Application of nitritation from ammonium nitrogen-rich wastewater using sequencing batch reactor process

Recycle water containing high-load nitrogen returns to the main stream of a municipal wastewater treatment plant (MWTP) and causes increase of the nitrogen load in the main process. This study has evaluated economic, eco-friendly and energy-saving nitrogen process that uses nitritation in a sequencing batch reactor (SBR). The range of nitrogen removal efficiency was 70%–99%, and nitrite conversion efficiency was 0.5%–92.4% in a laboratory-scale SBR during overall operation days. The ammonium nitrogen removal efficiency was maintained at over 70% with various retention time conditions, but the nitrite conversion efficiency varied depending on the hydraulic retention time. Nitritation occurred at a short solids retention time (in case of this study it is 1 d) through the nitrite oxidizing bacteria washout in this SBR. The maximum ammonium nitrogen removal rate was 0.544 kg N_removed /(m³ d), and the nitrite conversion rate was 0.49 kg N_removed / (m³ d). Stable nitritation occurred at the influent ammonium nitrogen load ranging from 0.42 to 0.6 kg N/(m³ d), which was similar or even higher compared with other nitrogen treatment processes that use nitritation. For the application of nitritation to recycle water treatment (RWT) process in MWTP, nitrite build-up is an important factor to be considered in the selection of an appropriate treatment process. According to the results, an SBR is suggested as a method to increase the applicability of nitritation to RWT process in MWTP.