Determination of the Optimum NH$_3$-N/NO$_2$-N Ratio by Anaerobic Batch Test in Anaerobic Ammonium Oxidation Process

Nitrite and free ammonia have been known as substrate inhibitors in anaerobic ammonium oxidation. To reduce inhibitory effect of these substrates, the NH3-N/NO2-N ratio in the influent could be properly controlled in anaerobic ammonium oxidation process. Five kinds of NH3-N/NO2-N ratio were assayed in batch to find optimum NH3-N/NO2-N ratio, curtailing substrate inhibition. As the results of batch test, the highest T-N removal efficiency of 88% was obtained at 1.00 : 1.30 of NH3-N/NO2-N ratio. In addition, rate constants for ammonium and nitrite in zero-order kinetics were found to be the highest values as 7.66 mg/L.hr and 11.89 mg/L.hr at 1.00 : 1.30 ratio, respectively. However, as for the specific anammox activity, the ratio of NH3-N/NO2-N ratio was recommended as 1 : 1.15 which can maintain the highest SAA during continuous operation and preclude the accumulation of nitrite in the reactor.