Partial Nitrification in Microaerobic Tank of "Anoxic-Anaerobic-Microaerobic-Aerobic (A2O2)" Biological Nitrogen Removal Process

The pilot-scale Anoxic-Anaerobic-Microaerobic-Aerobic (A(2)O(2)) biological nitrogen removal process was used to treat the wastewater from nitrogenous fertilizer production with C/N ratio of 1 similar to 2. Batch tests were conducted to investigate the patial nitrification using the activated sludge from the microaerobic tank rich in nitrite bacteria as the experimental object. Results showed that 95% removal efficiency of NH3-N could be obtained with the HRT of 30 h. The SW affected the NH3-N removal rate and the optimal SVI was 106 mL/g. The ORP was well correlated with the logarithm of NH3-N concentration with the linear regression equation of y=-57.233x+3.308. Moreover, the kinetic model for partial nitrification was determined as v = 4.7625/9.86+S