Effect of Substrate Ratio on Removal of Nitrogen and Carbon Using Anaerobic Ammonium Oxidation and Denitrification

Abstract

Real domestic sewage was treated in a sequencing batch reactor (SBR). When the partial nitrification of SBR was achieved, the effluent was fed with quantitative NaNO2, which served as the influent of the anaerobic ammonium oxidation (ANAMMOX) process of the anaerobic SBR (ASBR). The effect of different substrate ratios on the removal of nitrogen and carbon using anaerobic ammonium oxidation and denitrification was investigated under conditions with a temperature of 24℃ and pH of 7.2±0.2. The results showed that ① the nitrogen removal efficiency was optimum when the influent NO2--N/NH4+-N was 1.4-1.6. The average effluent concentrations of NH4+-N, NO2--N, and chemical oxygen demand (COD) were 2.14, 1.07, and 30.50 mg·L-1, and their removal rates were 93.62%, 97.79%, and 74.75%, respectively. The △NO2--N/△NH4+-N and △NO3--N/△NH4+-N ratios were 1.60 and 0.17, respectively. Total nitrogen was removed by the joint action of denitrifying and ANAMMOX bacteria. ② When the influent ratio of NO2--N/NH4+-N increased, the contribution of ANAMMOX to nitrogen removal decreased, but the contribution of heterotrophic denitrification to nitrogen removal increased gradually. ③ The NH4+-N and NO2--N degradation processes corresponded with zero-order reactions and fitted the linear relationship in the typical cycle. Their specific degradation rates were 0.404 and 0.599 mg·(g·h)-1, respectively. Their ratio was 1.48, and the specific degradation rate of COD gradually increased.