Effect of Volumetric Exchange Ratio on Nitrogen Removal in UniFed SBR Process

In order to investigate the effect of volumetric exchange ratio on nitrogen removal in novel UniFed SBR process,two UniFed SBR reactors were operated at the volumetric exchange ratio of 25%and 42% respectively to treat real domestic wastewater.The effect of volumetric exchange ratio on nitrogen removal was analyzed by comparing the degradation rules of TN during a whole cycle and TN concentrations of effluent at 6 group identical feedρ(C)/ρ(N)ratios at 25%and 42%respectively.The results showed that when UniFed SBR process was operated at any volumetric exchange ratio,a corresponding maximum TN removal efficiencyη_1max during feed/decant period always existed.η_1max was only relative to volumetric exchange ratio and irrespective of feedρ(C)/ρ(N)ratio.When the carbon sources of influent were sufficient,the bigger the volumetric exchange ratio,the lowerη_1max was.When at the same feedρ(C)/ρ(N)ratio,the bigger the volumetric exchange ratio,the higher TN removal efficiency was.TN removal during feed/decant period contributed more to UniFed SBR process,so the use of smaller volumetric exchange ratio was beneficial to TN removal of the whole process.