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Membrane filtration processes have been widely applied in water and wastewater treatment for many decades. Concerns related to membrane treatment effectiveness, membrane lifespan, and membrane fouling control have been paid great attention. To achieve sustainable membrane operation with regards to low energy and maintenance cost, monitoring membrane performance and applying suitable membrane control strategies are required. As the most abundant species in water and wastewater, bacteriophages have shown great potential to be employed in membrane processes as (1) indicators to assess membrane performance considering their similar properties to human pathogenic waterborne viruses; (2) surrogate particles to monitor membrane integrity due to their nano-sized nature; and (3) biological agents to alleviate membrane fouling because of their antimicrobial properties. This study aims to provide a comprehensive review on the roles of bacteriophages in membrane-based water and wastewater treatment processes, with focuses on their uses for membrane performance examination, membrane integrity monitoring, and membrane biofouling control. The advantages, limitations, and influencing factors for bacteriophage-based applications are reported. Finally, the challenges and prospects of bacteriophage-based applications in membrane processes for water treatment are highlighted. [ABSTRACT FROM AUTHOR]

This study provides a novel method to enhance boron removal in a forward osmosis (FO) process. It utilizes the reverse solute diffusion (RSD) of ions from alkaline draw solutions (DSs) and the concentration polarization of the hydroxyl ions to create a highly alkaline environment near the membrane active surface. The results show that boron rejection can be significantly enhanced by increasing the pH of NaCl DS to 12.5 in the active-layer-facing-feed-solution (AL-FS) orientation. The effect of RSD enhanced boron rejection was further promoted in the presence of concentration polarization (e.g., in the active-layer-facing-draw-solution (AL-DS) orientation). The current study opens a new dimension for controlling contaminant removal by FO using tailored DS chemistry, where the RSD-induced localized water chemistry change is taken advantage in contrast to the conventional method of chemical dosing to the bulk feed water. [ABSTRACT FROM AUTHOR]

Abstract: A novel carbon-sensitized and nitrogen-doped TiO2 (C/N–TiO2) was synthesized by a facile sol-gel method using titanium butoxide as both titanium precursor and carbon source, and nitric acid as nitrogen source. The calcination temperature had a great effect on the crystal phase structure, nitrogen incorporation into the TiO2 lattice and content of carbonaceous species. The incorporated carbonaceous species could serve as photosensitizer, while the nitrogen doping could lead to the remarkable red shift of absorption edge of C/N–TiO2. The C/N–TiO2 calcinated at 300 °C (T300) exhibited the highest photocatalytic activity for sulfanilamide (SNM) degradation under irradiation of visible-light-emitting diode (vis-LED). The SNM photocatalytic degradation and mineralization were more efficient in acidic conditions due to the carbon photosensitizing effect. Insignificant inhibitory effects were observed in the presence of chloride, nitrate and sulfate, while bicarbonate, phosphate and silica could inhibit the SNM mineralization to different degrees. Acetate, ammonium and sulfate were released during SNM mineralization. T300 exhibited good photochemical stability and could be reused for 5 times with less than 10% decrease in the SNM removal efficiency. The acute toxicity of SNM solution could be reduced over prolonged photocatalysis according to the Microtox assay. [Copyright &y& Elsevier]

Abstract In this work, nano-bimetallic Co/Fe oxides with different stoichiometric Co/Fe ratios were prepared using a novel one-step solution combustion method. The nano-bimetallic Co/Fe oxides were used for sulfamethoxazole (SMX) degradation via peroxymonosulfate (PMS) activation. The stoichiometric efficiencies of the as-prepared nano-bimetallic catalysts were calculated and compared for the first time. The radical generation was identified by electron paramagnetic resonance (EPR) as well as chemical quenching experiments, in which different scavengers were used and compared. The catalytic PMS activation mechanism in the presence of catalyst was examined by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results showed that besides SO 4 •- and •OH, •OOH was also detected in the PMS/CoFeO 2.5 system. Meanwhile, in addition to the previously proposed radical oxidation pathway, the results showed that SMX degradation also involved a non-radical oxidation, which could be verified by the degradation experiment without catalyst as well as the detection of 1O 2. In the PMS activation process, cobalt functioned as the active site on CoFeO 2.5 while Fe oxide functioned as the adsorption site. The electron transfer mechanism was proposed based on the XPS and metal leaching results. Additionally, via the detection of transformation products, different SMX transformation pathways involving nitration, hydroxylation and hydrolysis in the PMS/CoFeO 2.5 system were proposed. Graphical abstract Image 1 Highlights • Nano-bimetallic oxides were prepared via one-step solution combustion method. • Stoichiometric efficiencies of nano-bimetallic oxides were calculated. • Radical generation process in PMS/catalyst/SMX system was examined. • SMX transformation pathway in PMS/catalyst/SMX system was proposed. • PMS activation mechanism via nano-bimetallic oxides was investigated. [ABSTRACT FROM AUTHOR]

• SedaDNA metabarcoding revealed cyanobacterial community over past ∼100 years. • A steady increase in toxic cyanobacteria during past 30 years in Lake Taihu. • Climatic warming explains the increasing trend of toxic cyanobacteria. • Recent climate change is exacerbating the harmful effects of toxic cyanobacteria. Cyanobacterial blooms in freshwater systems are a global threat to human and aquatic ecosystem health, exhibiting particularly harmful effects when toxin-producing taxa are present. While climatic change and nutrient over-enrichment control the global expansion of total cyanobacterial blooms, it remains unknown to what extent this expansion reflected cyanobacterial assemblage due to the scarcity of long-term monitoring data. Here we use high-throughput sequencing of sedimentary DNA to track ∼100 years of changes in cyanobacterial community in hyper-eutrophic Lake Taihu, China's third largest freshwater lake and the key water source for ∼30 million people. A steady increase in the abundance of Microcystis (as potential toxin producers) during the past thirty years was correlated with increasing temperatures and declining wind speeds, but not with temporal trends in lakewater nutrient concentrations, highlighting recent climate effects on potentially increasing toxin-producing taxa. The socio-environmental repercussions of these findings are worrisome as continued anthropogenic climate change may counteract nutrient amelioration efforts in this critical freshwater resource. [Display omitted] [ABSTRACT FROM AUTHOR]

Recent studies report high concentrations of haloacetic acids (HAAs), a prevalent class of toxic disinfection by-products, in swimming pool water (SPW). We investigated the removal of 9 HAAs by four commercial reverse osmosis (RO) and nanofiltration (NF) membranes. Under typical SPW conditions (pH 7.5 and 50 mM ionic strength), HAA rejections were >60% for NF270 with molecular weight cut-off (MWCO) equal to 266 Da and equal or higher than 90% for XLE, NF90 and SB50 with MWCOs of 96, 118 and 152 Da, respectively, as a result of the combined effects of size exclusion and charge repulsion. We further included 7 neutral hydrophilic surrogates as molecular probes to resolve the rejection mechanisms. In the absence of strong electrostatic interaction (e.g., pH 3.5), the rejection data of HAAs and surrogates by various membranes fall onto an identical size-exclusion (SE) curve when plotted against the relative-size parameter, i.e., the ratio of molecular radius over membrane pore radius. The independence of this SE curve on molecular structures and membrane properties reveals that the relative-size parameter is a more fundamental SE descriptor compared to molecular weight. An effective molecular size with the Stokes radius accounting for size exclusion and the Debye length accounting for electrostatic interaction was further used to evaluate the rejection. The current study provides valuable insights on the rejection of trace contaminants by RO/NF membranes. [ABSTRACT FROM AUTHOR]

We investigated the removal of haloacetic acids (HAAs) from swimming pool waters (SPWs) by two nanofiltration membranes NF270 and NF90. The strong matrix effect (particularly by Ca 2+ ) on membrane rejection prompts us to systematically investigate the mechanistic role of Ca 2+ in HAA rejection. At typical SPW pH of 7.5, NF90 maintained consistently high rejection of HAAs (>95%) with little influence by Ca 2+ , thanks to the dominance of size exclusion effect for this tight membrane (pore radius ∼ 0.31 nm). In contrast, the rejections of both inorganic ions (e.g., Na + and Cl − ) and HAA anions were decreased at higher Ca 2+ concentration for NF270 (pore radius ∼ 0.40 nm). Further tests show that the rejection of neutral hydrophilic molecular probes and the membrane pore size were not affected by Ca 2+ . Although Ca 2+ is unable to form strong complex with HAAs, we observed the binding of Ca 2+ to NF270 together with a reduction in its surface charge. Therefore, the formation of membrane-Ca 2+ complex, which weakens charge interaction effect, was responsible for the reduced HAA rejection. The current study reveals important mechanistic insights of the matrix effect on trace contaminant rejection, which is critical for a better understanding of their fate and removal in membrane-based treatment. [ABSTRACT FROM AUTHOR]

• Thermo-responsive amphiphilic copolymers show high feasibility as FO draw solute. • Key properties of the copolymers used as draw solute strongly depend on their PEO segments. • The copolymers demonstrate a great stability after multiple cycles of regeneration. • Pluronic® L35 DS at 65% can concentrate a SWRO brine at a FO flux of 1.22 L m‒2 h‒1. • Copolymer induced fouling shows insignificant effect on FO with high-salinity feeds. Recently, thermo-responsive nonionic amphiphilic copolymers have shown a great potential as forward osmosis (FO) draw solutes for high-salinity water desalination and zero-liquid discharge (ZLD). However, the relationship between the copolymer structural properties and key characteristics as draw solutes, as well as copolymer's chemical stability after regeneration have not been much studied. In this work, we systematically investigated poly (ethylene oxide)- block -poly (propylene oxide)- block -poly (ethylene oxide) (PEO-PPO-PEO) copolymers as draw solute. The results showed that the PEO segments significantly influenced the viscosity, osmotic pressure and lowest phase separation temperature of the copolymer aqueous solutions. Among four commercial copolymers studied, Pluronic® L35 with moderate molecular weight (Mn 1,900 Da), 50% PEO, and relatively high hydrophilic-lipophilic balance (HLB) showed the best draw solution (DS) performance. It also showed great stability in physiochemical properties and draw capacity after more than ten cycles of regeneration. On the other hand, despite the fact that membrane fouling was observed due to the use of copolymer DS, the FO flux (∼1.2 L m‒2 h‒1, as similar with the virgin membrane) was not affected when high-salinity feedwater such as seawater RO brine was applied. Overall, our study has provided a more comprehensive understanding on the characteristics of nonionic amphiphilic copolymer DS and showcased the promise of copolymer-driven FO process in high-salinity water desalination and ZLD. [Display omitted]. [ABSTRACT FROM AUTHOR]

A total of 21 progestagens were screened in animal wastes and environmental samples from two representative swine farms and surrounding environments of South China using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) to assess the effectiveness of simple lagoon (and digester) treatment. The results showed that 11, 8 and 8 of 21 target progestagens were detected with the minimum concentration of 2.31 ng/L and maximum of 6150 ng/L in the water samples, with the minimum of 1.36 ng/L and maximum of 98.3 ng/L in the suspended particles, and with the minimum of 1.57 ng/g dry weight (dw) and maximum of 3310 ng/g dw in the solid samples, respectively. Trace levels (a few ng/L or ng/g levels) of dydrogesterone, 5α-dihydroprogesterone, norgestrel and progesterone were found in samples from nearby surface waters and vegetable fields impacted by animal wastes. The residual progestagens at the reported levels may still pose potential risks to aquatic organisms such as fish in the receiving aquatic environments. This finding suggests that swine wastewater and feces could lead to contamination of some detectable progestagens in the surrounding environments. Significant reduction in total progestagen concentrations were observed from the fresh swine wastewaters to the fish ponds, indicating effective removal of these compounds by the lagoon (and digester) treatment. In addition, the biogas digesters provided high removal of the progestagens in the waste streams. This low-cost and eco-friendly treatment system should be promoted in developing countries with concentrated animal operations. [ABSTRACT FROM AUTHOR]

• Biotic homogenization was observed toward high eutrophication for microbes. • Bray-Curtis distance increased with TSI changes, while fungal LCBD declined with TSI. • Eutrophication was a primary driver of microbial community compositions. • Generalists contributed more to β-diversity and were key for biotic homogenization. • LCBD can be considered as a new parameter to indicate homogenization. Eutrophication substantially influences the community structure of aquatic organisms and has become a major threat to biodiversity. However, whether eutrophication is linked to homogenization of microbial communities and the possible underlying mechanisms are poorly understood. Here, we studied bacterial and fungal communities from water and sediments of 40 shallow lakes in the Yangtze-Huaihe River basin, a representative area characterized by intensifying eutrophication in China, and further examined the beta diversity patterns and underlying mechanisms under eutrophication conditions. Our results indicate that eutrophication generally caused biotic homogenization of bacterial and fungal communities in both habitats showing decreased community variations for the sites with a higher trophic state index (TSI). In the two habitats, community dissimilarities were positively correlated with TSI changes for both taxonomic groups, while the local contribution to beta diversity (LCBD) remarkably declined with increasing TSI for the fungal community. These phenomena were consistent with the pivotal importance of the TSI in statistically accounting for beta diversity of bacterial and fungal communities in both habitats. In addition, we found that physicochemical factors such as water temperature and pH were also important for bacterial and fungal communities in water, while heavy metal elements were important for the communities in sediments. Interestingly, generalist species, rather than specialist species, were revealed to more dominantly affect the variations in beta diversity along the trophic gradient, which were quantified by Bray-Curtis dissimilarity and LCBD. Collectively, our findings reveal the importance of generalist species in contributing to the change of beta diversity of microbial communities along trophic gradients, which have profound implications for a comprehensive understanding of the effects of eutrophication on microbial community. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: We report a study to explore new materials and a new concept for temperature driven quasi-continuous desalination using hydrogels as draw agents in forward osmosis (FO). This concept is enabled by the design and preparation of thermally responsive hydrogels having a semi-interpenetrating network (semi-IPN) structure. Thermally responsive semi-IPN hydrogels were synthesized by polymerization of N-isopropylacrylamide (NIPAm) in the presence of polysodium acrylate (PSA) or polyvinyl alcohol (PVA). Their functions as draw agents in FO were systematically studied and compared with hydrogels prepared from the PNIPAm homopolymer or the NIPAM-SA copolymer. While the semi-IPN hydrogels displayed the desirable balanced thermally responsive swelling and dewatering behavior, the NIPAm-SA copolymer hydrogels were found to have poor dewatering behavior, making them unsuitable for a continuous temperature driven desalination process. At 40 °C, the semi-IPN hydrogels rapidly release nearly 100% of the water absorbed during the FO drawing process carried out at room temperature. Results clearly indicate the potential of semi-IPN hydrogels as semi-solid draw agents in the FO process, in which quasi-continuous desalination could be achieved by cyclic heating and cooling within a moderate temperature change. [Copyright &y& Elsevier]

Abstract: This research focused on combined organic–inorganic fouling and cleaning studies of forward osmosis (FO) membranes. Various organic/inorganic model foulants such as sodium alginate, bovine serum albumin (BSA) and silica nanoparticles were applied to polyamide-polyethersulfone FO hollow fiber membranes fabricated in our laboratory. In order to understand all possible interactions, experiments were performed with a single foulant as well as combinations of foulants. Experimental results suggested that the degree of FO membrane fouling could be promoted by synergistic effect of organic foulants, the presence of divalent cations, low cross-flow velocity and high permeation drag force. The water flux of fouled FO hollow fibers could be fully restored by simple physical cleaning. It was also found that hydrodynamic regime played an important role in combined organic–inorganic fouling of FO membranes. [Copyright &y& Elsevier]

• The progress of photothermal membrane distillation (PMD) is reviewed. • PMD mechanisms and membrane requirements are summarized. • Photothermal materials for developing PMD membranes are reviewed. • Diverse approaches to prepare PMD membranes are classified and discussed. • PMD membrane performance and their applications are reviewed and discussed. The conventional membrane distillation (MD) process is accompanied by large energy consumption, low thermal efficiency and inevitable requirements of centralized infrastructures, which impede its practical applications, especially in the offshore and remote off-grid areas. Thanks to the rapid development of efficient photothermal materials over the last decade, a new photothermal membrane distillation (PMD) process has emerged to harness abundant solar energy and localize heating on the membrane-feed water interface via photothermal effects. Driven by the temperature difference across the PMD membrane, water vapor can be generated on the membrane-feed surface, transported through membrane pores and condensed at permeate side to obtain freshwater, thus tackling the challenge of obtaining clean water using green energy. The PMD process avoids heating the entire bulk feed water and feed transportation from heat units to membrane modules, which save substantial amounts of energy. The interfacial localized heating intrinsically mitigates the temperature polarization across the membrane. The latent heat from vapor condensation can be effectively recovered via multi-level PMD configurations. As great efforts have been made to exploit PMD process, it is imperative to review the state-of-the-art progress of PMD and shed light on its future trend. Here, we briefly illustrate PMD mechanisms and membrane requirements, photothermal materials feasible for developing PMD membranes along with their light-to-heat mechanisms. This is followed by reviewing diverse approaches to prepare PMD membranes, which are classified into one-step fabrication and multi-step modification methods. Comprehensive discussion about PMD membrane performance in different configurations and their small pilot-scaled applications are provided. The effects of operational parameters and module designs are discussed in Section 6. Finally, the current challenges and future perspectives of PMD process are emphasized with the aim of providing guidance for future works. [Display omitted] [ABSTRACT FROM AUTHOR]

• Solvent resistant membrane distillation was tested for organic wastewater separation. • Hydrophobic ceramic membranes were obtained through chemical grafting. • The grafted membranes performed excellently in water-dimethyl sulfoxide separation. • Rejection >98% can be achieved for a feed containing <65 wt% dimethyl sulfoxide. • The permeate product can be sent to bioreactor if feed concentration is <20 wt%. The treatment of organic waste or wastewater with high organic solvent content has been challenging in industries as it cannot be done effectively using conventional wastewater treatment technologies such as biodegradation and advanced oxidation process. Solvent resistant membrane distillation (SR-MD) was proposed as an energy-efficient alternative to treat these waste streams but its application is hampered by the lack of solvent-resistant membranes, and there is a research gap in studying the feeds with water-solvent mixtures. In this work, ceramic tubular membranes with different pore sizes and structures were molecularly grafted with 1H,1H,2H,2H-perfluorodecyltriethoxysilane to obtain hydrophobic ceramic membranes for SR-MD. The modified membranes exhibited excellent hydrophobicity and solvent resistant properties, and they were tested for SR-MD performance with a wide range of dimethyl sulfoxide (DMSO) feed concentrations, from 3.5 to 85 wt%. The membranes exhibited a high DMSO rejection of >98% and the separation factor of >170, with permeation flux >4.4 kg m−2 h−1 when the DMSO concentration in feed was below 65 wt%. The separation performance was found strongly dependent on the evaporation step and the vapour-liquid equilibrium near the interface. The DMSO rejection was also comparable to pervaporation while the permeation flux was much higher at the feed concentration of 50 wt%. This study establishes the strategy of using SR-MD as a promising membrane process in treating complex industrial wastes with high organic solvent content. [Display omitted] [ABSTRACT FROM AUTHOR]

A dynamic membrane (DM) is a layer of particles deposited via permeation drag onto a conventional membrane, such that the deposited particles act as a secondary membrane that minimizes fouling of the primary membrane to lower transmembrane pressures (TMP) and enable higher permeate fluxes. Since the first DM was created in 1966 at the Oak Ridge National Laboratory, numerous studies have reported synthesis of DMs using various materials and explored their abilities to perform reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF). DMs are classified into two categories, namely, (i) self-formed, whereby the feed constituents form the DM; and (ii) pre-deposited, whereby the DM is formed by a layer of particles other than the feed prior to introduction of the feed. This paper endeavors to present a comprehensive review of the state-of-the-art on the latter. Key materials used as DMs, their formation and various factors influencing it, regeneration of DMs and modifications to DM systems for performance enhancement are discussed. The role of DMs in preventing fouling in the primary membrane (PM) is explained. The applications of DMs in four major areas, namely, salt and organic solute rejection, treatment of industrial effluents, treatment of water and wastewater, and oily-wastewater treatment are reviewed. Furthermore, technical and economic advantages of DMs over conventional processes are considered, and challenges in current DM research are discussed. Finally, directions for future research are suggested. Image 1 • Comprehensive review of 148 publications on pre-deposited dynamic membranes (DMs). • DM material, support structure, cross-flow velocity and pH affect DM formation. • Metal oxides, polymers and dual metal oxide-polymer layers are most common DMs. • Developed for reverse osmosis, now used in organics removal and fouling mitigation. • Nanoparticles are recent versatile DM materials and promising in fouling mitigation. [ABSTRACT FROM AUTHOR]