Research On The Characteristics And Influence Factors Of Biological Nitrogen And Phosphorus Removal In MSBR

It is very significant to remove nitrogen and phosphorus from wastewater. By changing operation condition, the characteristics and influence factors of biological nitrogen and phosphorus removal were analyzed. The experimental results showed as follow:When SBR operated in aerobic condition , the removal efficiency of organics was stable and averaged removal efficiency is as high as 83.3%, the averaged removal efficiency of NH4+-N is as high as 85.6%, and the averaged removal efficiency of phosphorus is 64.3% with the decrease of temperature and the increase of sludge loading.Phosphorus can be removed completely when SBR operated in anaerobic/oxic condition. The maximum rate of releasing phosphorus is 30 mgP/gMLSS h, and the averaged rate of releasing phosphorus is 3.38 mgP/gMLSS h; the maximum rate of accumulation of phosphorus was 14 mgP/gMLSS h, and the averaged rate was 7.64 mgP/gMLSS h. In this system, it takes 30-45 min to release phosphorus completely, while the accumulation of phosphorus need 30min.The averaged and maximum rates of the releasing and accumulation of phosphorus can be improved, when MSBR operated in alternative anaerobic/oxic and step-feed in anaerobic phase. The result showed that about 20%-30% of influent is enough to remove phosphorus, and the release of phosphorus decline with the decreasing of the amount offirst influent.Denitrifying dephosphatation can be foud when MSBR operated in anaerobic /anoxic/ oxic condition. Denitrifying dephosphatation process was completed in 35min when 6.6 mg/L NO3--N was added into the reactor and secondary influenting in anoxic phase. Theoretically, the amount of the denitrifying dephosphatation can get the maximum value9.31 mg/L, when 6.6 mg/L NO3- -N was added into the reactor . when the ratio of influent was 20%, the amount of the denitrifying dephosphatation was 5.2 mg/L, and the maximum rate of the denitrifying dephosphatation was 3 mgP/gMLSS h.According to the experimental results, optimisting the operating parameter, improving the removal efficiency of denitrifying and dephosphous, saving energy can be achieved through changing the ratio of influent and operating mode of denitrifying dephosphatation in the municipal wastewater treatment process.