Asbr Reactor Anaerobic Ammonia Oxidation Of Quick Start And Denitrification Performance Research

With the influent water distribution based on the municipal sewage, the fast start-up and denitrification performance of ANAMMOX reaction in ASBR was studied in this paper. The experiment conditions were as follows:the temperature was35±1℃, HRT was24hours, influent pH was7.2～7.5, influent NH4+-N and NO2--N concentrations were both40～160mg/L, TN volumetric load was0.08～0.34kgTN/m3·d. Inoculating the mixture of aerobic short-cut nitrification sludge and ANAMMOX sludge with the proportion of2:1, the ANAMMOX reaction was successfully started-up in49days and realized a stable operation. The experimental results show that:at the stable state the average NH4+-N、NO2--N removal rates were96%and98%respectively; the ratio of NH4+-N、NO2--N removal and NO3--N formation was1:1.05:0.29; After been started-up, the reactor’s effluent pH value was higher than influent; the average TN removal rate was79.7%; the synergistic effect of denitrifying and ANAMMOX realized part of COD removal; the dominant flora bacteria was mostly spherical with a funnel-shaped gap, it had the typical characteristic of ammonia-oxidizing bacteria.When the reactor was at stable stage, through the variation analysis of NH4+-N, NO2--N, NO3--N, COD concentration and pH value in one operation period, we can draw a conclusion that:without deoxidizing processing of the influent, the aerobic nitration, anaerobic ammonium oxidation(ANAMMOX) and anaerobic denitrification were simultaneously existed in the ASBR reactor; at the first2hours of one operation period the aerobic nitration was mainly happened, and at this process little ammonia nitrogen or nitrite nitrogen was oxidized into nitrate nitrogen, making the effluent nitrate nitrogen concentration raised significantly and removing the oxygen poison for other anaerobic reactions; later, ANAMMOX and little denitrification were happened, making the NH4+-N and NO2--N removed at the same proportion and the NO3--N concentration maintained stable; finally, the synergistic effect of denitrifying and ANAMMOX was happened, at this monument the NO3--N was non-complete denitrified into NO2--N which was needed in ANAMMOX reaction.After the ASBR has realized stable, its influence factors was studied. Such as the influent matrix nitrogen (N4+-N and NO2--N) concentration, the hydraulic retention time (HRT), the operation temperature (T). Through the analysis of the system denitrification performance and operation stability, the conclusions were:(1) The influent matrix nitrogen concentration research:at this experiment stage, the influent NH4+-N and NO2--N concentrations were both raised from70mg/L to160mg/L, while other influent conditions and operation conditions were not changed. When the influent matrix nitrogen concentration was raised to100mg/L, the removal rates of NH4+-N and NO2--N still remained close to100%, the TN removal rate reached85%; when the influent NH4+-N and NO2--N concentrations were raised to130mg/L simultaneously, the removal rates of NH4+-N and NO2--N fell to80%and90%respectively, TN removal rate fell to80%, the ANAMMOX reactivity began to be restrained; when the influent NH4+-N and NO2--N concentrations were raised to160mg/L simultaneously, the removal rates of NH4+-N and NO2--N fell to60%and71%respectively soon, TN removal rate fell to60%, the reactors’denitrification performance was influenced significantly, ANAMMOX and denitrifying activity were both restrained; when the influent NH4+-N and NO2--N concentrations were reduced to80mg/L simultaneously, the removal rates of NH4+-N and NO2--N recovered to87%and91%respectively soon, TN removal rate recovered to75%, system ran stably in the next20days. When the system C/N was at1～1.6, TN removal rate reached80%, it had a nice denitrification performance; during the cultivation of ANAMMOX sludge, the relationship between TN removal rate and operation days was:R=0.50·t+3.26.(2) The HRT research:at this experimental stage, the influent NH4+-N and NO2--N concentrations were controlled at about70mg/L, T for35℃, influent pH for7.2. When the operation HRT was24h, the removal rates of NH4+-N and NO2--N were both close to100%, TN removal rate reached up to85%, system had a very nice denitrification performance; when HRT was shortened to18h, the removal rates of NH4+-N and N02--N were still close to100%, TN removal rate was80%, but the NO3--N production increased, this phenomenon indicated that the denitrifying role at system nitrogen removal weakened due to the shortage of reaction time; when HRT was continued shortening to12h, system denitrification performance was significantly affected, the removal rates of NH4+-N and NO2--N fell to58.5%and66.7%respectively, TN removal rate fell to52.9%, due to the shortage of reaction time, both the role of ANAMMOX and denitrifying at nitrogen removal weakened.(3) The temperature research:at this experimental stage, the influent NH4+-N and NO2--N concentrations were still controlled at about70mg/L, HRT for24h, influent pH for7.2. When the operation temperature was35℃, the removal rates of NH4+-N and NO2--N were both close to100%, NO3--N production was about20mg/L, TN removal rate was83%, system had a good denitrificaiton performance and operation stability; when the temperature was lowered to25℃, system denitrification performance was slightly affected, the removal rates of NH4+-N and NO2--N fell by10%and15%respectively, NO3--N production fell by3mg/L, TN removal rate fell by8%, the contribution of ANAMMOX at system nitrogen removal fell by14.3%, however, denitrifying bacteria still had a good reaction activity; when the temperature was lowered to15℃, system denitrification performance was seriously affected, the removal rates of NH4+-N and NO2--N fell to57.1%and67%respectively, the average TN removal rate was62.6%, NO3--N production was negative, low temperature had an serious influence on ANAMMOX activity. The relationship of ANAMMOX velocity and temperature was R= [0.62-(T—17.04)]2·{1-exp[0.05·(T—43.28)]}2, while the experiment data was fitting with Ratkowsky model. From this fitting line, we could also draw that the ANAMMOX velocity reached its maximum value(12mgN/g Vss·d) at31℃.