[Pre-precipitation of Sewage-SNAD Granular Sludge Process Test]

Using artificial water, the simultaneous partial nitrification, ANAMMOX (anaerobic ammonium oxidation), and denitrification (SNAD) granular sludge process was started in a sequencing batch reactor (SBR), and then the ammonia concentration in the influent was reduced gradually. After stable operation for a period of time under the low ammonia concentration, sewage treated by a pre-precipitation process was used as a substrate to investigate the performance and stability of the SNAD granular sludge process. The results show that after the SNAD process was successfully started, the ammonia removal rate was greater than 98%, and total the nitrogen removal rate was about 89%. As the influent ammonia concentration decreased, the nitride-oxidizing bacteria (NOB) activity was increased and the total nitrogen removal rate gradually decreased to 75%. When the pre-precipitated domestic sewage (NH₄⁺-N 52-63 mg·L^-1, COD 99-123 mg·L^-1) was used as the inflow, the average effluent removal rate of the total effluent was 73.2%, the effluent COD concentration was below 35 mg·L^-1, and the maximum effluent ammonia nitrogen and total nitrogen concentration were 0.7 mg·L^-1 and 12.8 mg·L^-1. The ammonia and total nitrogen concentration in the continuous 30 day effluent reached the 1A level of the integrated discharge standard of water pollutants for municipal wastewater treatment, indicating that the removal of organics and nitrogen from domestic sewage was achieved efficiently and synchronously.