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Though the forward osmosis (FO) process has been primarily accepted for desalination and wastewater treatment, it still faces significant challenges of (i) low water flux and high reverse solute flux and (ii) membrane fouling. In the present study, a new thin film composite (TFC) FO membrane was prepared by interfacial polymerization of chitosan biopolymer and trimesoyl chloride (TMC) as a separation layer and porous CuBTC MOF embedded polyethersulfone (PES) as the support layer to increase transport and antifouling properties. When compared to the bare membrane (J w : 26 LMH, J s : 0.12 GMH) and similar literature reported membranes, the optimized FO membrane with 0.5 wt % CuBTC (Cu@FO-0.5) exhibits higher water flux (J w : 58 LMH) with low reverse salt flux (J s : 0.57 GMH). This improvement is due to the additional pathways for water transportation due to CuBTC MOF. The modified membrane also had a reduced structural parameter (S), a lower reverse salt flux, and increased water wettability. Various physical and chemical membrane cleaning agents were studied to eliminate organic (algae) and inorganic (clay) foulants added to synthetic feed wastewater. The selected cleaning agents were later studied in series and in combinations for both foulants. Chemical cleaning showed higher water flux recovery than physical cleaning and obtained similar results for water collected from natural sources (river, reservoir, and pond). The findings suggest that Cu@FO-0.5 FO membranes integrated with reverse osmosis could be an effective technology in treating drinking water and wastewater sources. [Display omitted] • CuBTC-MOF based thin film composite membrane was prepared. • The forward osmosis membrane showed high water flux and solute rejection. • The CuBTC in FO membrane provided addition pathways for water transportation. • The FO membrane showed resistance to organic and inorganic foulants. [ABSTRACT FROM AUTHOR]

Ultra-low-pressure membrane (ULPM) filtration has emerged as a promising decentralized water and wastewater treatment method. It has been proven effective in long-term filtration under stable flux without requiring physical or chemical cleaning, despite operating at considerably lower flux. The use of ultra-low pressure, often simply by hydrostatic force (often called gravity-driven membrane (GDM) filtration), makes it fall into the uncharted territory of common pressure-driven membrane filtration. The applied polymeric membrane is sensitive to compaction, wetting, and fouling. This paper reviews recent studies on membrane compaction, wetting, and fouling. The scope of this review includes studies on those phenomena in the ULPM and how they affect the overall performance of the system. The performance of GDM systems for water and wastewater treatment is also evaluated. Finally, perspectives on the future research direction of ULPM filtration are also detailed. [ABSTRACT FROM AUTHOR]

Membrane-based processes are a promising technology in water and wastewater treatments, to supply clean and secure water. However, during membrane filtration, biofouling phenomena severely hamper the performance, leading to permanent detrimental impacts. Moreover, regular chemical cleaning is ineffective in the long-run for overcoming biofouling, because it weakens the membrane structure. Therefore, the development of a membrane material with superior anti-biofouling performance is seen as an attractive option. Hydrophilic-anti-bacterial precursor polyethylene glycol-silver nanoparticles (PEG-AgNPs) were synthesized in this study, using a sol-gel method, to mitigate biofouling on the polyethersulfone (PES) membrane surface. The functionalization of the PEG-AgNP hybrid material on a PES membrane was achieved through a simple blending technique. The PES/PEG-AgNP membrane was manufactured via the non-solvent induced phase separation method. The anti-biofouling performance was experimentally measured as the flux recovery ratio (FRR) of the prepared membrane, before and after incubation in E. coli culture for 48 h. Nanomaterial characterization confirmed that the PEG-AgNPs had hydrophilic-anti-bacterial properties. The substantial improvements in membrane performance after adding PEG-AgNPs were evaluated in terms of the water flux and FRR after the membranes experienced biofouling. The results showed that the PEG-AgNPs significantly increased the water flux of the PES membrane, from 2.87 L·m−2·h−1 to 172.84 L·m−2·h−1. The anti-biofouling performance of the PES pristine membrane used as a benchmark showed only 1% FRR, due to severe biofouling. In contrast, the incorporation of PEG-AgNPs in the PES membrane decreased live bacteria by 98%. It enhanced the FRR of anti-biofouling up to 79%, higher than the PES/PEG and PES/Ag membranes. [ABSTRACT FROM AUTHOR]

The type and properties of the filtration solution affect the formation and thickness of the cake layer on the membrane surface. This study aims to identify the effect of the acidity of Sodium Alginate (SA) solution on the filtration profile and cake layer formation on the Polyethersulfone/Aerosol OT (PES/A-OT) membrane surface. The filtration process was carried out using a single hollow fiber module by the pressure-driven outside system with the feed flowing from the membrane's outer wall and clean water collected on the inside of the hollow fiber membrane. The pH solution was tested at neutral, acid, and bases, and the filtration performance of the membrane was evaluated based on water flux recovery ratio (FRR) and cake formation on the membrane surface. The results showed that SA solution with neutral pH produced the best FRR (up to 87.3%) and the thinnest cake layer formation. [ABSTRACT FROM AUTHOR]

The synergistic magnetic interaction between biofunctionalized magnetic nanoparticles and a hybrid membrane is exploited to develop a nano-inspired, magnetic-responsive enzyme membrane (micro) reactor. The novelty of the process lies in the use of superparamagnetic nanoparticles both as enzyme carrier to form bionanocomposites and as nanofiller to form organic–inorganic (O/I) hybrid membrane to render both reversibly magnetizable. This reversible magnetic force facilitates dispersion of the enzymatically active magnetic nanoparticles (bionanocomposites) over the membrane surface, allows retention of the enzyme by a large pore, i.e., high-flux membrane and renders enzyme recovery after use is very easy. The feasibility and versatility of the concept is demonstrated through 2 case studies, i.e., a pectin/polygalacturonase and an arabinoxylan/xylanase system, for membrane fouling prevention through in-situ enzymatic membrane cleaning. This robust multidisciplinary approach resulted in a 75% reduction in filtration resistance, thus realizing significant energy savings and high reactor productivity. The advantages of the novel approach include: (i) absence of need for neither functionalized nor retentive membrane surfaces, (ii) no leakage of nanosized, high surface area immobilized enzymes through microporous membranes, (iii) full recovery and re-usability of the enzymes, (iv) possibility to apply enzyme cocktails to achieve optimal conversions and (v) use of the membrane beyond the enzyme life cycle. [ABSTRACT FROM AUTHOR]

Membrane fouling remains a major obstacle in liquid-based membrane processes, which restricts widespread applications of membrane-based processes. Approaches for membrane fouling control have been reported, including development of spacers. Typically, a spacer is required to provide a flow channel for the feed and permeate, to induce local mixing, and more recently to facilitate membrane fouling control. Those critical roles of a spacer could be enhanced by improving spacer design and geometry as discussed in the present paper. This study provides a comprehensive review on recent development of spacers incorporated in the plate-and-frame as well as in the spiral wound modules (SWMs), particularly on the spacer roles in membrane fouling control. The hydraulic performances of filtration systems incorporating new spacer along with the spacer's impacts against biofouling are extensively discussed. Lastly, perspective on the future development of spacer in aiding membrane fouling control has also been proposed. Research results demonstrated the possibility to modify spacer geometry – more recently – made from 3D printing to enhance the module throughput. The spacer geometry has been modified to reduce pressure loss, improve local mixing and promote turbulence, and to reduce dead zones. Application of new spacer geometries with reduced stagnation zone and coating of spacer surface with biocide agent have shown effective in reducing the propensity of biofouling. In the plate-and-frame module, spacers have successfully been used to enhance air bubble distribution in liquid/gas streams, promote turbulence as well as projecting the air bubbles toward the membrane surface for effective membrane cleaning. [Display omitted] • Progresses in spacer's development of membrane modules are reviewed. • Modified SWM spacers pose low pressure loss and improved turbulence. • Spacers with homogeneous velocity and coated with biocide pose lower biofouling. • Spacer in plate-and-frame module project and distributes air bubbles, or promotes mixing. • Multitude of engineering approach is seen as future strategy for spacer developments. [ABSTRACT FROM AUTHOR]

Membrane bioreactors (MBRs) are established technology for treatment of domestic and industrial wastewater because they offer a small footprint and high quality of effluent, in addition to lower excess sludge. However, their widespread applications are still limited by higher expenditure for compensating for membrane fouling. In this study, polysulfone (PSF)-based ultrafiltration membranes were developed and integrated with a tilted panel system for fouling control in activated sludge filtration. The results show an enhanced performance of filtration system thanks to the mutual advantage of the tilted panel system and the membrane properties. Both membranes showed a clear trend of higher permeability with respect to the tilted panel parameters, namely, higher tilting angle, higher aeration rate, and shorter intermittent/switching period. PSF-1 (1 wt% polyethylene glycol (PEG) additive) shows significantly better performance than PSF-3 (3 wt% PEG additive) although their mean flow pore size, structural properties, and contact angle do not differ significantly. PSF-1 shows superior filterability performance of about 45% for panel tilting angles of 20° at an aeration rate of 1.8 L·min−1, and 11% for a switching period of 1 min compared with PSF-3. The key property enhancing the performance of the PSF-1 is its narrower distribution of pore size. Overall results suggest that an optimum system could be achieved by optimizing both the filtration system and the membrane material properties. [ABSTRACT FROM AUTHOR]

Membrane fouling is seen as the main culprit that hinders the widespread of membrane application in liquid-based filtration. Therefore, fouling management is key for the successful implementation of membrane processes, and it is done across all magnitudes. For optimum operation, membrane developments and surface modifications have largely been reported, including membrane surface patterning. Membrane surface patterning involves structural modification of the membrane surface to induce secondary flow due to eddies, which mitigate foulant agglomeration and increase the effective surface area for improved permeance and antifouling properties. This paper reviews surface patterning approaches used for fouling mitigation in water and wastewater treatments. The focus is given on the pattern formation methods and their effect on overall process performances. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Anaerobic membrane bioreactor technology for biohydrogen production is overviewed. • Enhancement of biohydrogen yield and generation rates via various strategies is discussed. • Techno-economic and environmental impacts of this approach are addressed. Abstract Biohydrogen as one of the most appealing energy vector for the future represents attractive avenue in alternative energy research. Recently, variety of biohydrogen production pathways has been suggested to improve the key features of the process. Nevertheless, researches are still needed to overcome remaining barriers to practical applications such as low yields and production rates. Considering practicality aspects, this review emphasized on anaerobic membrane bioreactors (AnMBRs) for biological hydrogen production. Recent advances and emerging issues associated with biohydrogen generation in AnMBR technology are critically discussed. Several techniques are highlighted that are aimed at overcoming these barriers. Moreover, environmental and economical potentials along with future research perspectives are addressed to drive biohydrogen technology towards practicality and economical-feasibility. [ABSTRACT FROM AUTHOR]

• PW handling with conventional technologies is compared with MD highlighting constraints. • Advances in energy sourcing for MD incorporating solar energy, waste heat and microwave heating. • More insight on fouling and mitigation strategies peculiar to MD of PW. • Competitiveness of MD as an alternative for desalination of PW amidst environmental concern. • Beneficial reuse of PW for irrigation agriculture. Membrane distillation (MD) has proved worthwhile in treatment of hypersaline feeds demonstrating near complete rejection of dissolved solutes without any effect on the process conditions. This makes it potential treatment option for hypersaline oilfield produced water (PW) with salinity level far greater than that of seawater. Polymeric membranes have recently garnered more attention than their ceramic counterparts in oily wastewater treatment owing to ease of synthesis and relative cost advantage. However, lower mechanical durability and the propensity for fouling of these membranes due to presence of low surface energy organics in PW ultimately affects MD performance in its treatment. Studies elucidating the mechanism of fouling between PW feed and membranes in MD is scarcely reported in the literature. Various fouling mitigation approaches have shown promise towards the realization of MD as a viable option for PW treatment. Hybridization of MD, use of (super)hydrophobic MD membranes with feed pre-treatment using other technologies and/or membrane post-cleaning, integrated MD systems and recently omniphobic and Janus modifications of MD membranes have all been reported for treatment of PW showing more promise towards achieving ultrapure-distillate treatment. In this article, the performance of these polymeric MD membranes used in PW treatment in comparison to the other conventional treatment options as well as advances in MD as a cost-effective alternative for beneficial re-use of PW is reviewed, highlighting the areas requiring further study for this line of research. Because MD is still largely energy inefficient, several efforts to realize it as an all-round competitive technology focusing on long-term stability, brine handling capacity and potentials for cost savings with alternative and rather sustainable energy source are also discussed. [ABSTRACT FROM AUTHOR]