Reverse Osmosis Research Articles

Construction of energy consumption monitoring system for energy saving equipment in seawater desalination based on whale algorithm

ABSTRACT Seawater desalination has emerged as a pivotal solution to address freshwater scarcity in coastal regions, with China being a prominent adopter of this technology. This paper compares three large-scale seawater desalination projects in China: the Six Heng Water Treatment Plant, the Caofeidian Desalination Project, and the Huaihai Yu Huan Power Plant Desalination Project. Each project employs distinct desalination technologies, including reverse osmosis and dual-membrane processes. We evaluate these systems’ operational parameters, performance indicators, and cost-effectiveness over their operational lifespans. Key considerations include seawater intake, pretreatment processes, reverse osmosis desalination, energy recovery systems, and post-treatment mineralisation. The analysis highlights these desalination plants’ efficiency, sustainability, and economic viability in addressing freshwater demands in their respective regions. Insights from this comparative study contribute to optimising seawater desalination processes, enhancing water resource management, and guiding future infrastructure development efforts in coastal areas.

Reverse Osmosis Coupled with Ozonation for Clean Water Recovery from an Industrial Effluent: Technical and Economic Analyses

Reverse Osmosis Coupled with Ozonation for Clean Water Recovery from an Industrial Effluent: Technical and Economic Analyses

Spacer Designs for Improved Hydrodynamics and Filtration Efficiency in Sea Water Reverse Osmosis

Spacer Designs for Improved Hydrodynamics and Filtration Efficiency in Sea Water Reverse Osmosis

Orientation-Dependent Anisotropic Desalination by Assembled Zeolite Nanotube Membranes.

Porous nanomaterials have shown great promise in many desalination applications. Zeolite nanotubes, featuring abundant but inhomogeneous nanopores on their surface, have been recently synthesized in experiments; however, their capacity for desalination is not yet understood. In this work, we use molecular dynamics simulations to investigate the capability of assembled zeolite nanotube membranes to perform in desalination applications due to their inherent multiscale porous properties. Two different membrane assemblies are examined to determine the effect of membrane orientation on desalination performance. Interestingly, we find that zeolite nanotube membranes present anisotropic desalination behavior, which is directly dependent on the assembled orientation of the zeolite nanotubes. Specifically, directing the transport through the axial channels of the nanotubes results in a water permeability of 59.8 L/cm2/day/MPa and 88% ion rejection. However, when the membrane is rotated 90° and the flow is directed perpendicular to the tube axis, the permeability drops to 22.3 L/cm2/day/MPa, but 100% ion rejection is achieved. This difference is attributed to the multiscale pore dimensions of the zeolite nanotube; that is, they possess large pores (a diameter of 3 nm) along the axial channel direction, but smaller pores (a diameter of 0.25 nm) along the direction perpendicular to the tube axis. The ion rejection capabilities are further verified by quantifying the free energy barriers to transport obtained via umbrella sampling simulations. Therefore, our findings demonstrate the orientation-dependent, anisotropic desalination performance in assembled zeolite nanotube membranes for the first time, which could be useful in designing future advanced desalination membranes.

Experimental Investigation on Thermo-Economic Analysis of Direct Contact Membrane Distillation for Sustainable Freshwater Production

Treatment of extremely saline water such as the brine rejected from reverse osmosis water desalination plants, and produced water from shale oil and non-conventional gas extraction, is considered a global problem. Consequently, in this work, hollow fiber membrane distillation (HFMD) is experimentally evaluated for desalinating extremely saline water of a salinity ranging from 40,000 to 130,000 ppm. For the purpose of comparison, the HFMD is also tested for desalinating brackish (3000–12,000 ppm) and sea (25,000–40,000 ppm) water. Firstly, the HFMD is tested at two values of feed water temperature (65 and 76 °C) and flow rate (600 and 850 L/h). The experimental results showed that the HFMD productivity significantly increases when the temperature of feed water increases. Increasing the feed water flow rate also has a positive effect on the productivity of HFMD. It is also concluded that the productivity of the HFMD is not significantly affected by increasing the salt concentration when brackish and sea water are used. The productivity also slightly decreases with increasing the salt concentration when extremely saline water is used. The decrement in the productivity reaches 27%, when the salt concentration increases from 40,000 to 130,000 ppm. Based on the conducted economic analysis, the HFMD shows a good potential for desalinating extremely saline water especially when the solar collector is used as a heat source. In this case, the cost per liter of freshwater is reduced by 21.7–23.1% when the evacuated tube solar collectors are used compared to the system using electrical heaters. More reduction in the cost per liter of freshwater is expected when a high capacity solar-powered HFMD plant is installed.

Diatom-Based Photobiological Treatment of Reverse Osmosis Concentrate: Optimization of Light and Temperature and Biomass Analysis

As global water scarcity intensifies, the desalination of brackish groundwater and surface water plays a critical role in augmenting water supplies. However, managing reverse osmosis concentrate (ROC) from brackish water desalination remains challenging due to silica and calcium accumulation and precipitation, which cause membrane scaling and reduce freshwater recovery. This study employed the brackish diatom Gedaniella flavovirens Psetr3 in a photobiological treatment to remove dissolved silica and calcium, offering a natural, sustainable solution to improve freshwater recovery. Optimal treatment conditions were identified, with a light intensity of 200 µmol m−2 s−1 and incubation temperatures between 23 °C and 30 °C maximizing silica uptake (up to 46 ± 3 mg/L/day) while minimizing diatom mortality. This study reports, for the first time, the silica, organic, and calcite content in diatom biomass and their production rates during the photobiological treatment of ROC using G. flavovirens Psetr3. The photobiological treatment of one million gallons (3785 m3) per day of ROC would produce 174 kg of silica, 163 kg of organics, and 314 kg of calcite daily. These findings provide valuable insights into the potential for utilizing these bioresources to offset the costs of photobiological treatment and subsequent desalination processes.

Novel Co-Polyamides Containing Pendant Phenyl/Pyridinyl Groups with Potential Application in Water Desalination Processes

This study explores the development and evaluation of a novel series of aromatic co-polyamides featuring diverse pendant groups, including phenyl and pyridinyl derivatives, designed for water desalination membrane applications. These co-polyamides, synthesized with a combination of hexafluoroisopropyl, oxyether, phenyl, and amide groups, exhibited excellent solubility in polar aprotic solvents, thermal stability exceeding 350 °C, and the ability to form robust, flexible films. Membranes prepared via phase inversion demonstrated variable water permeability and NaCl rejection rates, significantly influenced by the pendant group chemistry. Notably, pyridinyl-substituted membranes achieved water fluxes up to 17.7 L m−2 h−1 and a NaCl rejection of 37.3%, while phenyl-substituted variants provided insights into the interplay of hydrophobicity and porosity. These findings highlight the critical role of pendant group functionality in tailoring membrane performance, offering a foundation for further structural modifications to enhance efficiency in water treatment technologies.

Study on the effect of water content on physical properties of bentonite.

Moisture content profoundly influences the engineering properties of expansive soil, a critical consideration in various geotechnical applications. This study delves into the intricate relationship between water content and the physical properties of bentonite, a key constituent of expansive soil. Through a comprehensive analysis encompassing fundamental physical properties, rheological characteristics, permeability behavior, and microscopic features, we elucidate the complex interplay between water content and bentonite behavior. Our investigation reveals distinct responses to varying moisture levels: at low water content (w = 50%), unsaturated samples undergo incremental density increases attributed to moisture accumulation among particles. Concomitantly, heightened pressure fosters enhanced cohesion between particles, bolstering mechanical properties and augmenting reverse osmosis capacity. Conversely, at higher water content levels (w > w saturated), the escalation of free water within soil particles triggers pronounced particle softening, overshadowing expansion effects. Consequently, cohesion diminishes, and particles exhibit micro-scale flocculation. These findings offer valuable insights into bentonite behavior under differing moisture regimes, thereby providing a robust theoretical foundation for projects requiring bentonite seepage control.

Volatile Sieving Using Architecturally Designed Nanochannel Lamellar Membranes in Membrane Desalination.

Thermally driven membrane desalination processes have garnered significant interest for their potential in the treatment of hypersaline wastewater. However, achieving high rejection rates for volatiles while maintaining a high water flux remains a considerable challenge. Herein, we propose a thermo-osmosis-evaporation (TOE) system that utilizes molecular intercalation-regulated graphene oxide (GO) as the thermo-osmotic selective permeation layer, positioned on a hydrophobic poly(vinylidene fluoride) fibrous membrane serving as the thermo-evaporation layer. By carefully constructing architectural interlaminar nanochannels of GO membranes via simultaneously confining small molecules to enlarge the interlayer spacing and incorporating polymers within the GO interlayers to create a dense network, the resultant demonstrates a rejection rate of 100% for NaCl and 97.41% for volatile phenylamine, with a water permeance of 63.80 L m-2 h-1 at a temperature difference of 40 °C, outperforming previously reported GO-based membranes. Simulation and calculation results reveal that the polymer network between the GO interlayers facilitates the high-efficiency separation of nonvolatile ions and volatile molecules, while the enlarged channels reduce vapor diffusion resistance. This study provides valuable insights for the design of advanced membranes and serves as inspiration for the continued development of the TOE system for complex hypersaline wastewater treatment.

Characterization and Environmental Impact of Produced Water from Oil Fields in the Sirte Basin, Libya

This study evaluates the characteristics and environmental implications of produced water discharged from Zaltan, Al-Lahib, and Al-Jabal oil fields in the Sirte Basin, Libya. The fields collectively produce 217,800 barrels of untreated produced water daily, containing exceptionally high levels of total dissolved solids (TDS) ranging from 40,000 ppm (Zaltan) to 160,000 ppm (Al-Lahib). Elevated concentrations of heavy metals, including mercury (100 mg/L), iron (105 mg/L), and lead (65 mg/L) in Al-Lahib, far exceed safe environmental limits. Inorganic ions such as chloride (26,658 mg/L), nitrate (10,034 mg/L), and bicarbonate (12,806 mg/L) contribute to significant salinization and groundwater contamination risks. These findings highlight the severe environmental impact of produced water discharge, including soil degradation, ecosystem disruption, and threats to public health. Implementing advanced treatment technologies, such as reverse osmosis, electrocoagulation, and constructed wetlands, is recommended to mitigate these risks and ensure sustainable water management.

The Role of Membranes in Modern Winemaking: From Clarification to Dealcoholization

The utilization of membrane technologies in winemaking has revolutionized various stages of production, offering precise and efficient alternatives to traditional methods. Membranes, characterized by their selective permeability, play a pivotal role in enhancing wine quality across multiple processes. In clarification, microfiltration and ultrafiltration membranes, such as ceramic or polymeric membranes (e.g., polyethersulfone or PVDF), effectively remove suspended solids and colloids, resulting in a clearer wine without the need for chemical agents. During stabilization, membranes such as nanofiltration and reverse osmosis membranes, often made from polyamide composite materials, enable the selective removal of proteins, polysaccharides, and microorganisms, thereby improving the wine’s stability and extending its shelf life. Additionally, in dealcoholization, membranes like reverse osmosis and pervaporation membranes, typically constructed from polydimethylsiloxane (PDMS) or other specialized polymers, facilitate the selective removal of ethanol while preserving the wine’s flavor and aroma profile, addressing the increasing consumer demand for low-alcohol and alcohol-free wines. This article provides a comprehensive analysis of the advancements and applications of membrane technologies in winemaking.

Reverse osmosis membrane fouling caused by typical surfactants in the integrated circuit industry: Fouling mechanism and control strategies.

In the integrated circuit manufacturing process, reverse osmosis (RO) membranes are widely used for wastewater reclamation. However, fouling by typical surfactants significantly reduces membrane efficiency and lifespan. This study investigates the fouling mechanisms of typical surfactants-cetyl trimethyl ammonium bromide (CTAB, cationic), sodium dodecyl sulfate (SDS, anionic), and polyoxyethylene octyl phenyl ether (TX, nonionic)-on RO membranes. Quartz crystal microbalance analysis results show that CTAB and TX exhibit significantly stronger adhesion to RO membranes than SDS. The order of adsorption mass on the membrane surface is CTAB > TX > SDS, with CTAB causing the most severe fouling. Molecular dynamics (MD) simulations indicate that unclustered CTAB molecules contribute to severe fouling by inserting into the membrane surface. As surfactant concentration increases, clustered CTAB is less likely to enter the membrane's surface layer. A comparison of oxidative technologies-continuous dual-wavelength ultraviolet (VUV/UV), intermittent VUV/UV, and intermittent VUV/UV with chlorine, ozone alone, chlorine alone, and ozone combined with chlorine (ozone/chlorine)- reveals that pre-treating surfactants with ozone/chlorine (simultaneous dosing at 10 mg/L each) before membrane filtration effectively controls fouling. After 30 min of treatment, 29 % of CTAB and 86 % of TX were degraded, respectively. Ozone/chlorine oxidation significantly alleviates membrane fouling, increasing the normalized steady-state permeate flux (Jpss) of CTAB and TX by 245 % and 151 %, respectively. The extended Derjaguin-Landau-Verwey-Overbeek theory calculations and MD simulations show that oxidation weakens the adhesion of CTAB and TX to RO membranes, reducing fouling. Ozone/chlorine treatment also effectively mitigates membrane fouling in actual wastewater from the electronics industry. Post-oxidation, the flux ratio (J/J0) increased from 0.28 to 0.52, resulting in a 116.7 % improvement in the Jpss. This study combines experimental data, theoretical calculations, and MD simulations, highlighting the significance of molecular clustering in surfactant-induced fouling before and after oxidation.

Evaluation of fouling and chemical cleaning of reverse osmosis membrane after treatment of geothermal water

Evaluation of fouling and chemical cleaning of reverse osmosis membrane after treatment of geothermal water

Wind desalination and power: an affordable and renewable solution to address water shortages

ABSTRACT There has been a steep increase in investment in more affordable approaches to desalinated seawater using renewable energy sources. This paper proposes desalinating seawater with a pump and a motor-generator installed inside wind turbine nacelles, to desalinate seawater with reverse osmosis membranes without electricity. The technology was named Wind Desalination and Power (WDP), as the wind turbine can pump seawater and generate electricity. This study presents a comprehensive analysis and rationale behind the design, estimates its economic viability, and assesses the global potential of the proposed technology. Results demonstrate that the cost for seawater desalination with WDP is 0.64 USD/m3, which is 20% cheaper than conventional wind desalination. The paper shows that WDP has the potential to enhance water resilience in arid regions while at the same time contributing to grid stability and renewable energy integration.

Unraveling the Atomistic Mechanisms Underlying Effective Reverse Osmosis Filtration by Graphene Oxide Membranes.

The graphene oxide (GO) membrane displays promising potential in efficiently filtering ions from water. However, the precise mechanism behind its effectiveness remains elusive, particularly due to the lack of direct experimental evidence at the atomic scale. To shed light on this matter, state-of-the-art techniques are employed such as integrated differential phase contrast-scanning transmission electron microscopy and electron energy loss spectroscopy, combined with reverse osmosis (RO) filtration experiments using GO membranes. The atomic-scale observations after the RO experiments directly reveal the binding of various ions including Na+, K+, Ca2+, and Fe3+ to the defects, edges, and functional groups of GO. The remarkable ion-sieving capabilities of GO membranes are confirmed, which can be attributed to a synergistic interplay of size exclusion, electrostatic interactions, cation-π, and other non-covalent interactions. Moreover, GO membranes modified by external pressure and cation also demonstrated further enhanced filtration performance for filtration. This study significantly contributes by uncovering the atomic-scale mechanism responsible for ion sieving in GO membranes. These findings not only enhance the fundamental understanding but also hold substantial potential for the advancement of GO membranes in reverse osmosis (RO) filtration.

Inhibition of calcium carbonate scaling in reverse osmosis by Zn++ using pure calco-carbonic solutions and the membrane CO2 degassing method

Inhibition of calcium carbonate scaling in reverse osmosis by Zn++ using pure calco-carbonic solutions and the membrane CO2 degassing method

Water transport mechanisms during pressure-driven transport through polyamide nanogaps.

Molecular-scale simulations of pressure-driven transport through polyamide nanogaps (5-100 Å) were performed to investigate fundamental transport mechanisms. Results show that transport in nanogaps 10 Å is always subdiffusive, but superdiffusive transport was observed in nanogaps 20 Å. Near typical operating pressures for applications ( = 100 atm), only the 100 Å nanogap exhibited superdiffusive behavior. Since openings in common membrane materials are typically <20 Å, results indicate that subdiffusive to diffusive transport dominates for typical applications, such as reverse osmosis.

POLYAMIDE REVERSE OSMOSIS MEMBRANES MODIFIED WITH GRAPHENE OXIDE FOR ENHANCED CHLORINE ATTACK AND FOULING RESISTANCE

Reverse osmosis (RO) systems are an essential tool for water desalination, but their effectiveness can be hampered by membrane fouling and susceptibility to chemical degradation from free chlorine. Polyamide (PA)...

Incorporating convection into the solution-diffusion framework enhances modeling accuracy in reverse osmosis

Incorporating convection into the solution-diffusion framework enhances modeling accuracy in reverse osmosis

Review of the recent six-year chlorination resistance strategies of polyamide reverse osmosis and nanofiltration membrane

Review of the recent six-year chlorination resistance strategies of polyamide reverse osmosis and nanofiltration membrane