The feasibility of a synergistic
endogenous partial denitrification-phosphorus
removal coupled anammox (SEPD-PR/A) system was investigated in a modified
anaerobic baffled reactor (mABR) for synchronous carbon, nitrogen,
and phosphorus removal. The mABR comprising four identical compartments
(i.e., C1–C4) was inoculated with precultured denitrifying
glycogen-accumulating organisms (DGAOs), denitrifying polyphosphate-accumulating
organisms, and anammox bacteria. After 136 days of operation, the
chemical oxygen demand (COD), total nitrogen, and phosphorus removal
efficiencies reached 88.6 ± 1.0, 97.2 ± 1.5, and 89.1 ±
4.2%, respectively. Network-based analysis revealed that the biofilmed
community demonstrated stable nutrient removal performance under oligotrophic
conditions in C4. The metagenome-assembled genomes (MAGs) such as
MAG106, MAG127, MAG52, and MAG37 annotated as denitrifying phosphorus-accumulating
organisms (DPAOs) and MAG146 as a DGAO were dominated in C1 and C2
and contributed to 89.2% of COD consumption. MAG54 and MAG16 annotated
as Candidatus_Brocadia (total relative abundance
of 16.5% in C3 and 4.3% in C4) were responsible for 74.4% of the total
nitrogen removal through the anammox-mediated pathway. Functional
gene analysis based on metagenomic sequencing confirmed that different
compartments of the mABR were capable of performing distinct functions
with specific advantageous microbial groups, facilitating targeted
nutrient removal. Additionally, under oligotrophic conditions, the
activity of the anammox bacteria-related genes of hzs was higher compared to that of hdh. Thus, an innovative
method for the treatment of low-strength municipal and nitrate-containing
wastewaters without aeration was presented, mediated by an anammox
process with less land area and excellent quality effluent.