Study On Operation Regulation, Monitoring Optimization And Restoration For Stable Treatment Of Municipal Wastewater With A~2/O Process

Based on the functions of nitrogen and phosphorus removal, the A²/O process is playing an important role in water pollution control. But the function of nitrogen and phosphorus removal can't be further improved, because of restricting by its multiple self-factor. So, improving the function and extending application of A²/O process has become the new subject in wastewater treatment field. Furthermore, the wastewater of combined sewage system has special characteristics of low C/N and high content of N and P.These problems have greatly hindered the efficant and stable operation of sewage treatment equipment. Therefore, it is very important to timely and accurately evaluate the operation status of system, diagnosis the abnormal conditions, puts forward solving countermeasure, and improve process function by enhancing ANAMMOX technology. The study has great significance in the water pollution controll domain, especially in Waterbody Eutrophi cation control field.This thesis is based on the project of process technology upgrade and transform in wastewater treatment plant supported by Shanghai Committee for Urban Construction and Transportaion. By simulating real system of Bailonggan wastewater treatment plant, the research investigated the effect of temperature and F/M on system, and study treatment efficiency after enhancing ANAMMOX technology. The purpose of experiment was to explore the impact effect of low C/N, put forward solving technique, attempt to establish the monitoring and evaluating system of biochemistry indexes and further improve the nitrogen and phosphorus removal function.The results showed that the temperature and the processing functions of A²/O process were closely related. And the seasonal change had some negative effect on treatment efficiency. COD removal rate was rising from 70% to 85% when temperature changed from 15℃to 25℃, and removal rate was stable when the temperature was up to 25℃. The temperature range of 25℃-30℃was the best for denitrification, and too high or too low temperature could inhibit function of nitrogen removal. In this temperature range, the removal rate of TN was about 70%; nitrification could reach to 95%. The influence of temperature variation on the phosphorus removal was limited, but the phosphorus removal could easily be affected by operation condition. So, the fluctuation of phosphorus removal was large, and average removal rate was 50%.The best range of F/M for COD remove was 0.14-0.22gBOD₅/gMLSS·d. The best range of F/M for denitrification was 0.125-0.23gBOD₅/gMLSS·d. The best range of F/M for nitrification was 0.14-0.28gBOD-5/gMLSS·d, and best range of F/M for phosphorus remove was 0.14-0.23gBOD₅/gMLSS·d. In summar, the best range of F/M for the A²/O system was 0.14-0.22gBOD₅/gMLSS·d. It was slightly higher than the design standard of A²/O. It was show that increasing F/M was an effective solution to the problems encountered in low C/N wastewater treatment system.Biochemical index of DHA,PHB,OUR and ATP could not only reflect the organic matter degradation efficency of microbe, but also could judge the organic matter degradation velocity and operation conditions of the treatment equipments The suitable range of DHA was 30-40mgTF/gTSS·h, upper limit value was 60mgTF/gTSS·h, too high or too low concentration of DHA could lower effluent quality. Temperature and routine F/M had distinct influence on the synthesis of PHB, the concentration of PHB in anaerobic tank is between 23mg/gMLSS-28mg/gMLSS, mean consumption 140mg PHB could uptake 1mg phosphorus. Normal OUR was between 7.1-13.3mgQ₂/gMLSS·h, conventional value of nitration OUR was between 0.88-2.95mgO₂/gMLSS·h, the value of OUR was correspondingly adjusted by temperature. Increase the F/M was benefit to the OUR, but high F/M would inhibit nitrification and negatively affect the function of nitrogen removal. ATP could characterize the quantity of living microbe of activated sludge, the range of ATP was between 1.14-1.86mg/gMLSS, the influence of temperature and F/M on ATP was related to growth and reproduction of microbe, the upper limit value of ATP was about 2.08mg/gMLSS. PCR-DGGE could effectively analyze the community structure variation of AOB and NOB which was the man parts of Nitrobacteria The variation of temperature could easily make the successions of Nitrobacteria The species of community was relatively abundant when the temperature was low, but the community structure was stable when the temperature was high. The dominant bacteria of AOB were AOB₂, AOB₄ and AOB₆. The chief NOB of microflora was Nitrobacter of which dominant bacteria was Nb₇, Nb₈, Nbg. And the NP₂ was the mainly of Nitrospira. Just like the effect of temperature, the man microbes of AOB were AOB₂, AOB₄ and AOB₆ when the F/M changed. But the main species of Nitrobacter were Nb₁, Nb₂, Nb₄ and Nb₇, and the Np₆ of Nitrospira, which was different with the temperature On the other hand, the results showed that F/M <0.15 BODs/gM LSS·2d was beneficial to the growth of nitrification floraEnhancing the nitrogen and phosphorus removal function of A²/O process by ANAMMOX technology was an effective way. The results showed that lowering DO in aeration tank cloud result in effective accumulation of NO₂^--N, enhance ANAMMOX function, and strengthen nitrogen removal in the system. More 15% NH₄⁺-N and more 9% TN could be removed respectively in the anoxic tank. More 7% TN could be removed in the whole system. But lowering DO had negative influence on the function of COD and TP removal, and the removal rate of COD and TP decreased 5% and 1.4% respectively.TN removal by ANAMMOX is account for 21.9% of TN removal rate in system, the reaction medium was NH₄⁺-N and NO₂^--N, and generated small amount of NO₃^--N in reaction process. The proportion of those factors was 1:1.256:0.155; the best range of pH for ANAMMOX reaction was 7.8-8.0. DO could restrict ANAMMOX, and temperature had great influence to the reaction rate The reaction rate decreased from 1.47mg/L·h to 1.175mg/L·h when temperature changed form 30.6℃to 24.6℃.The results of shocking and restoring experiment showed that the nitration function could be greatly limited by wastewater of which C/N was 3.5. The denitrification function could completely stop when C/N was 1.2, meanwhile it could result in the fast decrease of COD and TP removal, and in sludge bulking and floating sludge. Increasing reflux ratio could effectively shorten restoration time, and the removal rate of NH₄⁺-N, TN and COD could be improved 20%,7.4% and 5.4% respectively. But this method had no effect on phosphorus removal. Increasing F/M and lowering SRT could also improve the processing function of system, the removal rate of NH₄⁺-N, TN, COD and TP could be improved about 5%, 4.7%, 7.4% and 4.5% respectively. The method could also improve the bioactivities of sludge, and the nitrification OUR and nitrosification OUR could be improved about 7% and 5.7% respectively.