Novel S2EBPR

A novel sidestream enhanced biological phosphorus removal (S2EBPR) system was stably operated for 203 days under controlled conditions, including an influent C/P ratio of 25.8, a sidestream flow ratio of 20%, and an oxidation-reduction potential of -150 to -300 mV. This setup enabled effective synergy among Candidatus Accumulibacter, Dechloromonas, and fermentative microorganisms in the sidestream, without reliance on Tetrasphaera. During the two-stage operation, COD and PO4^3--P removal efficiencies improved from 73.7% and 75.3% to 83.2% and 91.8%, respectively. High biological activity was indicated by a peak phosphorus release of 49.3 mg/L, a 66% increase from Phase I. Microbial analysis showed enrichment of Candidatus Accumulibacter (12.9%) and Dechloromonas (6.2%) in the mainstream reactor, along with key phosphorus-removal genes and enzymes. These findings confirm the stable performance of the system and the effective cooperation between dominant PAOs and fermentative microbes. Future research should focus on optimizing operational parameters and evaluating scalability for cost-effective and stable nutrient removal in full-scale wastewater treatment.