Start-up of an Integrated Process of Denitrifying Phosphorus Removal Coupled with Partial Nitritation and Anaerobic Ammonium Oxidation

Abstract

An integrated process uses an anaerobic baffled reactor combined with a fully mixed reactor (ABR-CSTR) as a test carrier for low-carbon, high-ammonia nitrogen (NH4+-N ≥ 200 mg·L-1) wastewater under continuous flow operating conditions; the normal anaerobic sludge in different compartments is subjected to domestication and cultivation to realize denitrifying phosphorus removal, partial nitritation, and anaerobic ammonium oxidation, thereby achieving the coupling effect of the three. Partial nitritation was successfully achieved in the A4 (CSTR) section by the strategy of limited oxygen (dissolved oxygen DO=0.8 mg·L-1) and intermittent aeration (exposure ratio=30 min:30 min) after 30 days. Subsequently, a strategy of shortening the hydraulic retention time (HRT) was adopted to achieve a stable operation of partial nitritation, and a stable influent substrate of NO2--N/NH4+-N 1.0-1.1 was provided for anaerobic ammonium oxidation. The anaerobic ammonium oxidation function was achieved after 154 days in the A5 and A6 compartments. The removal rates of NH4+-N and NO2--N were 94% and 97%, respectively, and the NO3--N concentration in the effluent was stable at 22 mg·L-1. The denitrifying phosphorus removal function was successfully achieved in the A1-A3 compartments by using NOx--N in the reflux as an electron acceptor. The removal rate of PO43--P was 77%. The integrated process was successfully coupled through 175 days, achieving simultaneous removal of C, N, and P.