Membrane-based Method Research Articles

Optimized ceramic membrane-based method for efficient and acid-free rice protein preparation from alkaline extracts

Rice protein, stands out as a high-quality plant-based protein, suitable for dietary supplementation and food processing. Traditional methods, involving alkaline extraction and acid precipitation, are challenged by the extensive use of chemicals and the difficulty in desalination. This study proposed a novel separation method that utilizes ceramic membranes for direct alkali filtration, eliminating the formation of salts by acid neutralization. The membrane pore size and the operating parameters such as transmembrane pressure, cross-flow velocity, and pH were optimized to enable a high flux (>80 L m−2·h−1) and favorable protein rejection (>95 %) while permitting the removal of excess alkali. Additionally, the effects of non-protein substances, e.g., starch, present in the alkaline extract on the separation performance were explored. Subsequently, an optimized strategy for starch removal was proposed, involving the concentration of the alkali extract using an ultrafiltration membrane, followed by enzymatic hydrolysis of starch and diafiltration to eliminate the residuals of starch hydrolysates and alkali. Under stabilization of protein particles by carboxymethyl cellulose, rice protein with a uniform particle size of 25 nm and a purity of over 80 % was produced. The direct removal of alkali from alkali extracts of rice by ceramic membranes presents a promising strategy for producing rice protein with high purity and reduced aggregation degree, enabling better functionalities such as solubility than the conventional alkali-extraction and acid-precipitation method.

Simulating the Effects of Ammonia Crossover and Alternative Ligands in Thermally Regenerative Flow Batteries

There is a significant amount of low-temperature heat (< 100 °C) available globally from various sources such as geothermal energy, industrial processes, and thermal power plants. Electrochemical and membrane-based methods for harnessing this heat are becoming of greater interest due to their ability to utilize the low temperature energy sources and because they can be sized modularly to fit the power, energy, and spatial requirements of the application. The all-aqueous thermally regenerative ammonia battery (Cuaq-TRAB) is a leading technology in the waste heat to electrical power production space due to recent results showing operational power densities of 25 mW cm-2 with an estimated thermal energy efficiency of 7%, outperforming most technologies in this space. Previous research on the Cuaq-TRAB has shown that the battery suffers from the crossover of ammonia through the membrane which adversely impacts battery performance.To investigate these impacts, we developed a simple numerical model that simulates discharge curves using one fitting parameter to account for parasitic crossover instead of modeling species transport through the membrane. The model was able to replicate experimental data from Cuaq-TRABs with different membrane materials and for multiple applied current densities with < 5% error for average power and energy capacity. Results showed that there is a 20% loss in Cuaq-TRAB energy capacity due to ammonia crossover when compared to a discharge with no parasitic crossover losses. The model was then extended to demonstrate the impact of different changes to the electrolyte chemistry on the resultant power and energy capacities for Cuaq-TRABs. Using this model, we estimate that if chloride was the ligand for the positive electrolyte instead of bromide, it would decrease the power and energy capacity of the battery by 30%. However, considering that an economic analysis showed that chloride is 80% cheaper than bromide, it may be beneficial to consider the use of chloride ligands in this technology despite its worse electrochemical performance.

Lensless shadow microscopy-based shortcut analysis strategy for fast quantification of microplastic fibers released to water

Fast quantification is the primary challenge in monitoring microplastic fiber (MPF) pollution in water. The process of quantifying the number of MPFs in water typically involves filtration, imaging on a filter membrane, and manual counting. However, this routine workflow has limitations in terms of speed and accuracy. Here, we present an alternative analysis strategy based on our high-resolution lensless shadow microscope (LSM) for rapid imaging of MPFs on a chip and modified deep learning algorithms for automatic counting. Our LSM system was equipped with wide field-of-view submicron-pixel imaging sensors (>1 cm2; ∼500 nm/pixel) and could simultaneously capture the projection image of >3-μm microplastic spheres within 90 s. The algorithms enabled accurate classification and detection of the number and length of >10-μm linear and branched MPFs derived from melamine cleaning sponges in each image (∼0.4 gigapixels) within 60 s. Importantly, neither MPF morphology (dispersed or aggregated) nor environmental matrix had a notable impact on the automatic recognition of the MPFs by the algorithms. This new strategy had a detection limit of 10 particles/mL and significantly reduced the time of MPF imaging and counting from several hours with membrane-based methods to just a few minutes per sample. The strategy could be employed to monitor water pollution caused by microplastics if an efficient sample separation and a comprehensive sample image database were available.

Membrane based In-situ reduction of graphene oxide for electrochemical supercapacitor application

Reduced graphene oxide (rGO) is a widely studied electrode material for energy storage, however, its strong re-stacking tendency during chemical reduction always leads to a degraded specific surface area and thus limits its performance. Therefore, it is necessary to control the morphology of rGO during the reduction process. Here, we develop a novel in-situ membrane-based method for the reduction of graphene oxide (GO) using a green and efficient vitamin C (VC) aqueous solution as reductant. The obtained electrode material (vitamin C reduced GO via membrane-based method, VG-M) exhibits a specific capacitance of 174 F/g at 1 A/g and 75.9% of retention at 40 A/g, which is about 9 times better than the highly self-stacked material from conventional methods (vitamin C reduced GO via stirring method, VG-S). This designed method successfully achieves the maintenance of rGO sheet morphology through laminar confinement in GO membrane and presents a simple approach towards two-dimensional (2D) material morphology control.

Comparative RNA isolation methods from fresh ejaculated spermatozoa in Sahiwal cattle (Bos indicus) and Murrah buffalo (Bubalus bubalis) bulls for high quality and enhanced RNA yield

Sperm mRNA transcriptional profiling can be used to evaluate the fertility of breeding bulls. The aim of the study was to compare the modified RNA isolation methods for higher RNA yield and quality from freshly ejaculated sperm of cattle and buffalo bulls. Ten fresh ejaculates from each Sahiwal (n = 10 bulls × 10 ejaculates) and Murrah bulls (n = 10 bulls x 10 ejaculates) were used for RNA isolation. From the recovered live sperm, total sperm RNA was isolated by conventional methods (TRIzol, Double TRIzol), membrane-based methods combined with TRIzol (RNeasy + TRIzol) with the addition of β-mercaptoethanol (BME) and Kit (RNeasy mini) methods in fresh semen. Among different isolation methods; the membrane-based modified methods combined with TRIzol (RNeasy + TRIzol) with the addition of β-mercaptoethanol (BME) resulted significantly (p < .05) higher total RNA quantity (300–340 ng/µL) and better purity in different concentrations of spermatozoa viz., 30–40 million, 70–80 million and 300–400 million sperm. The study concluded that the inclusion of BME to the combined membrane-based methods with somatic cell lysis buffer solution was best for constant increased yield and purity of RNA isolation from Sahiwal cattle and Murrah buffalo bull sperm.

Polysaccharide nanocomposites in wastewater treatment: A review

In modern times, wastewater treatment is vital due to increased water contamination arising from pollutants such as nutrients, pathogens, heavy metals, and pharmaceutical residues. Polysaccharides (PSAs) are natural, renewable, and non-toxic biopolymers used in wastewater treatment in the field of gas separation, liquid filtration, adsorption processes, pervaporation, and proton exchange membranes. Since addition of nanoparticles to PSAs improves their sustainability and strength, nanocomposite PSAs has gained significant attention for wastewater treatment in the past decade. This review presents a comprehensive analysis of PSA-based nanocomposites used for efficient wastewater treatment, focusing on adsorption, photocatalysis, and membrane-based methods. It also discusses potential future applications, challenges, and opportunities in adsorption, filtration, and photocatalysis. Recently, PSAs have shown promise as adsorbents in biological-based systems, effectively removing heavy metals that could hinder microbial activity. Cellulose-mediated adsorbents have successfully removed various pollutants from wastewater, including heavy metals, dyes, oil, organic solvents, pesticides, and pharmaceutical residues. Thus, PSA nanocomposites would support biological processes in wastewater treatment plants. A major concern is the discharge of antibiotic wastes from pharmaceutical industries, posing significant environmental and health risks. PSA-mediated bio-adsorbents, like clay polymeric nanocomposite hydrogel beads, efficiently remove antibiotics from wastewater, ensuring water quality and ecosystem balance. The successful use of PSA-mediated bio-adsorbents in wastewater treatment depends on ongoing research to optimize their application and evaluate their potential environmental impacts. Implementing these eco-friendly adsorbents on a large scale holds great promise in significantly reducing water pollution, safeguarding ecosystems, and protecting human health.

A NitroPure Nitrocellulose Membrane-Based Grapevine Virus Sampling Kit: Development and Deployment to Survey Japanese Vineyards and Nurseries.

We developed a NitroPure Nitrocellulose (NPN) membrane-based method for sampling and storing grapevine sap for grapevine virus detection. We devised an efficient nucleic acid extraction method for the NPN membrane, resulting in 100% amplification success for grapevine leafroll-associated virus 2 (GLRaV2) and 3 (GLRaV3), grapevine rupestris stem pitting-associated virus (GRSPaV), grapevine virus A, grapevine virus B, and grapevine red blotch virus (GRBV). This method also allowed the storage of recoverable nucleic acid for 18 months at room temperature. We created a sampling kit to survey GLRaV2, GLRaV3, and GRBV in Japanese vineyards. We tested the kits in the field in 2018 and then conducted mail-in surveys in 2020-2021. The results showed a substantial prevalence of GLRaV3, with 48.5% of 132 sampled vines being positive. On the other hand, only 3% of samples tested positive for GLRaV2 and none for GRBV.

Adsorption Dynamics of Uremic Toxins to Novel Modified Magnetic Nanoparticles.

Kidney dysfunction leads to the retention of metabolites in the blood compartment, some of which reach toxic levels. Uremic toxins are associated with the progression of kidney disease and other symptoms of kidney failure (i.e., nausea, itchiness, and hypertension). Toxin removal ameliorates symptoms and reduces further organ damage, but membrane-based methods are inadequate for this purpose. Engineered adsorbents may facilitate enhanced removal of retained toxins, especially those bound strongly by proteins. Poly 2-(methacryloyloxy)ethyl phosphorylcholine-co-β-cyclodextrin (p(MPC-co-PMβCD)) coated magnetic nanoparticles are synthesized, characterized for their physicochemical properties (Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis(TGA), gel permeation chromatography(GPC), and transmission electron microscope (TEM), and evaluated toxin adsorption from a complex solution for the first time to quantify the effects of film chemistry and incubation time on the adsorbed toxinome (the collection of toxins). Uremic toxins are bound by even "low-fouling" polymer films themselves; providing further insight into how small molecule interactions with "low-fouling" films may affect protein-surface interactions. These results suggest a dynamic interaction between toxins and surfaces that is not driven by solution concentration alone. This knowledge will help advance the design of novel adsorbent films for clearing uremic toxins.

Generation and Influence of Carbon Dioxide Nanobubbles on Physicochemical Properties Including the Surface Tension of Clarified Apple Juice

AbstractThis work aims at examining the impact of generated CO2 nanobubbles (NBs) via the membrane-based method on physicochemical properties and surface tension of commercial clarified apple juice. The gas was injected at 300 kPa pressure for variable liquid circulation times (5, 13 and 26 min) to produce the CO2 NBs. Sets of 13- and 26-min circulation time to mix CO2 and liquid gave the desirably nano-size (~ 80–200 nm) NBs and significantly (p ≤ 0.05) reduced surface tension (by ~ 20–25%) of the juice dispersed with these formed tiny gas bubbles (NB-juice). An increase in circulation time also resulted in more negative zeta potential and higher dissolved CO2 concentration of the NB-juice. Density values of apple juice remained unchanged with and without incorporating CO2 NBs. These experimental outcomes provide the potential use of NBs in controlling the characteristics of liquid food as an environment-friendly approach to minimise chemical usages.

A Review of Microfiltration Membrane in Separating Folic Acid from Fermented Dark Green Leafy Vegetables (DGLVs), Legumes, Beans, and Cereal for Nutraceutical Application

DGLVs (spinach, broccoli), legumes (soybean, mung bean, kidney bean), and cereal (corn) are well recognized for human health benefits due to the presence of natural folate (vitamin B9) with essential micronutrients. Folate is among the most unstable vitamins for the normal functions of the human body. The recent development of membrane-based methods for the separation of folic acid (FA) is reviewed from the selected literature and covers the result of significant research that has been performed in the last five years on the use of the microfiltration (MF) method. This is coupled with the fermentation process to support and achieve separation or recovery of FA from their selected plant-based food source. The nixtamalization, fermentation, separation, and purification of DGLVs, legumes, and beans, as well as corn, were conducted using the MF (pore size 0.15 µm) membrane separation method. The results showed that the MF membrane was able to separate FA components in permeate from fermented spinach and broccoli, soybean, mung bean, kidney bean, and corn, namely 7.14 and 3.79, 197.00, 325.37 and 242.93, and 121.10 µg/mL, respectively. Meanwhile, FA content in retentate from fermented spinach and broccoli, soybean, mung bean, kidney bean, and corn was 58.90 and 28.10, 362.07, 254.07 and 506.07, and 212.84 µg/mL, respectively. The applications of membrane techniques were used as an alternative to some unit operations in the solving of separation issues as well as the development of selected new fermented plant-based food sources. The contemporary pressure-driven membranes, such as MF, and the main applications were related to pre-treatment, selected fermented plant-based food sources, and alternative technology for extending the shelf life of natural folate. The utilization of MF membranes in the nutraceutical field holds significant promise, particularly in the creation of value-added products from minor compounds.

Harvesting Blue Energy Based on Salinity and Temperature Gradient: Challenges, Solutions, and Opportunities.

Greenhouse gas emissions associated with power generation from fossil fuel combustion account for 25% of global emissions and, thus, contribute greatly to climate change. Renewable energy sources, like wind and solar, have reached a mature stage, with costs aligning with those of fossil fuel-derived power but suffer from the challenge of intermittency due to the variability of wind and sunlight. This study aims to explore the viability of salinity gradient power, or "blue energy", as a clean, renewable source of uninterrupted, base-load power generation. Harnessing the salinity gradient energy from river estuaries worldwide could meet a substantial portion of the global electricity demand (approximately 7%). Pressure retarded osmosis (PRO) and reverse electrodialysis (RED) are more prominent technologies for blue energy harvesting, whereas thermo-osmotic energy conversion (TOEC) is emerging with new promise. This review scrutinizes the obstacles encountered in developing osmotic power generation using membrane-based methods and presents potential solutions to overcome challenges in practical applications. While certain strategies have shown promise in addressing some of these obstacles, further research is still required to enhance the energy efficiency and feasibility of membrane-based processes, enabling their large-scale implementation in osmotic energy harvesting.

Development and validation of most efficient RNA isolation method from buffalo bull spermatozoa.

Being highly fragmented and low in concentration, isolation of good quality RNA from sperm cells is a big challenge. Attempts have been made to evaluate various sperm RNA isolation methods from purified buffalo bull sperm cells. Both, non-membrane and membrane-based methods have been evaluated for isolating RNA from Murrah buffalo sperms and compared for their respective efficacies. The traditional TRIzol, TRIzol-heat lysed (H-TRIzol) and cocktail of TCEP-RLT lysis buffer (Qiagen RNeasy mini kit)-TRIzol (C-TRIzol) based isopropanol isolation methods have been evaluated. H-TRIzol yielded best results among conventional methods. The combined T-RLT RNA isolation protocol yielded best quality and quantity compared to other membrane-based methods, due to high lytic property of cocktail of lysis reagents, necessary for complete breakdown of sperm membrane and RNA binding membrane for RNA isolation. Combined lysis performed by treatment with RLT-T and T-RLT differing in order of reagents used were also evaluated. T-RLT combination giving better results compared to RLT-T due to high gDNA contamination and membrane clogging in later protocol steps. Overall, in terms of total RNA quantity and quality per million spermatozoa, the heat-lysed TRIzol method (H-TRIzol) performs best among RNA separation techniques employed and is also quite easy to perform. This comparative evaluation of sperm RNA isolation protocols can be useful in deciding the best protocol for isolation of good quality and high concentration sperm RNA from buffalo semen, for transcriptome and other downstream studies.

Rapid Quantitation of Various Therapeutic Monoclonal Antibodies Using Membranes with Fc-Specific Ligands.

Therapeutic monoclonal antibodies (mAbs) provide effective treatments for many diseases, including cancer, autoimmune disorders, and, lately, COVID-19. Monitoring the concentrations of mAbs is important during their production and subsequent processing. This work demonstrates a 5 min quantitation of most human immunoglobulin G (IgG) antibodies through capture of mAbs in membranes modified with ligands that bind to the fragment crystallizable (Fc) region. This enables binding and quantitation of most IgG mAbs. Layer-by-layer (LBL) adsorption of carboxylic acid-rich polyelectrolytes in glass-fiber membranes in 96-well plates allows functionalization of the membranes with Protein A or a peptide, oxidized Fc20 (oFc20), with high affinity for the Fc region of human IgG. mAb capture occurs in <1 min during the flow of solutions through modified membranes, and subsequent binding of a fluorophore-labeled secondary antibody enables quantitation of the captured mAbs using fluorescence. The intra- and inter-plate coefficients of variations (CV) are <10 and 15%, respectively, satisfying the acceptance criteria for many assays. The limit of detection (LOD) of 15 ng/mL is on the high end of commercial enzyme-linked immunosorbent assays (ELISAs) but certainly low enough for monitoring of manufacturing solutions. Importantly, the membrane-based method requires <5 minutes, whereas ELISAs typically take at least 90 min. Membranes functionalized with oFc20 show greater mAb binding and lower LODs than membranes with Protein A. Thus, the membrane-based 96-well-plate assay, which is effective in diluted fermentation broths and in mixtures with cell lysates, is suitable for near-real-time monitoring of the general class of human IgG mAbs during their production.

A novel approach to noninvasive monitoring of dissolved carbon dioxide in small-scale cell culture processes.

Disposable small-scale vessels are commonly used in cell culture studies in academia as well as early stages of bioprocess development. These types of research are crucial for our understanding about cells and bioprocesses as they provide important information regarding different parameters affecting cells. Dissolved carbon dioxide (DCO2) is one main parameter affecting cell metabolism. It is also an indicator of cell culture well-being. Despite CO2 being a critical process parameter, there is a lack of appropriate monitoring system for CO2 in small-scale vessels. Here, we present a membrane-based noninvasive method for measuring DCO2 in cell culture medium. The idea was achieved by modifying a T-flask and replacing a small area of it with CO2 permeable silicone membrane. In the proposed method, the concentration of CO2 dissolved in the cell culture medium is determined by measuring the initial diffusion rate of CO2 through a silicone membrane attached to the bottom wall of the T-flask. The measurement method was validated previously, and the efficacy of the noninvasive method was evaluated by growing E.coli, Pichia pastoris, and CHO cells in the proposed prototype. The results obtained from this method were verified with other quantitative data obtained from the process such as optical density (OD), cell density, dissolved oxygen (DO) and pH. The results show that the proposed membrane-based method is an effective way for completely noninvasive monitoring of DCO2 in small-scale cell culture processes. Additional diffusing species such as oxygen could also be measured using the same approach.

Aqueous dispersions of oxygen nanobubbles for potential application in inhalation therapy

Inhalation is a non-invasive method of local drug delivery to the respiratory system. This study analyzed the potential use of aqueous dispersion of oxygen nanobubbles (ADON) as a drug carrier with the additional function of oxygen supplementation to diseased lungs. The suitability of the membrane-based method of ADON preparation and, next, the stability of ADON properties during storage and after aerosolization in nebulizers of various designs (jet, ultrasonic, and two vibrating mesh devices) was investigated. The increased oxygen content in the aerosol generated in two mesh nebulizers suggests that the proposed concept may be helpful in the oxygen supplementation during drug delivery by aerosol inhalation without using an additional oxygen source. This application can increase the overall effectiveness of lung disease treatment and pulmonary rehabilitation.

Consistency of Mycobacterium tuberculosis Complex Spoligotyping between the Membrane-Based Method and In Silico Approach.

ABSTRACTTo tackle the spread of tuberculosis (TB), epidemiological studies are undertaken worldwide to investigate TB transmission chains. Clustered regulatory interspaced short palindromic repeats (CRISPR) locus diversity, also called spoligotyping, is a widely used genotyping assay for the characterization of Mycobacterium tuberculosis complex (MTBC). We compared herein the spoligotyping of MTBC clinical isolates using a membrane-based method (following an initial PCR step) and whole-genome sequencing (WGS)-based method (i.e., in silico spoligotyping). All MTBC strains isolated at the Lyon University Hospital, France, between November 2016 and December 2020 were included (n = 597). Spoligotyping profiles were also used for species identification among the MTBC. Outputs of both methods were analyzed, and discrepant results were investigated thanks to CRISPRbuilder-TB. The overall agreement was 85.7%. Spacer discrepancies observed between the methods were due to the insertion of IS6110 within the direct repeat (DR) sequence upstream or downstream of spacers, mutated DR sequences, or truncated spacers. Discrepancies did not impact species identification. Although spoligotyping-based species identification was inconclusive for 29 isolates, SNP-based phylogeny conducted after WGS allowed the identification of 23 M. tuberculosis (Mtb), 2 M. canettii, and 4 mixed MTBC infections. WGS yielded very few discrepancies compared to membrane-based spoligotyping. Overall agreement was significantly improved (92.4%) by the CRISPR locus reconstruction using CRISPRbuilder-TB for the MTBC isolates with the shared international type 53 in silico spoligotyping. A smooth transition from the membrane-based to the in silico-based genotyping of M. tuberculosis isolates is, therefore, possible for TB diagnosis and epidemiologic survey.IMPORTANCE Whole-genome sequencing (WGS) has profoundly transformed the perspectives of tuberculosis (TB) diagnosis, providing a better discriminatory power to determine relatedness between Mycobacterium tuberculosis complex (MTBC) isolates. Previous genotyping approaches, such as spoligotyping consisting of an initial PCR step followed by reverse dot hybridization, are currently being replaced by WGS. Several pipelines have been developed to extract a spoligotype from WGS data (in silico spoligotyping) allowing for the continuity of MTBC molecular surveys before and after WGS implementation. The present study found very good overall agreement between hybridization to membrane-based spoligotyping and in silico spoligotyping, indicating the possibility of a smooth transition from the traditional to the in silico-based genotyping of MTBC isolates for TB diagnosis and epidemiological survey.

Life cycle and economic assessments of petroleum refineries wastewater recycling using membrane, resin and on site disinfection (UF-IXMB-MOX) processes

The use of treated effluent as a sustainable, reliable, and accessible source of water supply is a critical factor influencing water use in industrial sectors like petroleum refineries. The purpose of this study is to document the life cycle and economic assessment of an integrated ultrafiltration, ion exchange, and multioxidant (UF-IXMB-MOX) treatment system in the recycling of refinery effluent. The effluent was used to supply makeup water in cooling towers at the Kermanshah oil refinery, Iran from April to December 2018. For the life cycle analysis, eight environmental indicators, including ozone-depleting potential (ODP), global warming (GW), greenhouse gases (GHG), acidification potential (AP), eutrophication potential (EP), health effects (HE), environmental toxicity potential (ETP) and photochemical oxidation potential (POCP) were considered for four groups influencing the selection of a treatment method, including electricity consumption (EC), raw materials, condensed effluent (concentrate) and construction. Results of the economic analysis show that the initial investment for the launch of this treatment system was estimated at $255,750. Considering the fixed and variable annual costs, the cost of regenerating treated effluent was estimated at $0.24/m3 of effluent, with the cost of chemicals contributing the most to annual costs. This scenario, with consumption of 0.08kWh/m3, had the lowest energy consumption compared to other similar membrane-based methods. The electricity consumption in the formation of GHGs, GW, POCP, and health effects, and the role of condensed effluent produced in creating ETP in aquatic and terrestrial environments, had the highest environmental impact among the eight environmental indicators. Overall, results suggest that focusing on renewable energy and the use of chemicals with minimal economic and environmental impact can increase the efficiency of this process.

Electrospun nanofibrous membranes as promising materials for developing high-performance desalination technologies

Rising population, together with rapid industrial development, are making freshwater shortage an ever-increasing crisis globally. In addition to the conventional strategy such as water reuse, desalination has proven to be an effective method to meet this requirement, especially membrane-based desalination technology. Besides the conventional reverse osmosis (RO) and nanofiltration (NF) desalination, other membrane-based methods such as membrane distillation (MD) and forward osmosis (FO) have also been exploited as promising alternatives. For all the membrane-based desalination, performance of the membrane is the key issue. However, the currently used membranes for the main desalination technologies are all faced with some challenges, e.g., low permeation for RO, low selectivity for NF, wetting for MD, and internal concentrative polarization for FO. Thus, researchers are all pursuing more advanced membranes to meet these challenges. Particularly, developing novel membranes is a promising alternative. Electrospun nanofibrous membranes (ENMs) provide an alternative for various membrane-based desalination thanks to their versatility in tuning membrane morphology, structure, composition, fiber diameter, pore size and pore size distribution, and fiber/membrane functionalization. In this review paper, we discussed the application of ENMs in typical membrane desalination process presented by RO, NF, MD, and FO. We emphasize on the usage of superiorities of ENMs in tackling the problems of the currently used membranes such as low membrane permeability, membrane wetting, and internal concentrative polarization. We also proposed the future directions of ENMs development in developing more advanced membranes for desalination.

Extraction of the Bacterial Extracellular Polysaccharide FucoPol by Membrane-Based Methods: Efficiency and Impact on Biopolymer Properties.

In this study, membrane-based methods were evaluated for the recovery of FucoPol, the fucose-rich exopolysaccharide (EPS) secreted by the bacterium Enterobacter A47, aiming at reducing the total water consumption and extraction time, while keeping a high product recovery, thus making the downstream procedure more sustainable and cost-effective. The optimized method involved ultrafiltration of the cell-free supernatant using a 30 kDa molecular weight cut-off (MWCO) membrane that allowed for a 37% reduction of the total water consumption and a 55% reduction of the extraction time, compared to the previously used method (diafiltration-ultrafiltration with a 100 kDa MWCO membrane). This change in the downstream procedure improved the product’s recovery (around 10% increase) and its purity, evidenced by the lower protein (8.2 wt%) and inorganic salts (4.0 wt%) contents of the samples (compared to 9.3 and 8.6 wt%, respectively, for the previously used method), without impacting FucoPol’s sugar and acyl groups composition, molecular mass distribution or thermal degradation profile. The biopolymer’s emulsion-forming and stabilizing capacity was also not affected (emulsification activity (EA) with olive oil, at a 2:3 ratio, of 98 ± 0% for all samples), while the rheological properties were improved (the zero-shear viscosity increased from 8.89 ± 0.62 Pa·s to 17.40 ± 0.04 Pa·s), which can be assigned to the higher purity degree of the extracted samples. These findings demonstrate a significant improvement in the downstream procedure raising FucoPol’s recovery, while reducing water consumption and operation time, key criteria in terms of process economic and environmental sustainability. Moreover, those changes improved the biopolymer’s rheological properties, known to significantly impact FucoPol’s utilization in cosmetic, pharmaceutical or food products.

Treatment and Disposal Methods of Concentrate Stream of Seawater Reverse Osmosis- A Review

The exponentially multiplying population of the world demands increasing freshwater resources. Thelimited resources comprising less than 3% of the earth’s water resources are getting polluted at an alarming rate. To deal with this situation, seawater reverse osmosis is being carried out at large scales across the globe. The concentrate generated in return is two times more concentrated in terms of total dissolved solids when compared to the feed. The adverse effects of the concentrate stream on the marine ecosystem and further pollution of water cause an immediate need to treat the concentrate. In this review, the harm caused by the direct discharge of concentrate stream has been discussed and therefore volume minimization using treatment methods has been addressed. The treatment methods are mainly classified into four types; membrane-based, thermal-based, electricity-based, and chemical-based methods. Integrated methods, which have been mainly tested on a pilot scale for zero liquid discharge, have also been discussed. The treatment methods that are probable for seawater concentrate treatment falling under the above categories for other concentrate sources have also been attended to. Finally, the disposal methods employed for the discharge of the leftover concentrate have been addressed. Thermal methods are well established but require a lot of energy compared to other methods whereas chemical methods can be economic due to the profit obtained from recovered chemicals, but they are mostly employed for pretreatment. Electricity-based and membrane-based methods are emerging technologies. It was also found that seawater reverse osmosis concentrate is usually discharged directly and therefore integrated methods based on zero liquid discharge are to be implemented. To compensate for the intensive research required for zero liquid discharge to become a reality, innovative and environmentally-friendly disposal methods are available to cut the resultant footprint.