In-situ reconstruction of birnessite functional film on gravity driven ceramic membrane bioreactor for manganese removal

Abstract

Purification of groundwater containing manganese contaminants has become an important task in protecting and conserving water resources. A vertical aeration-aided gravity driven ceramic membrane (GDCM) reactor was developed and applied to purify manganese continuously for 40 days in this study. The results indicated that the stable manganese concentration of effluent (<0.10 mg/L) was achieved due to the matured birnessite functional layer which gradually formed on ceramic membrane surface under vertical dispersion conditions. The “trade-off” effect within GDCMBR was solved via reconstructing the birnessite-type film and improving the water production flux (30–40 LMH). Coupling with vertical aeration reconstruction birnessite-type biofilm, GDCM concentrated MnOB efficiently, reaching >4 × 105 MPN/mL at the end and contributing to manganese removal, which could be also confirmed by the Electron Paramagnetic Resonance (EPR) analysis and Confocal laser scanning microscope (CLSM) analysis. Additionally, vertical aeration increased the MnOB species, including Bacillus, Leptothrix, zoogloea, Flavobacterium and Ferribacterium. Finally, the auto-catalytical oxidation mechanism of the dispersed birnessite was revealed via X-ray diffraction (XRD) analysis, XPS and Raman analysis. Vertical aeration assisted birnessite type functional layer GDCM is effective and promising, and with further optimization, this technology can potentially be considered as an alternative to safeguard the planet's drinking water supply.