[Effects of Aerobic Carbon Sources on Biofilm with Simultaneous Phosphate Removal and Enrichment]

In a cyclic alternating O/A operation mode, phosphorus accumulating organisms (PAOs) can undertake phosphate removal and enrichment as the main process in wastewater treatment plants. The effects of the concentration of carbon sources during the aerobic stage on phosphate removal and enrichment performance of PAO biofilms, and the microbial population structure in the biofilms, were investigated. The results showed that the aerobic COD concentration decreased from 200 mg·L^-1 to 0 mg·L^-1, the phosphorus uptake rate improved by 1.29 times, the phosphorus concentration in effluent stabilized below 0.5 mg·L^-1, the phosphorus release rate increased by 3.56 times, and the phosphate concentration in the circulating solution increased from 27.125 mg·L^-1 to 55.91 mg·L^-1. With respect to the change in microbial communities, the identification showed that the abundance of Proteobacteria increased by approximately two times, and the enrichment effects of Rhodocyclaceae and Anaerolineaceae increased by 2.28 and 5 times, respectively. Reducing the concentration of the carbon source in the aerobic section was beneficial to the screening and enrichment of PAOs, strengthening the removal of phosphate in the aerobic section and the release of phosphate in the anaerobic section. This resulted in an enriched phosphate solution. These observations provide a theoretical basis for future urban sewage treatment plants seeking to reduce their carbon demand.