Analysis On The Process And Dynamics Of Nitrogen And Phosphorous Removal In Improved Type Carrousel Oxidation Ditch For Treating Municipal Sewage

This test sets a modified form of Carrousel oxidation ditch of a sewage treatment plant in Zhengzhou city as its study object. It mainly researches on the effect of the N and P removal. With the material balance analysis of each section and the study of each procedure of those sections, combined with simulation analysis of specific procedure kinetic model, the kinetic equations and parameter values of each section are preliminary modified. The main results are as follows:(1)The material balance is analyzed on the basis of the quality of the water in and out of each section of the modified Carrousel oxidation ditch. The removal of COD mainly happens in sectionⅡ, with a rate of 47.75%; the removal of TN happens in section I, with a rate of 75%; NH3-N is mainly removed in sectionⅡ, the removal rate is 74.25%; the removal rate of organic nitrogen differs little in the four sections; the release of phosphorus mainly happens in the preposed oxygen-deficient tank, the anaerobic tank, and sectionⅠof the oxidation ditch, and the absorbing of phosphorus happens mainly in the sectionⅡ, the ratio of absorption and release of P amounts to 1.20.(2)The material balance analysis of the modified Carrousel oxidation ditch is studied as a whole. By the calculation of the material balance of C, N and P, we get the balance percentages of the three in practical operation which are 95.7%,85.36% and 86.33% respectively. The removal of C is completed with the form of CO2, with a rate of around 70.5%; the removal of N is completed with the nitrification and denitrification, with a rate of about 60.3%; the removal of P is completed by the discharge of sludge of rich phosphorus, the rate is 83%.(3)The ammonization, short range denitrification, the full range denitrification and the release of P happen in the pre-oxygen deficient tank, the anaerobic tank and sectionⅠof the oxidation ditch. In some cases, there is also the phenomenon of denitrification and P-absorption in the anaerobic tank. There are mainly the ammonization, nitrification, and P-absorption in sectionⅡof the oxidation ditch. (4)Combining the kinetic model of each section with the material balance, determining the parameters set and dynamic parameters of the kinetic model.Comparing and contrasting the simulation value with the measured values, and determine the accuracy of the models.(5)Through the analysis of various test results, it is observed that there are two problems with the biotreatment:one is that the ammonia nitrogen is substandard; the other is that the f-value is low. Possible solutions are suggested.