Membrane Processes Research Articles

Non-destructive monitoring and prediction of fouling by organic matters and residual anionic coagulant during membrane process

Physical fouling characteristics on silicon carbide (SiC) membranes induced by various organic matter compounds vary depending on the presence of calcium ions (Ca2+). Both destructive techniques (morphological surface analysis) and non-destructive techniques (fouling properties monitoring) were used to determine the fouling mechanisms and behavior during the membrane filtration systems. Destructive analysis and a modified Hermia model were employed to assess the fouling mechanisms. Fouling behavior was also analyzed through non-destructive monitoring techniques including optical coherence tomography (OCT) and three-dimensional laser scanning confocal microscopy (3D-LSM). At concentrations of 10, 30, and 100 mg/L without Ca2+, the flux decreased by 57–95% for humic acid (HA) and anionic polyacrylamide (APAM). APAM exhibited a notable removal rate of up to 56% without Ca2+. At concentration of 10, 30, and 100 mg/L in the absence of Ca2+, the flux decreased by 6–8% for sodium alginate (SA). However, the addition of Ca2+ led to a reduction in the flux for SA by up to 91% and resulted in a removal rate of 40%. Furthermore, addition of Ca2+ led to an alteration of the fouling characteristics of HA and SA. In the case of HA, higher concentrations resulted in elevated thickness and roughness with correlation coefficients of 0.991 and 0.992, respectively. For SA, increased SA concentration led to a thicker (correlation coefficient of 0.999) but smoother surfaces (correlation coefficients of 0.502). Monitoring of these physical characteristics of the fouling layer through non-destructive analysis is crucial for effective fouling management, optimization of the system performance and extending the lifespan of the membrane. By continuously assessing the fouling layer thickness and surface roughness, we expect to be able to provide insights on the fouling behavior, identify trends, that can help scientists and engineers to make informed decisions regarding fouling control strategies in future.

Biogas Upgrading Using a Single-Membrane System: A Review.

In recent years, the use of biogas as a natural gas substitute has gained great attention. Typically, in addition to methane (CH4), biogas contains carbon dioxide (CO2), as well as small amounts of impurities, e.g., hydrogen sulfide (H2S), nitrogen (N2), oxygen (O2) and volatile organic compounds (VOCs). One of the latest trends in biogas purification is the application of membrane processes. However, literature reports are ambiguous regarding the specific requirement for biogas pretreatment prior to its upgrading using membranes. Therefore, the main aim of the present study was to comprehensively examine and discuss the most recent achievements in the use of single-membrane separation units for biogas upgrading. Performing a literature review allowed to indicate that, in recent years, considerable progress has been made on the use of polymeric membranes for this purpose. For instance, it has been documented that the application of thin-film composite (TFC) membranes with a swollen polyamide (PA) layer ensures the successful upgrading of raw biogas and eliminates the need for its pretreatment. The importance of the performed literature review is the inference drawn that biogas enrichment performed in a single step allows to obtain upgraded biogas that could be employed for household uses. Nevertheless, this solution may not be sufficient for obtaining high-purity gas at high recovery efficiency. Hence, in order to obtain biogas that could be used for applications designed for natural gas, a membrane cascade may be required. Moreover, it has been documented that a significant number of experimental studies have been focused on the upgrading of synthetic biogas; meanwhile, the data on the raw biogas are very limited. In addition, it has been noted that, although ceramic membranes demonstrate several advantages, experimental studies on their applications in single-membrane systems have been neglected. Summarizing the literature data, it can be concluded that, in order to thoroughly evaluate the presented issue, the long-term experimental studies on the upgrading of raw biogas with the use of polymeric and ceramic membranes in pilot-scale systems are required. The presented literature review has practical implications as it would be beneficial in supporting the development of membrane processes used for biogas upgrading.

Energetic Comparison of Flow-Electrode Capacitive Deionization and Membrane Technology: Assessment on Applicability in Desalination Fields.

Flow-electrode capacitive deionization (FCDI) is a promising technology for sustainable water treatment. However, studies on the process have thus far been limited to lab-scale conditions and select fields of application. Such limitation is induced by several shortcomings, one of which is the absence of a comprehensive process model that accurately predicts the operational performance and the energy consumption of FCDI. In this study, a simulation model is newly proposed with initial validation based on experimental data and is then utilized to elucidate the performance and the specific energy consumption (SEC) of FCDI under multiple source water conditions ranging from near-groundwater to high salinity brine. Further, simulated pilot-scale FCDI system was compared with actual brackish water reverse osmosis (BWRO) and seawater reverse osmosis (SWRO) plant data with regard to SEC to determine the feasibility of FCDI as an alternative to the conventional membrane processes. Analysis showed that FCDI is competent for operation against brackish water solutions under all possible operational conditions with respect to the BWRO. Moreover, its distinction can be extended to the SWRO for seawater conditions through optimization of its total effective membrane area via scale-up. Accordingly, future directions for the advancement of FCDI was suggested to ultimately prompt the commercialization of the FCDI process.

Autophagosome biogenesis and organelle homeostasis in plant cells.

Autophagy is one of the major highly inducible degradation processes in response to plant developmental and environmental signals. In response to different stimuli, cellular materials, including proteins and organelles, can be sequestered into a double membrane autophagosome structure either selectively or nonselectively. The formation of an autophagosome as well as its delivery into the vacuole involves complex and dynamic membrane processes. The identification and characterization of the conserved autophagy-related (ATG) proteins and their related regulators have greatly advanced our understanding of the molecular mechanism underlying autophagosome biogenesis and function in plant cells. Autophagosome biogenesis is tightly regulated by the coordination of multiple ATG and non-ATG proteins and by selective cargo recruitment. This review updates our current knowledge of autophagosome biogenesis, with special emphasis on the core molecular machinery that drives autophagosome formation and autophagosome-organelle interactions under abiotic stress conditions.

Coupling of nanostraws with diverse physicochemical perforation strategies for intracellular DNA delivery

Effective intracellular DNA transfection is imperative for cell-based therapy and gene therapy. Conventional gene transfection methods, including biochemical carriers, physical electroporation and microinjection, face challenges such as cell type dependency, low efficiency, safety concerns, and technical complexity. Nanoneedle arrays have emerged as a promising avenue for improving cellular nucleic acid delivery through direct penetration of the cell membrane, bypassing endocytosis and endosome escape processes. Nanostraws (NS), characterized by their hollow tubular structure, offer the advantage of flexible solution delivery compared to solid nanoneedles. However, NS struggle to stably self-penetrate the cell membrane, resulting in limited delivery efficiency. Coupling with extra physiochemical perforation strategies is a viable approach to improve their performance. This study systematically compared the efficiency of NS coupled with polyethylenimine (PEI) chemical modification, mechanical force, photothermal effect, and electric field on cell membrane perforation and DNA transfection. The results indicate that coupling NS with PEI modification, mechanical force, photothermal effects provide limited enhancement effects. In contrast, NS-electric field coupling significantly improves intracellular DNA transfection efficiency. This work demonstrates that NS serve as a versatile platform capable of integrating various physicochemical strategies, while electric field coupling stands out as a form worthy of primary consideration for efficient DNA transfection.

Treatment of real textile effluent containing indigo blue dye by hybrid system combining adsorption and membrane processes

The rapid expansion of the textile industry in Tunisia has resulted in ever-increasing discharges of wastewater, making it necessary to set up treatment systems allowing i) its discharge into the environment or ii) to recycle the water in the textile plant. In this study, several unitary operations were tested in order to improve the treated water quality. Thus, the following unit operations were applied: adsorption using Natural Clay (NC) and Powdered Activated Carbon (PAC), ultrafiltration (UF) and nanofiltration (NF) individually or in synergy: UF, nanofiltration, PAC-UF, NC-UF, UF-NF et Adsorption-UF/NF. The experiments were carried out on real textile effluent containing Indigo blue dye. A threshold concentration was observed above which performance no longer increases. NF alone showed better reduction of COD (67%), color (78%), and turbidity (98%) than UF alone (26%, 48%, 95%, respectively). The coupling UF–NF showed a clear improvement in water quality in terms of color (99%) and COD (98%) with an improvement in the NF flux from 67.81 L/h.m2 to 90.62 L/h.m2. No fouling was observed for NF while it is significant during UF. The used of adsorption as pretreatment to filtration leads to an enhancement of the treatment performances with a removal of 99.9%, 99.5% and 79.5% respectively for turbidity, color and COD for NC-UF and a removal of 100%, 99.4% and 79.6% respectively for turbidity, color and COD for PAC-UF. Moreover, the addition of adsorbent controls the fouling and a constant and high flux is quickly attained and remains stable over time. The use of natural clay as adsorbent represents an economically profitable solution since it can be obtained locally and the clay used can be reused in the ceramic industry as an additive for road surfacing without the need for regeneration.

Investigation of the pH-mediated fabrication process of pure and polyethyleneimine-crosslinked graphene oxide membranes for desalination and heavy metal ion separation

Graphene oxide (GO) membranes have been extensively investigated and employed in separating various ions and molecules due to their superior physicochemical properties. However, the inconsistency in their pore structure, difficulty in the precise tuning of their d-spacing, and instability in aqueous solution – especially at extreme pH values – might hinder their separation efficiency. In this research, we systematically investigated the pH-mediated fabrication process of graphene oxide membranes and evaluated the properties of the resulting membranes. Findings from scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses show that a higher fabrication pH results in a thicker GO layer and an enlarged d-spacing due to the deprotonation of the GO's carboxyl groups. Furthermore, pH-assisted crosslinking between polyethyleneimine (PEI) and GO sheets were facilitated and the chemical analysis results suggest that in acidic environments, the dominant reaction involves C–N bond formation at the basal plane, whereas under alkaline conditions, N–CO (amide) bond formation at the edges is more prevalent. This, in return, accordingly shifted the trend in SEM and XRD, where a thinner GP layer and a decreased d-spacing were observed at a higher fabrication pH due to the deprotonation of the incorporated PEI's amine groups. These findings contributed to the nanofiltration (NF) performance of the membranes against different inorganic salts and heavy metal ions. It was discovered that the GPpH11 membrane formed at pH 11 has the highest Pb2+ rejection of >95%, making it a suitable material for heavy metal ions removal.

Process Optimization of an In-Situ Bioleaching Section with Associated Membrane Filtration in a Field Test Laboratory

The winning of critical raw materials from secondary resources, e.g., from abandoned mines, mining residues, electronic waste or low-grade ores, is a potential source with promising outcomes due to innovative and more efficient extraction methods. The research and education mine “Reiche Zeche” at the TU Bergakademie Freiberg, Germany offers a scientific lab in a real application environment for an in-situ bioleaching section from a low-grade sulfide ore vein with on-site associated membrane downstream processing. The evaluation and resumption of previous research activities showed both the feasibility and the potential for further up-scaling. But there was also potential evaluated for improving the effectiveness, especially in terms of individual process elements within the leaching and membrane cycle as well as regarding microbiology. Based on this, further optimization was carried out and effectiveness was evaluated and compared to the prior state. The results regarding the leaching outcome proved that process optimization leads to stable and continuous leaching process operations as well as to improved and more favorable conditions for the microorganisms due to the implementation of a bioreactor and changing the whole leaching operation from a direct into an indirect process. Furthermore, cleaning in place (CIP) resulted in the maintenance of selectivity despite discontinuous membrane process operation.

A Comparative Study on the Removal of Fluorides from Groundwater: Strategies and Technologies

This study conducts a comprehensive comparative analysis of various strategies and technologies employed for the removal of fluorides from groundwater, addressing the increasing concern over elevated fluoride levels in water sources. High fluoride concentrations pose significant health risks, including dental and skeletal fluorosis, necessitating effective and sustainable removal methods. The research evaluates the efficiency, cost-effectiveness, and environmental impact of different fluoride removal techniques, providing valuable insights for water treatment practitioners, policymakers, and communities grappling with fluoride-contaminated groundwater. The study begins by outlining the prevalence of fluoride contamination in groundwater and the associated health risks, establishing the critical need for reliable removal methods. Subsequently, a review of existing literature presents an overview of conventional and emerging technologies utilized for fluoride removal. Conventional methods such as coagulation, precipitation, and adsorption are examined, considering their efficiency, operational ease, and cost implications. The study then delves into advanced technologies like membrane processes, ion exchange, and electrochemical methods, assessing their applicability and effectiveness in diverse groundwater contexts. Environmental sustainability is a key focus throughout the analysis, with a critical examination of the by-products and waste generated by each removal method. The ecological footprint, including energy consumption and material usage, is considered to provide a holistic understanding of the environmental impact associated with fluoride removal technologies. Furthermore, the economic feasibility of each method is evaluated, considering capital and operational costs. Comparative cost analyses offer insights into the affordability and scalability of different removal technologies, aiding decision-makers in selecting suitable methods based on financial constraints. The study concludes with a synthesized overview of the comparative analysis, emphasizing the strengths and limitations of each fluoride removal method. In summary, this comparative study contributes to the broader understanding of fluoride removal technologies, facilitating informed decision-making in addressing groundwater contamination. The findings are anticipated to inform researchers, water treatment professionals, and policymakers, guiding the selection of appropriate and context-specific fluoride removal methods to ensure safe and potable groundwater sources

Treatment of tomato paste wastewater by electrochemical and membrane processes: process optimization and cost calculation.

This study investigated the treatment of wastewater from tomato paste (TP) production using electrocoagulation (EC) and electrooxidation (EO). The effectiveness of water recovery from the pretreated water was then investigated using the membrane process. For this purpose, the effects of independent control variables, including electrode type (aluminum, iron, graphite, and stainless steel), current density (25-75 A/m2), and electrolysis time (15-120 min) on chemical oxygen demand (COD) and color removal were investigated. The results showed that 81.0% of COD and 100% of the color removal were achieved by EC at a current density of 75 A/m2, a pH of 6.84 and a reaction time of 120 min aluminum electrodes. In comparison, EO with graphite electrodes achieved 55.6% of COD and 100% of the color removal under similar conditions. The operating cost was calculated to be in the range of $0.56-30.62/m3. Overall, the results indicate that EO with graphite electrodes is a promising pretreatment process for the removal of various organics. In the membrane process, NP030, NP010, and NF90 membranes were used at a volume of 250 mL and 5 bar. A significant COD removal rate of 94% was achieved with the membrane. The combination of EC and the membrane process demonstrated the feasibility of water recovery from TP wastewater.

Investigation of phenolic compounds recovery from brewery wastewater with coupled membrane and adsorption process

Recovery of phenolic compounds from food-processing by-products represents an interest for various industrial sectors. The potential of a coupled ultrafiltration and adsorption or ion exchange resin process was analyzed to recover phenolic compounds from a brewery liquid residue. Ultrafiltration yielded a 95% removal of turbidity-causing compounds without significant modification of the chemical composition of brewery by-products. After a pH optimization step, ten different macroporous resins, including MN202, SP700, HP2MGL, LXA8302, LWT510, XAD16N, FPX66, WA20, WA30 and SCAV4, were screened for phenolic compounds sorption. Resins were selected through a multi-step batch test procedure according to their performance in phenolic compounds adsorption capacity, phenolic compounds selectivity compared to carbohydrates and price. The strong base resin SCAV4 with OH- counter ion showed the highest adsorption capacity, 35.4 ± 0.8 mg·gdryresin−1, with selective sorption of phenolic compounds. Higher temperatures of 48 °C improved the adsorption and desorption performances of LXA8302 and SCAV4 resins, compared to 25 °C. Up to 70% of phenolic compounds were desorbed from adsorption resin with adequate solvent.

Controlled architecture of multi-defense anti-fouling forward osmosis membrane for efficient shale gas wastewater treatment

Forward osmosis (FO) membrane process facilitates effective treatment of shale gas wastewater (SGW) due to its tolerance to high salinity and exceptional separation performance. However, serious membrane fouling remains a challenge regarding the complexity of realistic SGW. To address the fouling issues, controlled block copolymer architecture was constructed on the FO membrane surface to achieve combined effect of oil-resistance, self-regenerating, and fouling mitigation. In the modification process, zwitterionic polymer with strong hydrophilicity and fluoropolymers with low surface energy were successively grafted to the membrane active layer by atom transfer radical polymerization. The outermost fluoropolymer layer with low surface energy imparts the membrane with anti-oil and self-regenerating capabilities. Meanwhile, the strong hydration effect of the zwitterionic polymer ensures that nonspecific foulants breaking through the outermost defense are kept away from the membrane surface. According to the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the modified FO membrane exhibited a significantly higher total interaction energy (ΔGTOT) compared to the pristine membrane when exposed to various types of model foulants (bovine serum albumin, humic acid, sodium alginate, mineral oil). Furthermore, the advantage of having multiple defense mechanisms was further substantiated through dynamic filtration tests with realistic SGW. In comparison to the pristine TFC membrane, the modified membrane not only experienced a much smaller decrease in water flux (reduced by 52%) during fouling but also an exceptional flux recovery after cleaning (∼97%). These findings underscore that the modified FO membranes greatly mitigated membrane fouling associated with SGW through the synergistic interplay between a zwitterionic polymer and a low surface energy material, highlighting its promising potential in SGW treatment via membrane technology.

Dextran sulfate bulk and surface-modified microfiltration membrane for simultaneous blood plasma harvesting and low-density lipoprotein removal during plasmapheresis

Plasmapheresis is currently used for the harvesting of blood plasma in medical labs and plasma donation centers. This is a fast, single-step membrane process for both collection of blood plasma and simultaneous blood cell isolation. This paper presents the development of a novel membrane that can be used to simultaneously harvest blood plasma and isolate low-density lipoprotein (LDL), known as bad cholesterol, from the blood. To achieve this goal, dual surface and bulk modification by dextran sulfate (DS) was performed on a polyethersulfone (PES) membrane containing single wall carbon nanotubes (SWCNT). DS is an anionic ligand that repels negatively charged substances like red blood cells (RBCs) and adsorbs positively charged substances like Apo B100; the apoprotein of LDL. Scanning Electron Microscope (SEM), Energy Dispersive X-Ray (EDX), and Fourier Transform Infrared (FTIR) spectroscopy analyses provided evidence of the grafting of DS on single wall carbon nanotubes (DS-SWCNT). Surface studies including water contact angle, zeta potential analysis, surface morphology, Attenuated Total Reflectance-FTIR (ATR-FTIR), and EDX, confirmed the presence of DS on the PES membrane surface. The SEM cross-section results showed the formation of a two-zone morphology with an open structure on the upside and a dense structure on the downside that provide optimal conditions for efficient separation of blood cells. The complete blood count (CBC) and biochemistry analyses revealed dual bulk and surface-modified membrane, and a specific sample (DM2) showed the best performance for blood cells and LDL separation. The maximum separation of blood cells was 87% RBC, 98% white blood cells (WBCs), and 83% platelets (PLTs). Moreover, DM2 exhibited a sieving ratio for LDL of 0.33. Blood compatibility analyses confirmed that DM2 and other related samples had low hemolysis and prolonged coagulation times.

Mining phase separation-related diagnostic biomarkers for endometriosis through WGCNA and multiple machine learning techniques: a retrospective and nomogram study.

The objective of this study was to investigate the role of phase separation-related genes in the development of endometriosis (EMs) and to identify potential characteristic genes associated with the condition. We used GEO database data, including 74 non-endometriosis and 74 varying-degree EMs patients. Our approach involved identifying significant gene modules, exploring gene intersections, identifying core genes, and screening for potential EMs biomarkers using weighted gene co-expression network analysis (WGCNA) and various machine learning approaches. We also performed gene set enrichment analysis (GSEA) to understand relevant pathways. This comprehensive approach helps investigate EMs genetics and potential biomarkers. Nine genes were identified at the intersection, suggesting their involvement in EMs. GSEA linked DEGs to pathways like complement and coagulation cascades, DNA replication, chemokines, apical plasma membrane processes, and diseases such as Hepatitis B, Human T-cell leukemia virus 1 infection, and COVID-19. Five feature genes (FOS, CFD, CCNA1, CA4, CST1) were selected by machine learning for an effective EMs diagnostic nomogram. GSEA indicated their roles in mismatch repair, cell cycle regulation, complement and coagulation cascades, and IL-17 inflammation. Notable differences in immune cell proportions (CD4 T cells, CD8 T cells, DCs, macrophages) were observed between normal and disease groups, suggesting immune involvement. This study suggests the potential involvement of phase separation-related genes in the pathogenesis of endometriosis (EMs) and identifies promising biomarkers for diagnosis. These findings have implications for further research and the development of new therapeutic strategies for EMs.

Template-assisted fabrication of polyether ether ketone hollow fiber membrane for highly efficient separation of binary dye mixtures

Poly(ether ether ketone) (PEEK) is among the most reliable membrane materials in membrane-based separation processes due to its excellent properties especially under harsh environment. Successfully implementing the controllable construction of the pore structure into the fabrication process of PEEK hollow fiber membranes (HFMs) can make a significant contribution to addressing the issue of membrane selectivity and permeability. Herein, we developed a flexible route for manufacturing PEEK HFMs by melt-spinning technology combined with the template-assisted crystallization process. This route effectively reduced the amount of organic solvent in the membrane preparation process, and the crystallization induced strategy remarkably improved the connectivity of membrane pore structure and fixed pore structure of PEEK HFMs. Furthermore, we conducted a comprehensive investigation into the separation mechanism and performance stability of the prepared membranes in binary dye mixtures. The results unveiled that the suitable pore structure of the PEEK HFMs that maintained a high salt permeability with a high dye retention, synergized with strong negative charge contributed to excellent performance in dye/salts or dye/dye binary mixtures separations. A long-term stability of PEEK HFMs for treatment of the simulated textile wastewater with rejection coefficient of above 99% to dyes like congo red (CR) and a low NaCl rejection (<10%) indicated that PEEK HFMs have a bright prospect in dye/salt separation for water purification and resource reclamation.

Membrane processes used to treat scrubber gas desulfuration washwater.

Since 2020, hybrid exhaust gas cleaning systems have been installed on container ships to be in line with the International Maritime Organisation regulations. This technology allows the removal of gaseous sulphur oxide compound before atmospheric rejection of exhaust gas with a concentration lower than 0.1% sulphur equivalent. To be also compliant with water discharge criteria, membrane processes used as a water treatment system have been complementary installed onboard maritime vessels. Objectives of our research are to demonstrate the membrane efficiency and performances for this field of application and their reliability for reaching future regulations. Half industrial scale experiments are first carried out in controlled areas. Results allow optimum parameter definition for a sustainable long-term operation as a permeate flux of 60 L h-1 m-2 and a backwash frequency of 40 min. Experiments are scaled up to onboarded units, and previous settings have been validated. The fleet autonomy for a longer period of closed-loop operation is highlighted. Consequently, the fleet is well prepared and able to overcome new regulation for the future sulphur emission area defined for the Mediterranean Sea in 2025. In addition, the usage of membrane processes allows the reduction of pollutants as suspended solid and heavy metal rejection inside the natural environment with a respective retention higher than 100 and 95%.

A dialysis membrane process for the in vitro simulation of bile acids absorption in the small intestine

Accounting for the complexity of the human digestion process remains a challenge for in vitro digestion (IVD) model systems, with the absorption of bile acids (BAs) being among the greatest challenges. This study aimed to develop an online dialysis membrane process utilizing hollow fiber membranes for mimicking the intestinal absorption of BAs. Different flow rates were examined, to determine the most optimal for the highest reduction of BAs. The obtained knowledge facilitated the identification of the governing principles of BA absorption, i.e., (i) the catalytic activity of pancreatin in releasing BAs from the food matrix, (ii) the mass transfer of BAs through the membrane, due to diffusion and convective transport (iii) the water removal from digesta. This study offers an open-source, simple and reproducible dialysis system able to simulate BAs' absorption during the IVD of an emulsified food model system in a realistic timeframe, unlike other IVD systems implementing dialysis.

Improving the quality of liquid smoke by filtration using membranes

Liquid smoke (LS) is getting more attention in many applications, especially food preservation. However, there is still a big problem with the purity of LS. The objective of this study is to improve the quality of LS using membrane filtration. The filtrations were conducted using ultrafiltration or nanofiltration membrane at various pressures. The quality of LS before and after filtration was compared based on their appearance. During the filtration process, LS changed from a dark yellow fluid with a pungent odor to a pale colorless substance with a less smokey odor and a slightly sweet aroma. The color and fragrance parameters of LS before and after filtration using UF membranes were not significantly different. NF membrane filtering had the opposite effect on the appearance of LS. Chemical composition of volatile fraction was studied by GC/MS. Phenols were the predominant aromatic chemicals found in all samples, with LS containing up to 80.8%, 17.53% in treated LS by UF membrane (2 bars), and 48.31% in NF membrane (5 bars). The results proved that the membrane processing can eliminates potentially toxic compounds while still imparting the desired flavors and pleasent aromas of LS.

WITHDRAWN: Concentrate Management of Spent Geothermal Water Treated with Two- Step Membrane Processes for Agricultural Irrigation

This study examines a two-step membrane treatment to improve water quality by targeting electrical conductivity in reverse osmosis (RO) concentrate from spent geothermal water. The process involves RO treatment followed by electrodialysis reversal (EDR). Water samples were collected during different seasons to assess quality under varying conditions.Following the initial treatment by XLE-RO membrane test system, the large-pilot membrane (LPM-RO) concentrate achieved salt rejection of 98.6%, while the mini-pilot membrane (MPM-RO) concentrate achieved salt rejection of 95.6%. Conductivity values were 48.6µS/cm for LPM-RO and 226µS/cm for MPM-RO concentrate. Further passing the product water obtained from XLE-RO membrane through the EDR system improved overall product water quality. Treated LPM-RO product water had conductivities of 3.71µS/cm (5V) and 2.36µS/cm (10V). For MPM-RO product water, conductivities were 11.98µS/cm (5V) and 2.64µS/cm (10V). In this study, an additional experiment investigated the EDR treatment of RO concentrate without undergoing initial RO pretreatment. After the experiment, although the salt rejection reached 97.65%, it was observed that the product water quality at the end of the 90-minute treatment was 74.6µS/cm with lower quality as compared to when the RO concentrate underwent initial RO pre-treatment. Hence, the combination of RO-EDR can be successfully utilized to treat geothermal water concentrate for better quality which could be utilized in irrigation. This two-step membrane treatment shows potential for higher-quality water reclamation for various processes.

A novel process for rutin recovery from model solutions using nanofiltration: Experimental study, mathematical modeling, and scale‐up design

AbstractPressure‐driven membrane processes represent a credible method for the separation and concentration of natural polyphenols. The separation characteristics and their productivity depend on several factors such as molecular weight cut‐off, operating conditions, and test cell parameters. In this study, a compact polyamide HFT‐NF150 nanofiltration membrane has been tested to separate different model solutions of rutin, and the effects of operating conditions like trans‐membrane pressure, feed concentration, and feed flow rates were analyzed. All the findings of the experiment revealed that the maximum permeate flux of 3.04 × 10−5 m3/m2 s and 98.5% rejection were obtained at a high feed flow rate of 36 L/h and a high pressure of 6 × 105 Pa. Also, the Spiegler–Kedem model is used to report the mass transport phenomenon across the membrane. The unconstrained minimization technique based on the simplex search method was applied for the estimation of the unknown parameters. The theoretical and experimental values for permeate characteristics were then compared for each experimental data point for the model validation. Later, a mathematical model was used to check the scale‐up viability of the process to the commercial limit.Practical applicationsIn the past few years, naturally occurring bioactive compounds have revolutionized the whole scientific community for their exploration. Rutin is one such phenolic compound that is present in significant amounts in buckwheat and has a wide range of applications in the food and pharmaceutical industries. In this work, an energy‐efficient and cleaner method of nanofiltration is applied to concentrate the rutin from the model plant extract. Experiments were performed on a polyamide nanofiltration membrane with a molecular weight cut‐off of 150 Da at different operating conditions. Experimental results were fitted in a three‐parameter Spiegler–Kedem model to determine the transport parameters of the membrane for rutin. The values of transport parameters were also successfully validated using the experimental results. Experimental results and model predictions were then used to analyze the effects of different operating parameters. A scale‐up setup has been designed and simulated to check the feasibility of the process at the commercial level.