Study on the Fouling Propensity of Effluent from the MBR System for the Electronics Wastewater with High Salinity

To the electronics wastewater with high salinity,the fouling propensity of effluent from the membrane bioreactor（ MBR） system played an important role for the design and long-term operational sustainability of the MBR ＋ Reverse Osmosis（ RO） system. In this text,the effluent quality,settling performance and membrane fouling were researched with three dimension excitation-emission fluorescence spectra（ EEM） and scanning electron microscope（ SEM）-Energy Dispersive Spectrometer（ EDS）. The results showed that there were few organics with a strong adhesion in the effluent. The metal ions in the effluent not only had a complexation reaction with the macromolecules fulvic acid and protein but also with silicon colloid. It caused a compact fouling layer on the RO membrane surface. But the organics and most of inorganic matters could form settling of flocs and be removed from the effluent by improving p H of the effluent,which would relieve the membrane fouling. In addition,the removal of metal ions in the fouling layer was critical for enhancing the cleaning efficiency of RO membrane.

Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment

Membrane separation technology has made great progress in various practical applications,but the unsatisfactory separation performance of prevailing membrane materials hampers its further sustainable growth.This study proposed a novel nonpolar super-aligned carbon nanotube(SACNT)membrane,which was prepared with a layer-by-layer cross-stacking method.Through controlling the number of stacked SACNT layers,three kinds of SACNT membranes(SACNT_200,SACNT 300,and SACNT_400)were prepared.Systematic characterizations and filtration tests were performed to investigate their physico-chemical properties,surface wetting behavior,and filtration performance.Compared with two commercial membranes(Com_0.22 and Com_0.45),all the SACNT membranes achieved smoother and more uniform structures.Due to the hexagonal graphene structure of CNTs,the surface chemistry of the SACNT membranes is simple and inert,thereby potentially eliminating the covalent-bonding-induced membrane fouling.Besides,the SACNT membranes exhibited a typical nonpolar wetting behavior,with high contact angles for polar liquids(water:~124.9°-126.5°;formamide:~80.0°-83.99)but low contact angles for nonpolar diodomethane(~18.8°-20.99).This unique nonpolar feature potentially leads to weak interactions with polar substances.Furthermore,compared with the commercial membranes,the SACNT membranes obtained a significantly higher selectivity while achieving a comparable or higher permeability(depending on the number of stacked layers).Moreover,the SACNT membranes exhibited superior separation performance in various application scenarios,including municipal wastewater treatment(2.3 times higher cleaning efficiency),electro-assistant fouling inhibition(or even self-cleaning),and oil/water separation(>99.2%of separation efficiency),suggesting promising application prospects in various fields.