Conditions And Mechanisms Study In A/O/N Process For Nitrogen Removal Of Domestic Wastewater In Residential Communities

The research content in this dissertation was the nitrogen removal of A/O/N process for domestic wastewater treatment in residential communities.Conbined the design of the biological nitrogen removal reactor, the aim of the study was to improve the capabilitiy of nitrogen removal of the processes in existence and to provide theoretic gist and technical supports for the perfection of the water reuse process in residential communities.The A/O/N process in the experiment was brought out on the ground of conventional A/O process, which was an effective nitrogen removal process suiting for the wastewater with nitrogen of high concentration.Through dividing the aerobic area of conventional A/O process into two parts: carbon oxidation area and nitrification area respectively, it created optimum biochemical environment for specific growth of carbonaceous heterotrophs bacterias and nitrifiers,which could make them exert their removal effects fully.The idiographic content list as follows:(1) The study analysed the characteristic of the sewage in residential communities, and suggested that the septic tank should be forbidden in residential communities.Then through a parallel experiment between the A/O and A/O/N process under the condition of same energy consumption, the advantage of A/O/N process in nitrogen removal was confirmed.(2) Combined the characteristics of the sewage in residential communities and the characteristics of A/O process, an orthogonal test was designed and with the testing equipment designed by ourselves, the optimum conditions for A/O/N process to treat domestic sewage were determined as follows: HRT(A)=1.5h; HRT(O)=1.0h; HRT(N)=3.0h; MLSS=6000 mg/L; R(the mixed liquor ratio)=300%.(3) Through the contrastive experiment between the A/O and A/O/N process with the best process parameters, the advantage of A/O/N process was confirmed again, and by studying the mechanism of removing nitrogen, the simultaneous nitrification and de- nitrification in nitrification area was pointed out as an important factor in nitrogen removal. Through the impulsive load experiment it confirmed the capability of A/O/N process which put up with the impulsive loads. (4) The assumptions of A/O/N reactor were brought out and the fields worth of researching were pointed out.The results of the study demonstrated that compared with A/O process, the A/O/N process was more efficient in nitrogen removal under the condition of the same energy consumption, it was more suitable for wastewater with nitrogen of high concentration or water reuse in residential communities.