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Increasing the surface porosity of a support membrane has been proposed as an effective way to improve the water permeability of thin-film composite (TFC) reverse osmosis (RO) membranes by reducing the diffusion pathway in the active layer. In this work, we prepared a highly porous microstructured (HPμS) support membrane with a suitable mechanical strength to enhance the water permeability of an RO membrane. The HPμS support membrane was prepared by increasing the thermodynamic instability of a 10 wt% polymer solution and thereby facilitating rapid desolvation. The rapid desolvation formed the narrow and regularly arranged pore structure in the sublayer, and we proposed the mechanism for the sublayer structure formation based on analyses of the thermodynamic properties of such a binary system. Owing to the narrow and regular structure, the HPμS support membranes showed the exceptional mechanical strength, which was comparable to the strength of support membranes used for conventional RO membranes. Also, the HPμS support membranes successfully endowed an in-house RO membrane with the performance (water permeability of 4.68 L m −2  h −1  bar −1 and NaCl rejection of 98.3%) surpassing commercial RO membranes and thin-film nanocomposite membranes recently reported in the literature. [ABSTRACT FROM AUTHOR]

Pressure retarded osmosis (PRO) has been identified as a promising technology to harvest the salinity gradient energy. For practical applications of PRO process, membrane fouling is a challenging issue as it leads to severe decline of PRO performance in terms of water flux and power density. It is imperative to develop anti-fouling membranes for PRO process. The current study demonstrated the unique roles and the great potential of aminosilane in developing anti-fouling thin film composite (TFC) PRO membranes. Experimental results revealed that aminosilane as a grafting agent can modify both the support layer (interior) and the selective layer of PRO membranes with remarkably enhanced hydrophilicity via a very simple grafting procedure. In the grafting, aminosilane was able to minimize the pore-blocking issue with almost no increase in the membrane structural parameter ( S ). Meanwhile, the membrane mechanical strength was well maintained with the grafting due to the capability of aminosilane as a cross-linker. With enhanced hydrophilicity, it was interestingly found that the water permeability ( A ) was doubled, while the salt rejection was maintained nearly unchanged. The combination of these effects brought in remarkably enhanced water flux, power density and anti-fouling property to the resultant membrane. [ABSTRACT FROM AUTHOR]

This study focuses on enhancing the mechanical strength of aquaporin (AQP)-based biomimetic membranes for seawater desalination. AQP incorporated vesicles were embedded into the selective layer of an optimized thin film composite (TFC) membrane. The resultant membrane, denoted as ASW, exhibited a stable water flux around 20 L·m−2·h−1 and 99% NaCl rejection at a constant pressure of 55 bar using 32,000 mg·L−1 NaCl solution as feed in reverse osmosis (RO) measurement. The robustness of the ASW membranes were evaluated. The water flux of ASW membrane was almost 100% enhanced compared with that of AQP-free control TFC membranes. The filtration performance of the ASW membrane was further evaluated by a seven-day desalination test using a real seawater secondary effluent collected from a desalination plant in Singapore as feed. To our best knowledge, our study is the first report on the AQP-incorporated RO membrane applied for seawater desalination. A commercial SW30HR membrane was tested in parallel for comparison. The robust ASW membrane exhibited a nearly 80% higher water flux in comparison to the SW30HR membrane with a comparable overall solute rejection, suggesting the advantage and feasibility of Aquaporin based biomimetic membranes for seawater desalination. • The mechanical strength of aquaporin incorporated polyamide layer was characterized with AFM. • The effects of high pressure compaction and salinity on aquaporin incorporated polyamide layer were investigated. • The aquaporin based biomimetic membranes were optimized for seawater desalination (SWRO) application. • A seven-day SWRO measurement of the ASW was conducted using a real seawater secondary effluent. [ABSTRACT FROM AUTHOR]

The ultra-permeable membranes (UPMs) are expected to reduce the specific energy consumption (SEC) of desalination, but the potential of UPMs in hollow fiber configuration has not been well quantified. Herein, we analyse the SEC and footprints of UPM modules in three feed salinities: seawater reverse osmosis (SWRO), brackish water RO (BWRO) and low-pressure RO (LPRO). Through the modelling the fluid dynamics and mass transport of RO systems, we find that a tripling in spiral-wound SWRO membrane permeability (based on the current value of 1 L m−2 h−1 bar−1; LMH/bar) could result in 16% decrease in SEC. Contrastingly, the quadrupling of hollow fiber SWRO membrane permeability (based on the current value of 0.25 LMH/bar) could reduce the SEC by 23%. According to our analysis, hollow fiber and spiral-wound SWRO membranes with permeabilities up to 1 LMH/bar and 3 LMH/bar, respectively, can reduce the SEC of seawater desalination. On the other hand, membranes with permeabilities up to 9 LMH/bar and 12 LMH/bar can lead to SEC savings in BWRO and LPRO desalination, respectively. This study provides a general guidance to RO membrane researchers on the permeability upper-limit of which UPMs could bring about SEC and footprint savings at a system level. [Display omitted] • Energy savings achievable by high permeability RO membranes were quantified. • Modelling was performed by simulating fluid dynamics in various RO configurations. • Hollow fiber SWRO membranes (up to 1 LMH/bar) could reduce energy consumption. • Spiral-wound SWRO membranes (up to 3 LMH/bar) could reduce energy consumption. • High permeability RO membranes could bring about greater benefits in BWRO/LPRO. [ABSTRACT FROM AUTHOR]

Abstract: There has been an increasing interest in the novel integration of forward osmosis (FO) and biological process known as the osmotic membrane bioreactor (OMBR). However, little operating experience is available to adequately assess the feasibility of the technology for larger scale application. The goal of this study is to provide fundamental information on the technology. In this study, an OMBR system was continuously operated for 73days. It was found that the high retention property of the FO membrane and salt transmission from the draw solution resulted in increasing mixed liquor salinity until a stable state was reached. In spite of the elevated salinity, the water flux was relatively stable at around 3Lm−2 h−1. Post-experiment analyses indicated mild membrane fouling, and its effect on water permeability was insignificant. An ion analysis check indicated that scaling did not occur. The SEM examination detected a thin gel-like secondary layer on the membrane surface. It was deduced that this secondary layer could have an influencing role on salt transmission during the experiment, and moderated salt concentration in the bioreactor. [Copyright &y& Elsevier]

In this study, a prototype microgranular adsorptive filtration (μGAF) system was constructed employing a 7-bore ceramic membrane as the primary membrane and either heated aluminum oxide particles (HAOPs) or powdered activated carbon (PAC) as the pre-deposited dynamic membrane (DM). The system was used to pre-treat membrane bioreactor (MBR) effluent from a full-scale MBR-reverse osmosis (RO) water reclamation plant. The downstream RO performance and membrane fouling potential of the treated effluent were then assessed. The results indicated that: (i) although PAC removed more overall EfOM than HAOPs did, HAOPs were more effective in removing biopolymers such as polysaccharides and proteins, (ii) HAOPs virtually eliminated fouling of the primary ceramic membrane, whereas considerable fouling (much of it irreversible) occurred when the feed was pretreated with PAC, (iii) HAOPs removed more than 90% of the phosphorus and fluoride from the feed, but PAC removed negligible amounts of these contaminants, and (iv) HAOPs-treated effluent resulted in only a 43% decline in RO permeate water flux over 5 d of continuous filtration, as opposed to 62% flux decline for untreated or PAC-treated effluent. This study thus demonstrates the effectiveness of the HAOPs-based μGAF process as a pre-treatment for improving downstream RO recovery. • A prototype μGAF system was used to treat an MBR effluent from a full-scale MBR-RO plant. • μGAF using HAOPs demonstrated an efficient removal of biopolymer, phosphorus, silica and fluoride. • HAOPs was more effective at mitigating downstream RO fouling compared to PAC. • HAOPs demonstrated the potential to enhance the overall performance of a water recovery process. [ABSTRACT FROM AUTHOR]

Membrane fouling occurs in all membrane processes. Surface modifications have gained popularity for enhancing membrane antifouling capability via introducing a hydrophilic component or reducing membrane surface roughness. In this work, we proposed to develop a green antimicrobial lysozyme nanofilm on the polyamide membrane surface with remarkable antibacterial and antifouling properties to effectively reduce membrane fouling. The nanofilm is rooted in the molecular assembly of a protein which is an extraction of food and natural products. The nanofilm exhibits the combination of various functions including antimicrobial, antifouling and antibiofilm. This protein-based nanofilm is robustly transferred and self-adhered on the membrane surface by a simple one-step aqueous coating. The modified RO membrane exhibited good performance in bacterial reduction of ~50% in comparison to the control membrane and experienced almost zero loss in water flux and salt rejection under SWRO testing condition. The membrane is further evaluated with real seawater for 14 days and the modified membrane showed its superiority in flux and fouling control which were verified by the confocal laser scanning microscopy (CLSM) and quantified by inductively coupled plasma optical emission spectrometer (ICP-OES). This work demonstrates that the protein-based biomaterials offer a safe and environmentally friendly way of antimicrobials, which can reduce membrane fouling significantly in membrane filtration. Unlabelled Image • A protein-based antimicrobial nanofilm was in-situ fabricated on a commercial SWRO membrane surface. • The modification did not change the SWRO membrane's selectivity and water permeability. • The modified membrane demonstrated ~50% bacterial reduction compared to the control membrane. • The modified membrane had good anti-fouling property applied in SWRO. [ABSTRACT FROM AUTHOR]