Improving simultaneous N, P, and C removal and microbial population dynamics in an anaerobic–aerobic–anoxic SBR (A-O-A-SBR) treating municipal wastewater by altering organic loading rate (OLR)
Shuli Liu, Heng Li, Jia Kang, Bingtao Liu, Gangfu Song, Yuhao Liu
Abstract
To assess the impacts of the influent organic loading rate (OLR) on the performance of an improved sequencing batch reactor (A-O-A-SBR system), four OLRs (1.35, 2.03, 2.70, and 3.38 g-COD/L/d) were used for enhancing simultaneous N, P, and C removals in the system. Results showed that high simultaneous N, P, and C removal efficiencies of the A-O-A-SBR were achieved with an OLR of 2.03 g-COD/L/d. The corresponding TN, TP, and COD removal efficiencies were 98.10%, 87.01%, and 93.43%, respectively. Dominant phyla, including Proteobacteria, Planctomycetes, Candidatus Saccharibacteria, Bacteroidetes, and critical genus Thiothrix, and essential classes such as Gammaproteobacteria, Betaproteobacteria, Sphingobacteriia, contributed to the excellent A-O-A-SBR performance. Functional genes forecasts demonstrated that the metabolic potential on pollutants degradation metabolism improved with the proper OLR condition.