatment which is a main reason that the quality of water environment has been deteriorating as a whole.In recent years,the water body eutrophication phenomenon such as "ShuiHua" and "ChiChao"of inland river,lakes and inshore water area occurs frequently,which brings serious harm to the source of drinking water,fishery and city landscape etc.Study to show,nitrogen and phosphorus pollution is the leading factor that arouses water body eutrophication. So it is urgent to research and develop simple,high-efficient and low-consumptive treatment techniques for removal of nitrogen and phosphorus of municipal sewage correspond to the situation of China.Infused the campus sanitary sewage and suspended carrier into SBR(Sequencing Batch Reactor)reactor,nitrogen and phosphorus removal efficiency have been researched.The Biofilm-Sequencing Batch Reactor(SBR)Hybrid process is consisted of anoxic time,anaerobic time,oxic time.The suspended carrier is added into the pond to attain a better treatment effect of biological nitrogen and biological phosphorus removal by combining biofilm and activated sludge process.In this experiment,the rate of carrier fill is 30%.The aeration pipes are laid symmetrically on the margin of the pond bottom.The carrier flows anti-circularly and symmetrically by air current driving.In the pond,oxic respiration and anaerobic respiration is replaced with each other periodically along with time and space.The removal rate of COD,NH₄⁺-N and TP can reach over 95.2%,95%and 75%.From the experimental DO and pH curve-point analysis,validated and showed the degradation of organic carbon,nitrogen and phosphorus removal are complete in this process.The experiment improved the traditional operating mode of SBR process on the base of the conclusion of SBR process characteristics and operational control,and the best operating pattern is found by the experimental results on SBR for campus sanitary sewage treatment.At the same time the paper also investigates the factors that affect SBR to treat campus sanitary sewage such as sludge retention time(SRT),sludge load, dissolved oxygen(DO),pH and so on.On the side,the paper studies the effect of suspended carrier addition to the SBR in order to strengthen the removal speed and removal rate of N and P.The results of the experiments show that the suspended carrier can enhance the potential capacity of SBR on to COD,N and P.After two months of this system operates normally,carried out twice temperature tolerance tests and destructive tests.Experiments show that the Hybrid process has stronger ability to repel temperature change and impact load and the excellent ability to prompt start.The test results of campus sanitary sewage treatment shows that the Hybrid process has a high treatment efficiency to COD,NH₄⁺-N and TN removal and can remove TP at the same time.The effluent concentration of COD,NH₄⁺-N,TN and TP can reach the Grade I of National Discharge Standards(GB 18918—2002)when the operating parameters are arranged reasonably.It is obvious that the process has the advantage of less land area,low construction investment,low energy consumption and convenient management.Therefore,the Hybrid process can be widely used in small towns after it has been improved further.