Effective recovery of phosphorus from municipal wastewater could be one of the best practical alternatives to protect aquatic environments from eutrophication and save natural phosphorus resources. This paper focuses on validating magnesium carbonate (MgCO3)-based pellets combined with a bench-scale anoxic/aerobic membrane bioreactor (MBR) system for advanced phosphorus recovery from municipal wastewater. As the flow rate of wastewater into the MgCO3 column decreased from 10 L/d to 2.5 L/d, the phosphorus recovery rate of the MgCO3-based pellets increased from 54.3 to 93.5%. However, the column's severe clogging was found after a 13-days operation due to the high removal of total suspended solids (TSS) (~82%) through the MgCO3 column. The anoxic/aerobic MBR introduction provided efficient removal of TSS, organic matter, and ammonia nitrogen before the MgCO3 column. The combination of MBR with the MgCO3 column achieved 73.1% phosphorus recovery from municipal wastewater without physical clogging. The P recovery capacity of the MgCO3-based pellets was maintained at 0.47 mg ortho-P/g MgCO3-based pellet during the continuous operation. Physical and chemical properties of MgCO3-based pellets before and after the experiment were characterized using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface area analyzer.
Keywords: anoxic/aerobic membrane bioreactor system; magnesium carbonate pellets; municipal wastewater; phosphorus; recovery.