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Electrically conductive membrane possesses a remarkable performance in antifouling with the assistance of applied external electric fields. However, its widespread application is hampered due to the poor properties of existing conductive membranes, such as low conductivity and inadequate strength. The present study demonstrates a novel in-situ combination approach for the fabrication of a highly conductive carbon nanotube (CNT)/polyvinylidene fluoride (PVDF) membrane. During membrane fabrication, the casting solution film was pre-mantled with a CNT layer before the occurrence of polymer precipitation, thereby ensuring a natural and tight in-situ mergence between the CNT layer and supporting PVDF. The obtained CNT/PVDF membrane was characterized in terms of physicochemical properties and filtration performance. An electrically-enhanced cross-flow filtration system was devised to evaluate the antifouling performance of the pristine PVDF and CNT/PVDF membranes. Compared with the pristine PVDF membrane, the CNT/PVDF membrane possesses a greater electrical conductivity and a higher permeability. The incorporation of the CNT layer led to a completely different surface composition in terms of elemental components and functional groups. Being used as a cathode, the CNT/PVDF membrane exhibited a remarkable antifouling performance in the presence of external electric fields, and performed better in a 0 V/2 V-pulsed mode as compared with a 2 V-constant mode. This in-situ combination method provides a simple and practical approach for the fabrication of composite conductive membranes, suggesting promising applications in various membrane-fabrication areas. [ABSTRACT FROM AUTHOR]

Polymeric flat-sheet membrane (FS) and ceramic flat-tubular membrane (CM) are the most widely-used membranes in anaerobic membrane bioreactor (AnMBR). However, fouling mechanism on FS and CM were rarely compared before and needed to be deeply illuminated. In this work, distinction of irremovable fouling formed on polyvinylidene fluoride FS and Al 2 O 3 CM in AnMBR treating municipal wastewater was studied. Lab-scale AnMBR operation showed that FS presented severer irremovable fouling and faster fouling rate. Foulants characterization revealed that irremovable fouling of FS was composed of more organics (FS = 0.91, CM = 0.35 g-TOC/m2-membrane) and biomass (FS = 47.3, CM = 8.65 × 1010 cell/m2-membrane), leading to gel layer loosely structured. Conversely, irremovable fouling of CM contained more inorganics (FS = 0.08, CM = 0.55 g/m2-membrane), facilitating dense gel layer with larger specific filtration resistance. Membrane cleaning tests found that gel layer on FS was efficiently removed by NaClO, while gel layer on CM was loosened by NaClO but destructed by citric acid. NaClO/NaOH both reduced resident bacteria, whereas increased the proportion of live cells. Irreversible fouling on FS involved more organics while more inorganics on CM. Irreversible biofouling could utilize citric acid as substrate for metabolism and proliferation. This study not only helps to probe fouling mechanism with different membrane materials, but also aids to develop differentiated effective cleaning strategy to corresponding membrane modules. Image 1 • Loosely structured gel layer on polymeric membrane contains more organics and biomass. • Dense and robust gel layer on ceramic membrane comprises more inorganics. • Gel layer on polymeric membrane is removed by NaClO degrading organics. • Gel layer on ceramic membrane is loosened by NaClO but destructed by citric acid. • NaClO reduces biomass on both membranes but increases the proportion of live cells. [ABSTRACT FROM AUTHOR]

In this study, a hollow fiber microfiltration membrane (HFM) coupled biocathode microbial desalination cell (MDC) was fabricated. With real wastewater flowing serially from anaerobic anode to oxic biocathode, filtered by the HFM and finally to the central membrane stack, the HFM-MDC took advantages of conventional anaerobic/oxic process, membrane biofilm reactor, and eletrodeionization technology, realizing advanced removal of organics, suspended solids, and salinity during 105 days of operation. The produced diluate was 86.1 v%, with final conductivity, chemical oxygen demand, total nitrogen, and total phosphorus (TP) reaching 59.2 ± 12.2 μS/cm, 35.5 ± 4.0 mg/L, 1.65 ± 0.39 mg/L, and 0.14 ± 0.05 mg/L respectively. The corresponding concentrate (13.9 v%) concentrated 6.7 times the initial conductivity (6044 ± 168 μS/cm), recovered 98.7% of phosphorous (TP of 40.9 ± 4.9 mg/L) and part of nitrogen. In addition, the HFM was stably operated for 105 days due to coefficient aeration flushing and regular chemical backwashing, with trans-membrane pressure keeping at ≤ 15 kPa for most of time. Moreover, this integrated process only needs wastewater as sole water input, and possesses a relative cheap HFM coupled biocathode compared with conventional Pt cathode, providing a promising solution for practical application of MDC in wastewater purification. [ABSTRACT FROM AUTHOR]

In the study, a novel electrochemically modified carbon nanofibrous anodic membrane (G/SnO 2 /CFs) is observed to be effective toward electrochemical oxidation of main emerging and refractory pharmaceutical. By innovatively incorporating graphene/tin dioxide (G/SnO 2) into carbon nanofibers (CFs), the electrooxidative performance and conductivity can be improved significantly by the significant electrooxidation capacity of SnO 2 and excellent electrical conductivity of graphene. Herein, the electrochemical filtration and degradation efficacy of the PAN-based G/SnO 2 /CFs microfiltration (MF) membrane filter was evaluated by the electrochemical degradation performance of refractory toxic organic - sulfamethoxazole (SMX). The study proved that, the increased anodic membrane amount and flow-through mode lead to enhanced degradation performance. 9 non-toxic smaller intermediates of SMX were identified by LC-MS/MS, so that the SMX transformation pathway was proposed. The excellent SMX degradation performance (85% removal efficiency) and membrane stability (10 cycles up to 50 h reaction) suggests the potential of G/SnO 2 /CFs MF membrane filter to treat the refractory toxic organic from wastewater. Image 1 • The SnO 2 and G/SnO 2 were synthesized successfully by in-situ hydrothermal approach • The electrospun PAN-based G/SnO 2 /CFs MF membrane flow-through filter was fabricated innovatively. • The outstanding electrochemical SMX degradation rate and membrane stability were obtained. • 9 non-toxic smaller intermediates of SMX were identified by LC-MS/MS • The SMX transformation pathways and intermediates toxicity evaluation was obtained [ABSTRACT FROM AUTHOR]