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A novel aerobic electrochemical membrane bioreactor with CNTs hollow fiber membrane by electrochemical oxidation to improve water quality and mitigate membrane fouling

Yang, Yue, Qiao, Sen, Jin, Ruofei, Zhou, Jiti, Quan, Xie
Water research 2019 v.151 pp. 54-63
activated sludge, anodes, carbon nanotubes, cleaning, electrochemistry, filtration, fouling, membrane bioreactors, microbial communities, oxidation, water quality
A novel electro-assisted membrane bioreactor (EMBR) was constructed by integrating conductive carbon nanotubes hollow fiber membranes (CNTs-HFMs) into an aerobic activated sludge system. Herein, the CNTs-HFMs served as anode and filtration core simultaneously. Contrasted with the other two MBRs (PVDF-HFMs and CNTs-HFMs without electro-assistance), the effluent COD and NH4+N were lower than 40 mg/L and 3 mg/L at +1.0 V even HRT as short as 4 h. However, they were mostly over 50 mg/L (COD) and 5 mg/L (NH4+N) under the same conditions in the other two MBRs. The hydraulic cleaning for electro-assisted CNTs-HFMs was carried out only once during 60-day operation, and the permeate flux recovered to 100% of the original status. While four and five times hydraulic cleaning were executed for other two MBRs (PVDF-HFMs and CNTs-HFMs), respectively. Furthermore, merely 50 min continuous electrochemical oxidation was enough to resume flux of the heavily fouled CNTs-HFMs, i.e. flux recovered to 2020.87 L/(bar•m2•h) from 394.68 L/(bar•m2•h) (pure water flux, ∼2200 L/(bar·m2·h)). Simpson and Shannon indexes indicated enhanced microbial community stability in EMBR. Thus, electro-assisted CNTs-HFMs endow EMBR excellent anti-fouling ability and good effluent quality.