Effects of coagulant with different basicity on membrane-based biological treatment for removing phosphorus

With growing concerns about water resource or environmental issues such as eutrophication and algae blooms, regulation about water quality of effluent has been reinforced in wastewater treatment plants. Membrane bioreactor (MBR), integration of membrane and biological processes, is regarded as alternative method due to its high quality of effluent. Coagulants are often added into a bioreactor to comply with the rigid standard of phosphorus. Addition of a lot of coagulants have potential adverse effects on MBR performance such as membrane fouling and low removal efficiency. Therefore, this study attempted to investigate the impact on microorganism or membrane permeability when polyaluminium chloride (PAC) was added for phosphorus removal. In batch test, addition of PAC with lower basicity interfered with biological decomposition of organic matters. When the selected PAC with the highest basicity (71%) was employed in continuous MBR, the process showed stable TMP and high-quality treated water due to no negative effect on microorganism.