Biological wastewater treatment is not effective in removal of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). In this study, we fabricated a photocatalytic reactive membrane by functionalizing polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane with titanium oxide (TiO) nanoparticles for the removal of ARB and ARGs from a secondary wastewater effluent. The TiO-modified PVDF membrane provided complete retention of ARB and effective photocatalytic degradation of ARGs and integrons. Specifically, the total removal efficiency of ARGs (i.e., plasmid-mediated floR, sul1, and sul2) with TiO-modified PVDF membrane reached ∼98% after exposure to UV irradiation. Photocatalytic degradation of ARGs located in the genome was found to be more efficient than those located in plasmid. Excellent removal of integrons (i.e., intI1, intI2, and intI3) after UV treatment indicated that the horizontal transfer potential of ARGs was effectively controlled by the TiO photocatalytic reaction. We also evaluated the antifouling properties of the TiO-UF membrane to demonstrate its potential application in wastewater treatment.

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To combat the spread of antibiotic resistance into the environment, we should adequately manage wastewater effluent treatment to achieve simultaneous removal of antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistance genes (ARGs). Herein, we fabricate a multifunctional electroactive poly­(vinylidene fluoride) ultrafiltration membrane (C/PVDF) by phase inversion on conductive carbon cloth. The membrane possesses not only excellent retention toward ARB and ARGs but also exhibits high oxidation capacity as an electrode. Notably, sulfamethoxazole degradation involving hydroxylation and hydrolysis by the anode membrane is predominant, and the degradation efficiency is up to 81.5% at +4 V. Both electro-filtration processes exhibit significant ARB inactivation, anode filtration is superior to cathode filtration. Moreover, the degradation of intracellular ARGs (iARGs) located in the genome is more efficient than those located in the plasmid, and these degradation efficiencies at −2 V are higher than +2 V. The degradation efficiencies of extracellular ARGs (eARGs) are opposite and are lower than iARGs. Compared with regular filtration, the normalized flux of electroactive ultrafiltration membrane is improved by 18.0% at −2 V, 15.9% at +2 V, and 30.4% at +4 V during treating wastewater effluent, confirming its antifouling properties and feasibility for practical application.

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Biofouling is a multifaceted and unavoidable problem in the application of membrane separation technology. Here, we functionalized polyvinylidene fluoride (PVDF) ultrafiltration membranes with poly­(ionic liquid) (PIL) brushes to provide them with antibiofouling properties. The PIL brush grafted membranes (PIL-M) were prepared via atom transfer radical polymerization (ATRP) using different ionic liquids (ILs) on the membrane surface. Four functionalized membranes with different alkyl chain lengths (C4-M, C8-M, C12-M, and C16-M) were prepared to explore the relationship between surface structure and antibacterial properties. Our results showed that all of the PIL-M had antibacterial capabilities with the highest efficiency of 84.6% for the C12-M. Moreover, the antibacterial performance was improved by increasing the ATRP reaction temperature and time. Liposome vesicles were used as the bacterial cell membrane model to evaluate the antibacterial membrane damage mechanism. IL and PIL brushes could damage cell membranes through disrupting the lipid bilayer with longer alkyl chains associated with an enhanced effect. Zeta potential measurements showed that the interference of electrostatic interactions with bacteria also played an important role in the bactericidal mechanism. Moreover, filtration experiments in a cross-flow system further indicated that PIL-M membranes have favorable antibiofouling performance, with a stable flux increase 41.7% larger than that of the pristine PVDF membrane. Our results suggest that functionalization of the membrane surface with the PIL brushes can effectively resist bacteria and thereby significantly mitigate biofouling on the PVDF membranes.