High reuse potential of effluent from an innovative vertical submerged membrane bioreactor treating municipal wastewater

The main objective of this study is to investigate the reuse possibility of effluent from a vertical submerged membrane bioreactor (VSMBR) treating municipal wastewater. The average removal efficiencies of total chemical oxygen demand (COD), total nitrogen (T-N), and total phosphorus (T-P) were 96, 74, and 78%, respectively at 8-h hydraulic retention time (HRT) and 60-day sludge retention time (SRT). Additional removal of organic matter and improved nitrification and denitrification efficiencies were found by the formation of a dynamic membrane. The effluent quality of the vertical submerged membrane bioreactor (VSMBR) could satisfy most items in the current drinking water standards of Korea and the WHO (World Health Organization). Accordingly, the reuse of the effluent from the VSMBR could be possible for various purposes such as toilet flushing, sprinkling, and car washing.

The average effluent quality from the pilotscale MBR of 8-h HRT is summarized in Table 5. It can be seen that all the listed items except for microorganisms and NH3-N met the current drinking water standards of Korea and the WHO. In these regards, the VSMBR effluent could be suitable for potable use after disinfection. However, a concern whether drinking water standards were adequate to ensure the safety of all waters is still under dispute as there is a limit to complete filtration by MF membrane of pathogens that can cause health problems. Despite of technological advances and high quality of treated effluents, public reactions to direct potable reuse are unfavorable. Comparatively, reuse of the effluent for municipal purposes including toilet flushing, sprinkling, car washing, and cleaning were more prone to public acceptance considering its quality [9]. In addition, the MBR effluent could be used for irrigation purposes. After simple treatment, the effluent may also be applied to In this study, the pilot-scale VSMBR was operated at various HRTs in order to remove organic matters and nutrients from municipal wastewater. As a result, it was found that average removal efficiencies of T-N and T-P were 74 and 78%, respectively at 8-h HRT. Accordingly, additional removal efficiency of organic matter by the formation of a dynamic membrane was found to be about 4% under various HRTs. Nitrification and denitrification efficiencies also improved about 5 and 4%, respectively by aerobic and anaerobic biofilms. The effluent quality of the VSMBR of 8-h HRT could satisfy most items in the current drinking water standards of Korea and drinking water guidelines issued by the WHO. Finally, the VSMBR was regarded as an effective and compact process as it showed high removal efficiencies of not only SS and organics but also nutrients. Especially, this process can be strongly recommended for the advanced wastewater treatment and water reuse purposes in urban and rural area.