Start-Up Of A~2/O Process And The Change Of The Performance Of The System At Different Hrt And Different C/P

A2/O process has the function of meanwhile removing organic matter, nitrogen and phosphorus, was widely applied. But it has anaerobic, aerobic and oxygen three different environmental conditions, also it has different kinds of microbe groups, for exemple phosphorus enrichment fungus (PAO), denitrifying bacteria and denitrifying bacteria in the same sludge system. Thus, there exists the denitrifying bacteria and phosphorus enrichment bacterium competition for different sludge age and carbon source, meanwhile the backflow sludge carried in nitrate would inhibit phosphorus release in conditions of anaerobic. Due to these contradictions, it is impossible to realize the best growth conditions which three different function bacterium groups needed, This restricts mutually function result nitrogen phosphorus removal efficiency is not high. The study on the basis of the existing nitrogen and phosphorus removal theory, using artificial simulated biological wastewater, through controlling the main ecological factor to realize the optimization of reactor operation, and to explore nitrification and phosphorization removal influence at different HRT and different C/P in the system, in order to provides the theory basis for the engineering use of A2/O process.This experiment using artificial simulation sewage, Through the control glucose dosing quantity control COD value of fill water, dose NaHCO3control alkalinity, N and P controlled by NH4Cl and KH2PO4. In order to maintain the bacteria growth biochemical environment, dosing certain proportion of trace elements. The experiment sludge using surplus sludge from Wenchang sewage treatment plant Haebin.Through aeration cultivate45days by adding NH4Cl, glucose, KH2PO4, and trace elements to the sludge everyday. When vaccinate the sex sludge sedimentation was good, MLSS3358mg/L, VSS/SS0.53, the inoculation quantity accounted for about1/3every chamber volume.This experiment start in the form of anaerobic and anerobic directly plant sludge without domestication. Reactor temperature21±1℃, COD removal rate stability to90%after35days, A2/O reactor startup completed.After the reactor stability operated, change HRT, the test found HRT change had a little effect COD removal, and had the bigger influerce to NH3-N, TN and TP removal. NH3-N and TN removal rate would increase with the increase of HRT, TP removal rate would increase and decrease with the increase of HRT. Too high HRT would cause phosphorus removal rate was low. System function was better when HRT5-8h. Denitrifying carbon source was short beacase in organic content in the water was low, the main reason limit simultaneous nitrification denitrifying remove TN quantity is lacking of available COD in the process. Therefore, in the actual quote from process should increase glucose dosing quantity to ensure the carbon source enough. HRT not only is the important factors of influencing hydraulic loading, and also affect sludge concentration. Thus the influence of HRT on system is bigger on relative of other factors and has the advantages of easy to control. System should keep higher sludge concentration in order to achieve better decontamination ability. Consider energy consumption and removal, the best HRT of system was8h.The stable operation of the reactor premise, the test of changing C/P ratio find:In the condition of anaerobic/anoxia/oxygen volume ratio1:1:2, HRT8h, return sludge75%, reflux ratio200%to treat sewage. Each pollutant removal efficiency achieved best at C/P ratio45, TN and TP removal was77%and90%respectively, each pollutant removal efficiency reached the best state. In the same operation conditions treat sewage of C/P30%, COD and TN remove almost not affected, but PO43--P removal was reduced to65%, TP removal rate also significantly reduced, the experiment suggests that in the low C/P conditions, the system have denitrifying dephosphatation reaction, but the response was not significant. Each pollutant removal rate almost would not be affected in syetem at C/P60. But it is conducive to the growth of chitosan bacteria due to excessive concentrations of carbon sources, GAO become dominant population than PAO, causing decrease of phosphorus removal rate in the system. In addition, heterotrophic bacteria multiply, autotrophic denitrifying bacteria at a competitive disadvantage, system nitration performance also be affected.