Manganese cycle-mediated synchronous bacteria-algae/anammox coupled denitrification system under low-temperature conditions
The study constructed a manganese redox cycle-mediated synchronous bacteria-algae/anaerobic ammonium oxidation coupled denitrification system (SAAD) and investigated the feasibility of enhancing the low-temperature resistance of the anammox-coupled denitrification process by adding Mn@BC.The results demonstrated that under low-temperature conditions, the average nitrogen removal efficiency increased to 82% with Mn@BC addition, whereas it remained at 73% with BC alone. Additionally, Mn@BC supplementation enhanced extracellular polymeric substance (EPS) secretion and enriched the microbial community structure.Furthermore, the rapidly growing microalgae absorbed substantial amounts of nitrogen and phosphorus through photosynthesis, achieving synchronous N&amp;P removal, with the phosphorus removal efficiency maintained at 51%. TOC analysis confirmed that photosynthesis generated dissolved organic carbon (DOC), thereby reducing the system's reliance on external organic carbon sources.Metagenomic sequencing was employed to investigate the functional microorganisms and potential metabolic pathways. By integrating reactor performance, sludge characteristics, and microbial community structure, the microbial interactions were elucidated, thereby proposing a potential mechanism of the Mn@BC-enhanced SAAD system under low-temperature conditions.