Advanced nitrogen and phosphorus removal in pilot-scale anaerobic/aerobic/anoxic system for municipal wastewater in Northern China.

Removing nitrogen and phosphorus from low ratio of chemical oxygen demand to total nitrogen and temperature municipal wastewater stays a challenge. In this study, a pilot-scale anaerobic/aerobic/anoxic sequencing batch reactor (A/O/A-SBR) system first treated 15 m3/d actual municipal wastewater at 8.1-26.4 °C for 224 days. At the temperature of 15.7 °C, total nitrogen in influent and effluent were 45.5 and 10.9 mg/L, and phosphorus in influent and effluent were 3.9 and 0.1 mg/L. 16 s RNA sequencing results showed the relative abundance of Competibacter and Tetrasphaera raised to 1.25 % and 1.52 %. The strategy of excessive, no and normal sludge discharge enriched and balanced the functional bacteria, achieving an endogenous denitrification ratio more than 43.3 %. Sludge reduction and short aerobic time were beneficial to energy saving contrast with a Beijing municipal wastewater treatment. This study has significant implications for the practical application of the AOA-SBR process.

Novel three-sludge municipal wastewater treatment process coupling denitrifying phosphorus removal with anaerobic ammonium oxidation.

The two-sludge anoxic dephosphation (DEPHANOX) process frequently encounters the challenge of elevated effluent ammonia levels in practical applications. In this study, the anaerobic ammonium oxidation (anammox) biofilm was introduced into the DEPHANOX system, transforming it into a three-sludge system, enabling synchronous nitrogen and phosphorus elimination, particularly targeting ammonia. Despite a chemical oxygen demand/total nitrogen ratio of 4.3 ± 0.8 in the actual municipal wastewater and 4.5 h of aeration, the effluent total nitrogen was 13.7 mg/L, lower than the parallel wastewater treatment plant. Additionally, the effluent ammonia reduced to 5.1 ± 2.5 mg/L. Notably, denitrifying phosphorus removal and anammox were coupled in the anoxic zone, yielding 74.5 % nitrogen and 87.8 % phosphorus removal. 16S rRNA gene sequencing identified denitrifying phosphorus-accumulating organisms primarily in floc sludge (Saprospiraceae 7.07 %, Anaerolineaceae 1.95 %, Tetrasphaera 1.57 %), while anammox bacteria inhabited the biofilm (Candidatus Brocadia 4.00 %). This study presents a novel process for efficiently treating municipal wastewater.