Main content area

A submerged membrane bioreactor coupled under unprecedentedly short hydraulic retention time enabled by non-woven fabric pre-filtration and electrochemical membrane cleaning

Chung, Chong Min, Yamamoto, Kazuo, Cho, Kangwoo
Journal of membrane science 2019
anodes, artificial membranes, cages, chlorination, chlorine, cleaning, electrochemistry, energy use and consumption, fabrics, fouling, hydraulic resistance, membrane bioreactors, microbial communities, microfiltration, nitrification, oxidation, restriction fragment length polymorphism, total nitrogen
This study reports that electrochemical oxidation (EO) coupled with non-woven fabric (NWF) filter synergistically mitigated fouling in a submerged membrane bioreactor (MBR) under hydraulic retention time (HRT) of 1 h. Our NWF-EO-MBR was equipped with NWF prefilter cage surrounding microfiltration (MF) membrane with IrO2 anodes in vicinity. Continuous operation showed a retarded increase of transmembrane pressure at intermittent current density (5 mA cm−2) to prolong operation duration by 40% under constant flux (13.75 L m−2 h−1). Primary separation of bio-flocs by NWF not only reduced physically removable fouling on MF, but also allowed augmented concentration of electrolytic free chlorine (FC) near 4.0 mgCl2 L−1 inside the NWF cage. The FC degraded dissolved foulants to reduce physically irremovable hydraulic resistance of MF. A limited nitrification under the short HRT was assisted by electrochemical breakpoint chlorination, resulting 72% total nitrogen removal efficiency on average. Terminal restriction fragment length polymorphism fingerprinting indicated that the microbial community in mixed liquor was less influenced by FC than that in bio-cake on MF. The energy consumption of EO was approximated to 28 Wh per m3 of permeate.