Study on the effect of photosynthetic bacteria on the structure and function of microbial communities in activated sludge systems

The phototrophic bacteria were introduced into the Photoheterotrophic Sequencing Batch Reactor (PSBR) to treat simulated domestic wastewater. The effects of the amount of phototrophic bacteria, pH, light intensity, and dissolved oxygen (DO) on the pollutant removal performance of the reactor were investigated, and the impact of phototrophic bacteria on the microbial community structure, function, and nitrogen metabolism pathway of the active sludge microorganisms was revealed through 16S rRNA sequencing technology. The results showed that the addition of 10% phototrophic bacteria improved the removal rates of CODCr, NH4+-N, and TN in the PSBR system by promoting the coordinated functions between microorganisms. The optimum pH, light intensity, and DO for nitrogen removal performance in the PSBR were determined to be 7, 5000lux, and 3mg/L, respectively. The introduction of phototrophic bacteria enhanced the microbial diversity and abundance in the active sludge, with an increase in the relative abundance of Proteobacteria phylum and norank_f__Saprospiraceae genus. The abundance of functional genes (amo, hao, and nap) and enzymes (AMO, HAO, and NAP) involved in partial nitrification and denitrification processes was increased by phototrophic bacteria, thereby enhancing the overall nitrogen metabolism potential of the active sludge. © 2024 Chinese Society for Environmental Sciences. All rights reserved.