N, P and C removal simultaneously and microbial population numbers in a cyclic activated sludge system treating village and township domestic wastewater by altering the cycle times.

It was necessary to research an efficient treatment process suitable for township domestic wastewater. In this paper, the performance of the cyclic activated sludge system (CASS) system for simultaneous carbon (C), nitrogen (N) and phosphorus (P) removal was investigated by changing the operation cycle of the CASS reactor. Four operating conditions were set up, T1, T2, T3 and T4, with cycle times of 6, 8, 12 and 8 h (with carbon source), respectively. The results showed that the CASS system had good simultaneous removal of C, N and P. The highest removal rates of COD, TN, NH4+ -N and TP were 87.69, 72.99, 98.60 and 98.38%, respectively, at a cycle time of 8 h. The TN removal rate could be increased to 82.51% after the addition of carbon source. Microbial community analysis showed that Proteobacteria, Bacteroidetes and Candidatus Saccharibacteria were the main phylum-level bacteria. Their presence facilitated the effectiveness of the CASS process for nitrogen removal and phosphorus removal. Functional analysis of genes revealed that the abundance values of genes associated with C, N and P metabolism were higher when the treatment was effective.

Enhanced performance of simultaneous carbon, nitrogen and phosphorus removal from municipal wastewater in an anaerobic-aerobic-anoxic sequencing batch reactor (AOA-SBR) system by alternating the cycle times.

The performance of simultaneous carbon (C), nitrogen (N) and phosphorus (P) removal was investigated by altering the cycle times in an anaerobic-aerobic-anoxic sequencing batch reactor (AOA-SBR) system. Results showed that the AOA-SBR system achieved high simultaneous C, N and P removal efficiency with a cycle time of 6 h, with average removal efficiencies for COD, TN, and TP of 96.81%, 96.32% and 94.33%, respectively. The highest anoxic removal rate of NOX-N was 203.44 mg·g-1- MLVSS·d-1. Meanwhile, anaerobic release rate and aerobic, anoxic removal rate of TP reached peak values of 104.31 and 85.81 mg·g-1- MLVSS·d-1, respectively. Microbial community analysis demonstrated that Proteobacteria, Bacteroidetes and Candidatus Saccharibacteria at phylum level and Betaproteobacteria, Gammaproteobacteria, Sphingobacteriia, Deltaproteobacteria and Alphaproteobacteria at the class level benefited AOA-SBR performance. Functional analysis of genes indicated that the metabolic potential related to C, N and P metabolism increased under the optimal cycle time condition.