Search Results (73)

Microplastics represent a pressing global environmental concern due to their persistence, widespread occurrence, and adverse impacts on aquatic ecosystems and human health. Effective removal of these contaminants from water is essential to safeguard biodiversity and ensure water quality. This work focuses on the pivotal role of membrane-based filtration technologies, including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, membrane bioreactors, and dynamic membranes, in capturing and eliminating microplastics. The performance of these systems depends on key membrane characteristics such as pore size, material composition, hydrophilicity, mechanical strength, and module design, which govern retention efficiency, fouling resistance, and operational stability. Membrane filtration offers a highly effective, scalable, and sustainable approach to microplastic removal, outperforming conventional treatment methods by selectively targeting a wide range of particle sizes and morphologies. By highlighting the critical contribution of membranes and filtration processes, this study underscores their potential in mitigating microplastic pollution and advancing sustainable water treatment practices. Full article

The integration of Reverse Osmosis (RO) desalination with Renewable Energy (RE) sources offers a sustainable approach to freshwater production, particularly in remote and off-grid regions. However, the variable and intermittent output of RE power can cause operational instability that affects membrane performance and system reliability. This study experimentally evaluated a flat sheet seawater RO membrane under variable conditions emulating a Photovoltaic (PV)-powered system over three days. Three scenarios were examined: (i) steady full-load operation representing PV with battery storage, (ii) variable operation representing sunny-day PV output, and (iii) highly variable operation representing cloudy-day PV output. A Variable Frequency Drive (VFD) regulated by an Arduino microcontroller adjusted high-pressure pump operation in real time to replicate power fluctuations without energy storage. Each scenario operated for eight hours per day and was tested with and without end-of-day rinsing. Under the highly variable cloudy-day scenario without rinsing, water permeability decreased by 37%, salt rejection decreased by 18%, and membrane resistance increased by 37%, indicating compaction and fouling effects. Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) confirmed structural changes in membranes exposed to fluctuating conditions. These results highlight the need for improved operational strategies to protect membrane longevity in RE-powered desalination systems. Full article

Seawater and brackish water desalination using membranes is anticipated to offer a simple and effective solution to the global water shortage, and polysilsesquioxane (PSQ) is expected to be the base material for robust reverse osmosis (RO) membranes for water desalination. Hydroxyethylurea-containing PSQ-based RO membranes for water desalination have recently been developed via a sol–gel process. Although these membranes showed high performance, achieving a water permeability of 1.86 × 10⁻¹² m³ m⁻²s⁻¹Pa⁻¹ and an NaCl rejection of 95.9%, the membranes showed limited chlorine resistance and processibility and moderate heat resistance. In this study, three new urea-containing monomers were designed and prepared for RO membrane preparation. The copolymerization of these urea-containing monomer with bis(triethoxysilylpropyl)amine resulted in performance comparable to that of hydroxyethylurea-containing PSQ membranes. The present urea-containing PSQ membranes exhibited enhanced chlorine resistance, with only 1–3% decreases in NaCl rejection, even after 10,000 ppm h exposure to chlorine, together with 3–19% increases in water permeability. Additionally, the presently prepared urea-containing PSQ membranes exhibited improved processability. This study provides a new molecular design for robust and high-performance RO membranes that can be prepared through a simple sol–gel process. Full article

Groundwater management in volcanic islands represents a complex challenge due to the scarcity of surface resources, the strong heterogeneity of volcanic terrains, and the constant threat of marine intrusion. In Tenerife (Canary Islands, Spain), current regulations establish that only saline or brackish waters are permitted for exploitation, to be subsequently desalinated through reverse osmosis for urban and touristic supply. In this context, it is essential to develop geophysical methodologies capable of accurately characterizing subsurface salinity and optimizing the location of new boreholes. The present study applies Electrical Resistivity Tomography (ERT) profiles in the Los Cristianos area (Arona, Tenerife), later integrated into a three-dimensional model using Oasis Montaj software Version 2025.1. The results allow for the differentiation of four geoelectrical domains. The 3D modeling enabled a detailed characterization of the conductive domain, delineating the geometry of the marine intrusion. The findings confirm that the combination of ERT and 3D modeling constitutes an effective, replicable, and economically efficient methodology for precisely locating saline horizons and selecting the most suitable drilling sites, thereby providing an objective basis for the sustainable management of water resources in volcanic islands. Full article

The implementation of wastewater management strategies and wastewater treatment techniques, such as reverse osmosis (RO), has been increasing to promote environmental sustainability and reduce freshwater consumption. Municipal secondary effluent is a promising source for reuse and reducing the strain on freshwater consumption. Still, its diverse foulant composition promotes the fouling of polyamide RO membranes, leading to performance decline. In this study, 3-allyl-5,5-dimethylhydantoin (ADMH) was grafted onto thin-film composite RO membranes at varying concentrations via graft polymerization. The membranes were tested against foulant solutions of E. coli and S. aureus, as well as organic and inorganic foulant solutions mimicking the fouling activity of municipal wastewater secondary effluent. Biofouling tests showed improved mortality ratios—58.9% against E. coli and 37.4% against S. aureus—along with fouling deposition rates of 3.7–8.9% and flux recovery ratios of 69.2–96.9%. Although surface hydrophilicity increased with ADMH concentration, fouling resistance was optimal at a moderate concentration. Resistance to organic and inorganic foulants did not show similar improvement, highlighting the importance of the foulant type in determining overall membrane performance. Full article

This study evaluated the effectiveness of individual clean-in-place (CIP) steps in removing biofilms from reverse osmosis (RO) membranes under dynamic flow conditions using the Centers for Disease Control (CDC) biofilm reactor. Biofilms were developed in the laboratory under continuous flow, using mixed-species bacterial isolates obtained from 10-month-old RO membrane biofilms from a commercial facility. Individual CIP chemicals, representative of those used in commercial protocols, were tested against 24 h-old biofilms. Additionally, a complete six-step sequential CIP process was conducted under dynamic conditions, consisting of treatments with alkali, surfactant, acid, enzyme, a secondary surfactant, and sanitizer. All experiments were performed in quadruplicate, and data were subjected to statistical analysis. Among individual treatments, the acid step was the most effective, significantly outperforming the other CIP cleaning steps by reducing bacterial counts from 5.62 to 4.10 log units, a 96.98% reduction. The full six-step CIP protocol reduced counts to 2.24 log units, indicating the persistence of resistant cells. The presence of viable cells post-treatment highlights the limited efficacy of the tested CIP chemicals in fully eradicating mature biofilms. Additionally, skipping any step in the membrane cleaning can significantly compromise the efficiency and performance during production. These findings suggest that biofilms grown in vitro under dynamic conditions using the CDC reactor exhibit a more robust assessment of the CIP treatments in accomplishing the biofilm control. This study highlights the need for optimized, scientifically validated CIP protocols targeting biofilms to improve cleaning efficacy and food safety. Full article

The consistent quality control of ultrapure water (UPW) in semiconductor manufacturing depends on removing trace organonitrogen compounds such as urea. Due to its high solubility, chemical stability, and neutral polarity, urea is inadequately removed by conventional processes. Even at low concentrations, it elevates total organic carbon (TOC) and reduces electrical resistivity. The use of reclaimed water as a sustainable feed stream amplifies this challenge because its nitrogen content is variable and persistent. Conventional methods such as reverse osmosis, ultraviolet oxidation, and ion exchange remain limited in treating urea due to its uncharged, low-molecular-weight nature. This review examines the performance and limitations of these processes and explores electrochemical oxidation (EO) as an alternative. Advances in EO are analyzed with attention to degradation pathways, electrode design, reaction selectivity, and operational parameters. Integrated systems combining EO with membrane filtration, adsorption, or chemical oxidation are also reviewed. Although EO shows promise for selectively degrading urea, its application in UPW production is still in its early stages. Challenges such as low conductivity, byproduct formation, and energy efficiency must be addressed. The paper first discusses urea in reclaimed water and associated removal challenges, then examines both conventional and emerging treatment technologies. Subsequent sections delve into the mechanisms and optimization of EO, including electrode materials and operational parameters. The review concludes with a summary of main findings and a discussion of future research directions, aiming to provide a comprehensive foundation for validating EO as a viable technology for producing UPW from reclaimed water. Full article

This work aims to characterize flow-accelerated corrosion of carbon steel A36 coupons exposed to simulated treated reverse-osmosis seawater under ambient conditions and a Reynolds number range of 6000 to 25,000 using a standard corrosion testing method. The flow behavior in the corrosion compartment and the turbulent parameters were determined by computational fluid dynamics simulation. Using selected flow parameters, complemented with experimental corrosion rate measurements, the oxygen mass transfer coefficients (m_c) and the rate constant for the cathodic reaction (k_c) at the coupon surface were determined. As expected, m_c depends only on the fluid conditions, while k_c is highly influenced by interface resistance, leading to significantly different runs with and without a corrosion inhibitor. The dissimilar fluid flow distribution on intrados and extrados generates irregular corrosion patterns, depending on the angular position of the coupon inside the corrosion compartment. Morphological studies using scanning electron microscopy and atomic force microscopy support simulation results. Full article

Reverse osmosis (RO) desalination technology offers a promising solution for mitigating water scarcity. However, one of the major challenges faced by RO membranes is biofouling, which significantly increases the desalination costs. Traditional simulation models often overlook environmental variability and do not incorporate the effects of membrane-surface modifications. This paper develops a bacterial growth model for the prediction of seawater desalination performance, applicable to commercial RO membranes, which can be either uncoated or coated with iron nanoparticles (FeNPs or nZVI). FeNPs were selected due to their known antimicrobial properties and potential to mitigate biofilm formation. The native seawater bacterium Bacillus halotolerans MCC1 was used as a model biofouling bacterium. Growth kinetics were determined at different temperatures (from 26 to 50 °C) and pH values (from 4 to 10) to obtain growth parameters. Microbial growth on RO membranes was modeled using the Monod equation. The desalination performance was evaluated in terms of hydraulic resistance and permeate flux under clean and biofouled conditions. The model was validated using desalination data obtained at the laboratory scale. Bacteria grew faster at 42 °C and pH 10. The pH had a more significant effect than temperature on the bacterial growth rate. The FeNP-coated membranes exhibited lower resistance and maintained a higher long-term water flux than the commercial uncoated membrane. This modeling approach is useful for improving the monitoring of feed water parameters and assessing the operational conditions for minimum biofouling of RO membranes. In addition, it introduces a novel integration of environmental parameters and membrane coating effects, offering a predictive tool to support operational decisions for improved RO performance. Full article

Osmotic energy provides an emerging renewable alternative by leveraging the salinity gradient between two solutions. Among these technologies, pressure-retarded osmosis (PRO) has attracted attention; however, its deployment is hindered by obstacles resulting from impurities in feed and draw solutions and lack of suitable membranes. This review explores the integration of membrane-based pretreatments with PRO, highlighting their influence on resolving the technical drawbacks of standalone PRO systems. Membrane-based pretreatments have shown considerable potential to overcome these challenges by improving the quality of water, reducing membrane fouling and enhancing its performance, and ultimately contributing to recovery of energy, resulting in higher power density. Additionally, the use of different nanomaterials has been proposed for membrane modification to optimize PRO performance. Moreover, the study investigates recent advancements in hybrid configurations for harnessing existing infrastructure and to enhance energy efficiency. Offering a comprehensive review on this integrated approach contributes to valuable insights for advancing membrane-based hybrid systems toward commercial viability. Consequently, investment in developing advanced computational modeling and experimental validation, utilization of advanced membrane materials with higher fouling resistance, and optimization of system configurations by using dual-stage and multi-stage designs are required to overcome these limitations. Full article

Forward osmosis (FO) technology, known for its minimal energy requirements, excellent resistance to fouling, and significant commercial potential, shows enormous promise in the development of sustainable technologies, especially with regard to seawater desalination and wastewater. In this study, we improved the performance of the FO membrane in terms of its mechanical strength and hydrophilic properties. Generally, the water flux (J_w) of polyisophenylbenzamide (PMIA) thin-film composite (TFC)-FO membranes is still inadequate for industrial applications. Here, hydrophilic polydopamine (PDA)@ zeolitic imidazolate frameworks-8 (ZIF-8) nanomaterials and their integration into PMIA membranes using the interfacial polymerization (IP) method were investigated. The impact of PDA@ZIF-8 on membrane performance in both pressure-retarded osmosis (PRO) and forward osmosis (FO) modes was analyzed. The durability and fouling resistance of these membranes were evaluated over the long term. When the amount of ZIF-8@PDA incorporated in the membrane reached 0.05 wt% in the aqueous phase in the IP reaction, the J_w values for the PRO mode and FO mode were 12.09 LMH and 11.10 LMH, respectively. The reverse salt flux (J_s)/J_w values for both modes decreased from 0.75 and 0.80 to 0.33 and 0.35, respectively. At the same time, the PRO and FO modes’ properties were stable in a 15 h test. The incorporation of PDA@ZIF-8 facilitated the formation of water channels within the nanoparticle pores. Furthermore, the J_s/J_w ratio decreased significantly, and the FO membranes containing PDA@ZIF-8 exhibited high flux recovery rates and superior resistance to membrane fouling. Therefore, PDA@ZIF-8-modified FO membranes have the potential for use in industrial applications in seawater desalination. Full article

GATA factors are evolutionarily conserved transcription regulators that are implicated in the regulation of physiological changes under abiotic stress. Unfortunately, there are few studies investigating the potential role of GATA genes in potato plants responding to salt and osmotic stresses. The physicochemical properties, chromosomal distribution, gene duplication, evolutionary relationships and classification, conserved motifs, gene structure, interspecific collinearity relationship, and cis-regulatory elements were analyzed. Potato plants were treated with NaCl and PEG to induce salinity and osmotic stress responses. qRT-PCR was carried out to characterize the expression pattern of StGATA family genes in potato plants subjected to salinity and osmotic stress. StGATA12 loss-of-function and gain-of-function plants were established. Morphological phenotypes and growth were indicated. Photosynthetic gas exchange was suggested by the net photosynthetic rate, transpiration rate, and stomatal conductance. Physiological indicators and the corresponding genes were indicated by enzyme activity and mRNA expression of genes encoding CAT, SOD, POD, and P5CS, and contents of H₂O₂, MDA, and proline. The expression patterns of StGATA family genes were altered in response to salinity and osmotic stress. StGATA12 protein is located in the nucleus. StGATA12 is involved in the regulation of potato plant growth in response to salinity and osmotic stress. Overexpression of StGATA12 promoted photosynthesis, transpiration, and stomatal conductance under salinity and osmotic stress. StGATA12 overexpression induced biochemical responses of potato plants to salinity and osmotic stress by regulating the levels of H₂O₂, MDA, and proline and the activity of CAT, SOD, and POD. StGATA12 overexpression induced the up-regulation of StCAT, StSOD, StPOD, and StP5CS against salinity and osmotic stress. StGATA12 could reinforce the ability of potato plants to resist salinity and osmosis-induced damages, which may provide an effective strategy to engineer potato plants for better adaptability to adverse salinity and osmotic conditions. Full article

The fouling of protein on the surface of reverse osmosis (RO) membranes is a surface phenomenon strongly dependent on the physical and chemical characteristics of both the membrane surface and the foulant molecule. Much of the focus on fouling mitigation is on the synthesis of more hydrophilic membrane materials. However, hydrophilicity is only one of several factors affecting foulant attachment. A more systematic and rationalized methodology is needed to screen the membrane materials for the synthesis of fouling-resistant materials, which will ensure the prevention of the accumulation of foulants on the membrane surfaces, avoiding the trial and error methodology used in most membrane synthesis in the literature. If a clear correlation is found between various membrane surface properties, in combination or singly, and the amount of fouling, this will facilitate the establishment of a systematic strategy of screening materials and enhance the selection of membrane materials and therefore will reflect on the efficiency of the membrane process. In this work, eight commercial reverse osmosis membranes were tested for bovine serum albumin (BSA) protein fouling. The work here focused on three surface membrane properties: the surface roughness, the water contact angle (hydrophilicity), and finally the Hansen solubility parameter (HSP) distance between the foulant understudy (BSA protein) and the membrane surface. The HSP distance was investigated as it represented the affinities of materials to each other, and therefore, it was believed to have an important contribution to the tendency of foulant to stick to the surface of the membrane. The results showed that the surface roughness and the HSP distance contributed to membrane fouling more than the hydrophilicity. We recommend taking into account the HSP distance between the membrane material and foulants when selecting membrane materials. Full article

Membrane fouling, a major challenge in desalination, is addressed in this study by investigating three different chemical cleaning protocols (A, B, and C) targeting fouled reverse osmosis (RO) membranes and microbial community composition. Cleaning protocols A and B involve different chemical treatments selected based on preliminary tests and literature review, while protocol C follows the manufacturer’s standard recommendation. Membrane morphology, foulant composition, and microbial community variability in fouled, virgin, and cleaned membranes are studied. Effective biofilm removal is observed across all protocols using scanning electron microscopy (SEM), while spectroscopic techniques highlight interactions between foulants and membranes. Importantly, a critical gap in understanding how cleaning strategies influence microbial communities on membranes is addressed. Shifts in dominant bacterial phyla (Proteobacteria, Firmicutes, and Actinobacteria) after cleaning are identified through 16S rRNA amplicon sequencing. Cleaning A showed the best results in reducing microbial counts and restoring composition similar to virgin membranes. Additionally, chemical treatment increased dominance of resistant genera such as Staphylococcus, Bacillus, Citrobacter, and Burkholderia. This study emphasizes the necessity for tailored fouling cleaning strategies for RO membranes, with Cleaning A is a promising solution, paving the way for enhanced water purification technologies. Full article

Wastewater treatment plants produce high quantities of excess sludge. However, traditional sludge dewatering technology has high energy consumption and occupies a large area. Dead-end forward osmosis (DEFO) is an efficient and energy-saving deep dewatering technology for sludge. In this study, the reverse osmosis of salt ions in the draw solution was used to change the sludge cake structure and further reduce its moisture content in cake by releasing the bound water in cell. Three salts, NaCl, KCl, and CaCl₂, were added to the excess sludge feed solution to explore the roles of the reverse osmosis of draw solutes in DEFO. When the added quantities of NaCl and CaCl₂ were 15 and 10 mM, respectively, the moisture content of the sludge after dewatering decreased from 98.1% to 79.7% and 67.3%, respectively. However, KCl did not improve the sludge dewatering performance because of the “high K and low Na” phenomenon in biological cells. The water flux increased significantly for the binary draw solute involving NaCl and CaCl₂ compared to the single draw solute. The extracellular polymer substances in the sludge changed the structure of the filter cake to improve the formation of water channels and decrease osmosis resistance, resulting in an increase in sludge dewatering efficiency. These findings provide support for improving the sludge dewatering performance of DEFO. Full article