Study on carbon distribution of A/A-MBR combined process and its strengthening mechanism for nitrogen and phosphorus removal

TL;DR: In this paper, the positions of the anaerobic and anoxic sections were exchanged, and membranes were installed in the aerobic section of the traditional Anaerobic/anoxic/aerobic (A/A/O) process to create the "Anoxic/anaerobic-MBR" combined process, which was designed and run in a wastewater treatment plant in Wuxi City, China.

Abstract: In this study, the positions of the anaerobic and anoxic sections were exchanged, and membranes were installed in the aerobic section of the traditional anaerobic/anoxic/aerobic (A/A/O) process to create the “anoxic/anaerobic-MBR” combined process (A/A-MBR process). A pilot-scale A/A-MBR system with a treatment capacity of 2.0 m 3 /h was designed and run in a wastewater treatment plant in Wuxi City, China. The effluent of the vortex grid chamber of the plant was pumped to the pilot reactor. The results showed that the A/A-MBR combined process enhanced the biodegradation effect of the system. The influent carbon allocation measure can strengthen the pollutant removal efficiencies, thus improving the effluent stability and process reliability. The carbon distribution had little effect on the COD removal rates, which were stable at 90.42–90.97%. The influent distribution optimized the carbon source in the anoxic and anaerobic units and increased the overall nitrogen removal rates of the combined process. Because the low concentrations of soluble phosphorus and carbon limited the phosphate-accumulating organisms (PAOs) growth in the anaerobic unit, a reasonable distribution of an influent carbon source promoted the denitrification ability of the anaerobic unit. After carbon was distributed in the anaerobic unit, the average TN of effluent decreased from 13.93 to 10.87 mg/L, and the average TN removal rate increased to 67.97%. Most of the phosphorus in the influent was insoluble, and the efficient retaining ability of the membrane in MBR ensured a high TP removal effect. The TP of the effluent and the removal rates were 0.10–0.41 mg/L and 89.97%–98.30%, respectively.