Techno-economic optimization of large-scale two-stage brackish water reverse osmosis systems using dimensionless modeling.

Reverse osmosis desalination plants are built for worst-case conditions, yet seasonal variations in feed water quality often outpace their design assumptions, leading to avoidable membrane performance losses. Temperature swings of 10–15 °C, along with changes in salinity, organic matter, and microbial activity, drive predictable membrane fouling dynamics that static protocols cannot accommodate. This review synthesizes RO studies published from 2015 to 2025 across hot-desert, Mediterranean, temperate, and tropical climate zones using Köppen-Geiger climate classification as an organizing framework, the first systematic climate-resolved synthesis of seasonal fouling mechanisms and adaptive responses. Through this review, three principal findings emerge. First, climate-specific seasonal fouling regimes are distinct and mechanistically predictable patterns: arid coasts (BWh) experience summer biofouling synergistically amplified by gypsum scaling; temperate systems (Cfa, Dwa) face winter organic fouling from recalcitrant humics despite reduced microbial activity; and tropical intakes (Aw, Am) endure monsoonal pulses that increase both colloidal fouling and dissolved organics by 5–100× relative to dry-season baselines. Second, static protocols impose severe performance penalties: flux decline rates can reach 70–85 %, membrane cleaning frequency doubling, and energy consumption rising despite viscosity-driven efficiency gains in warm periods, demonstrating that single-parameter optimization fails under coupled thermal-chemical-biological forcing. Third, predictive-adaptive systems demonstrate step-change improvements: predictive models enable accurate, real-time antiscalant dosing, while temperature-responsive pretreatment maintains higher permeate flux and reduces energy demand by up to nearly 20 %; quorum-sensing-inhibitor coatings reduce biofilm thickness by 60–69 %; and ceramic ultrafiltration eliminates harmful-algal-bloom capacity losses that degrade polymeric membranes by 30–40 %. Yet critical gaps persist hot-arid (BWh) and Mediterranean (Csa) zones, most monitoring datasets are short-term, and temperature-dependent fouling relationships remain unclear due to inconsistent findings. Closing these gaps requires multi-year monitoring across all climate zones and economic validation under climate variability. Seasonal adaptation must evolve from reactive adjustment to fundamental design criterion. Future installations should align membrane materials, pretreatment systems, and control algorithms with site-specific hydrological calendars.

This study challenges the conventional explanations for the failure of Türkiye’s ambitious $21 billion Peace Water Pipeline Project (1986–1995) by demonstrating that technological disruption, rather than geopolitical obstacles, fundamentally undermined this transboundary water initiative. While traditional analyses emphasize political tensions, our research reveals that the concurrent rapid advancement of desalination technology decisively altered the strategic calculus of potential recipient nations, particularly Gulf Cooperation Council countries. Through a comparative case study analysis of Saudi Arabia and the UAE from 1985–1995, we document how these nations systematically rejected pipeline dependence in favor of a domestic desalination capacity that offered superior strategic autonomy, cost competitiveness, and operational flexibility. The study demonstrates that desalination technology improvements during this critical decade—including energy consumption reductions from 20–25 kWh/m 3 to 8–12 kWh/m 3 for reverse osmosis systems and production cost declines from $2.50–3.50/m 3 to $1.00–1.50/m 3 —made domestic water production economically viable while eliminating dependencies inherent in transboundary pipeline projects. Our analysis reveals that Gulf states were willing to pay significant “sovereignty premiums” for water independence, gaining complete control over supply security and protection from political manipulation of water access. The findings contribute to a broader understanding of how technological innovation functions as an independent agent in international resource diplomacy, reshaping cooperative frameworks more decisively than traditional diplomatic negotiations. This case illuminates critical lessons for contemporary water security challenges, demonstrating how emerging technologies can rapidly obsolete large-scale infrastructure projects during their planning phases.

This study evaluates integrated shipboard freshwater production and fresh air pretreatment on a 20,000 TEU-class container vessel, addressing its freshwater demand and the inefficient recovery of exhaust waste heat from the main engine. The system integrates rotary dehumidification, seawater condensation, and water purification. A theoretical model was developed to evaluate the system performance, incorporating design, thermodynamic modeling, parameter optimization, and adaptability analyses under various operating conditions. The results indicate that under optimal conditions (seawater at 25 °C, outlet temperature difference of 2 °C), the single-stage system is predicted to produce approximately 1.45 m3 of freshwater per day, meeting 20.7% of the vessel’s freshwater requirement. The auxiliary electrical energy consumption, estimated based on standard engineering correlations, is 1–1.5 kWh/m3, representing a 70–80% reduction compared to conventional reverse osmosis systems (3–6 kWh/m3). The sensitivity coefficient for seawater temperature was −0.334, whereas that for output temperature was −0.167. A two-stage series configuration has the potential to further improve the demand satisfaction rate to 41–61%. Overall, the proposed system enables the cascade utilization of ship waste heat and functional integration of air pretreatment and freshwater production, offering a promising auxiliary engineering solution for energy conservation, emission reduction, and onboard freshwater self-sufficiency in marine applications.

Accurate modeling of seawater thermophysical and thermodynamic properties is critical for optimizing desalination processes. This study compares three seawater property models, a Reaktoro multicomponent model, the thermophysical seawater properties library from the Massachusetts Institute of Technology, and a simplified sodium chloride model, in the context of levelized cost of water (LCOW) minimization for reverse osmosis (RO) and mechanical vapor compression systems. Process simulations and cost optimizations reveal that although all three models yield comparable LCOW and specific energy consumption (SEC) estimates under baseline conditions, deviations among their predictions increase with salinity. Relative differences in LCOW and SEC reach up to 6% and 8%, respectively. RO results show greater variability due to differences in osmotic pressure predictions, which affect pressure constraints at high recoveries. Computational performance varies substantially; specifically, Reaktoro simulations are up to 28 times slower than empirical models due to their detailed equilibrium calculations. These results suggest that empirical models offer acceptable accuracy for routine desalination process design, while Reaktoro provides advantages in scenarios requiring detailed speciation, such as scaling or pH adjustment studies. These findings underscore the importance of selecting appropriate property models based on the modeling objective of desalination applications and motivate future work integrating thermodynamic rigor with empirical efficiency.

Freshwater scarcity remains a critical challenge in small island regions, particularly in archipelagic countries such as Indonesia, where seawater is abundant but access to clean freshwater is limited. Tunda Island, located in Serang Regency, Banten Province, exemplifies this condition, as local communities primarily depend on rainwater harvesting and shallow groundwater sources to meet daily water demands. This study aims to evaluate a modified reverse osmosis (RO) desalination system integrated with coconut shell–based activated carbon as an adsorptive pretreatment medium for seawater desalination. The coconut shell adsorbent was employed to enhance pretreatment efficiency and improve the overall performance of the RO system. Seawater samples collected from Tunda Island were processed through the integrated system, and the quality of the treated water was evaluated according to the Indonesian Ministry of Health standards. Key parameters analyzed included Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Dissolved Solids (TDS), Total Suspended Solids (TSS), pH, color, and temperature. The results demonstrated that the treated water achieved COD of 120.10 mg/L, BOD of 10.5 mg/L, TSS of 3.76 mg/L, TDS of 117.245 ppm, pH of 7.30, clear color, and a temperature of 27°C, indicating compliance with applicable water quality standards. These findings confirm that the integration of coconut shell–based activated carbon with reverse osmosis effectively improves desalination performance and produces freshwater suitable for domestic use.

Double filament feed spacers for enhanced performance in reverse osmosis modules.

The increasing demand for distilled water (Aquades) in pharmaceutical and medical applications contrasts sharply with the limited quality of municipal water supplies and the high operating costs of commercial Aquades procurement. At the same time, many small-scale facilities still lack integrated systems capable of meeting the Indonesian Ministry of Health standard (Permenkes RI No. 32/2017). Existing research on reverse osmosis (RO) systems largely focuses on membrane or filtration performance, with limited attention to real-time water-quality monitoring and systematic optimization of pre-treatment filters. This study develops an integrated filtration and monitoring system designed to ensure regulatory compliance while optimizing the composition of pre-treatment materials. The system combines silica sand, activated carbon, and zeolite pre-filters with RO, supported by six analog sensors that continuously monitor pH, turbidity, and Total Dissolved Solids before and after filtration. Validation results show high sensor accuracy, with 99.77% for TDS, 98.10% for pH, and 99.97% for turbidity. Among six tested filter compositions, the 25% silica sand-25% activated carbon-50% zeolite configuration achieves the highest average filtration efficiency of 88.96%. These findings demonstrate that optimized pre-treatment combined with real-time monitoring can significantly improve RO performance and support cost-effective Aquades production for medical use.

This research introduces and optimises a grid-connected hybrid solar-wind system to power a reverse osmosis (RO) desalination unit in Bahrain. A model based on mixed-integer nonlinear programming (MINLP) optimisation framework is developed to design the system and evaluate its performance under Bahrain’s weather conditions. The design and operation of the RO process are optimised while considering fluctuations in water demands, changes in seawater temperature, and renewable energy variations throughout the day. The model determines the optimal operation strategy of flexible RO systems, the ideal number of wind turbines and photovoltaic (PV) modules, and the energy purchased from the grid to operate the RO plant and supply freshwater at a minimum cost. Hourly fluctuations in weather conditions are considered to achieve an efficient design. Two case studies of winter and summer conditions are presented in this research to accommodate different feed water and weather conditions. The levelized cost of water LCOW is found to be $0.751/m³ in summer and $0.648/m³ in winter, demonstrating the cost-effectiveness of the hybrid system, particularly during winter when wind energy is more abundant. The integration of solar and wind power reduces CO2 emissions by an estimated 4.0 tons per day in January (winter) and 3.0 tons per day in June (summer), further enhancing the environmental benefits of the proposed system. The optimisation model successfully determines that maintaining continuous operation of one membrane group while operating a second group intermittently is sufficient to meet freshwater demands, allowing the third group to remain available for maintenance. This operational strategy provides both production efficiency and maintenance flexibility while minimising total system costs.

Freshwater scarcity in southern Xinjiang has intensified the need for effective utilization of saline–alkaline agricultural drainage. This study evaluates pre-treatment technologies for reverse osmosis (RO) systems to improve water quality and mitigate membrane fouling. Three processes were tested: coagulation–sedimentation–media filtration (G1), micro-flocculation–media filtration (G2), and micro-flocculation (G3) combined with ultrafiltration and varying polyaluminum chloride (PAC) dosages (0–15 mg·L−1). Results show that G1 and G2 significantly outperform G3 in removing turbidity, organic matter, and inorganic ions, achieving SDI15 < 5 and turbidity < 0.3 NTU, meeting RO feedwater standards. Optimal performance occurred at the 7.5–10 mg·L−1 coagulant dosage range, effectively controlling flux decline and fouling. The integrated pre-treatment–ultrafiltration system provides a robust technical framework for saline–alkaline water desalination, offering practical guidance for sustainable water resource utilization in arid agricultural regions.

High prevalence of Legionella and multidrug-resistant Pseudomonas in portable hemodialysis RO systems: Implications for infection control.

• HP-POU-RO at ultra-low pressure to produce fresh water. • Field test using off-grid water (India) during 6 months of continuous operation. • An 88.2–93.94 % TDS rejection. • Community Perception Survey on Water Quality and System Usability. This study shows the development and implementation of a novel Hand-Powered Point-Of-Use Reverse Osmosis (HP-POU-RO) purification unit designed to operate under extremely low-pressure conditions (≤0.2 MPa) in off-grid rural environments. The system was tested for six months in Namkhana (West Bengal), using water from a well, and Udaipur (Rajasthan), using water from a cement water reservoir tank. The raw water exhibited Total Dissolved Solids (TDS) levels ranging from 680 to 1080 mg L⁻¹, representative of moderately brackish conditions. The HP-POU-RO unit integrates a 3-inch RO module identified as HA002 and HA003, each made up of a new cellulose nanofiber composite membrane. These RO modules were coupled to a manual piston-driven mechanism that converts human effort into hydraulic pressure to drive the reverse osmosis process. Results showed TDS rejection rates of 88.2 % for HA002 and 93.94 % for HA003, with specific energy consumption (SEC) values ranging from 0.18 to 0.20 kWh m⁻³. In comparison, a commercial polyamide (PA) RO module (HA004) exhibited a slightly higher TDS rejection rate of 95.25 % but required significantly more SEC (0.38–0.40 kWh m⁻³). These findings confirm the high energy efficiency and operational stability of the HA002 and HA003 RO in prolongated manual operation. A community perception survey revealed strong social acceptance, reporting satisfaction with water taste, clarity, and perceived health benefits. Findings suggest that the HP-POU-RO unit is a sustainable technological solution for providing safe drinking water from off-grid systems, with potential for wider deployment in remote or infrastructure-limited regions.

This presentation will discuss the development of a portable water purification and desalting system to address water insecurity in regions with limited basic water infrastructure, water contamination, or frequent interruptions caused by climate change or natural disasters. Current membrane desalination technologies, such as reverse osmosis (RO) and electrodialysis (ED), are more suitable for urban areas than for resource-limited environments or places sensitive to natural disasters, e.g., flood or drought [2]. Most of the few commercially available portable RO systems require high-pressure pumping and water preconditioning before purification. RO systems are also prone to membrane fouling and require continuous maintenance, which limits deployment flexibility and adds to the total system cost. ED systems have higher energy loss than RO systems, especially for high salinity water purification [2-4]. Even with advancements in low-resistance membranes to improve power efficiency, ED systems still struggle to avoid ion diffusion from the concentrated brine and to remove microparticles (e.g., microplastics) [3]. Thus, alternative point-of-use water purification systems are urgently needed.We have developed a water desalting and purification method that employs a nonlinear electrokinetic phenomenon to divert charged species (salts, molecular ions, bacteria, microplastics) from flowing feedwater into a physically separated waste stream. This electrokinetic phenomenon, ion concentration polarization (ICP), occurs when a voltage bias is applied across ion-selective features such as electrodes or highly charged membranes. This process selectively transports ions, subsequently creating ion depletion and enrichment zones (IEZ & IDZ) at the opposing ends of the ion-selective feature. For water desalination, ICP captures or redirects charged particles at the boundary between the background electrolyte and the IDZ, effectively removing not only salts but also bacteria and oil-in-water emulsions with negative zeta potential. While planar membrane-based desalination using ICP has been demonstrated, its throughput is insufficient for practical use due to the instability of the electric field and electroconvective vortices generated. Figure 1

Groundwater quality in urban region is increasingly at risk due to the combined effects of urban sprawl, microclimatic conditions, and large sewage generation. Domestic Reverse Osmosis (RO) systems are unable to remove nitrate and sulphate in drinking water, and leads to human health hazards. This study focuses on prediction of nitrate and sulphate levels in groundwater through integrating microclimatic conditions with urban expansion indicators. A hybrid modeling approach has been developed using an Attention-based Convolutional Neural Network (ACNN) and Bayesian Optimized Multiple Linear Regression (BO-MLR). Sentinel satellite image is used for extraction of spectral band features, with attention scores highlights the most relevant indices for groundwater contamination. The above features have been combined with field-based measurements from sprawl-affected areas in the Chengalpattu region. To refine the dataset, the FP-Growth algorithm has been applied to identify strong associations between sprawl indicators and contaminant concentrations. The BO-MLR model has achieved prediction 95% of accuracy in detection of Nitrate and Sulphate levels in drinking water, closely match to the laboratory observations. Results shows that groundwater nitrate and sulphate level increases significantly with increase in urban sprawl, with 50% increase in built-up area linked to approximately 75% higher nitrate and 60% higher sulphate levels in groundwater. The above findings highlight the urgent need for sustainable urban planning and groundwater management strategies, provides awareness and hazardous zones in Chengalpattu area.

This research presents a new method to reduce the environmental impact of reverse osmosis (RO) systems in solar farms. The concept involves enhancing the connection between water, energy, and the environment by utilizing an RO system that is powered by an organic Rankine cycle (ORC), which produces electricity using heat from a solar field. The study examines various ORC setups and operating fluids based on energy analysis (1E), exergy (2E), economic (3E), and environmental effects (4E) to create clean water. Important aspects of the optimization process include selecting the ORC setup, picking the working fluid for the ORC, and establishing the design parameters for the solar parabolic farm. These parameters are fine-tuned using a genetic algorithm technique. The findings show a 12% decrease in environmental impact and a 7.5% improvement in exergy efficiency due to this three-objective optimization strategy.

This study evaluates desalination technologies’ environmental and economic performance by comparing the Ras Al-Khair and Shoaiba desalination plants in Saudi Arabia. The primary objective is to integrate Life Cycle Assessment (LCA) and cost analysis to assess the sustainability of Reverse Osmosis (RO), Multi-Stage Flash (MSF), and hybrid desalination systems. The results reveal significant differences in energy consumption, global warming potential (GWP), brine disposal management, and resource depletion. Using a hybrid RO/MSF system, Ras Al-Khair demonstrates substantially lower energy demands (3–5 kWh/m³) and a reduced carbon footprint, capturing 300,000 tons of CO2 annually. In contrast, Shoaiba’s MSF system, relying on crude oil for power generation, generates higher energy consumption (13–15 kWh/m³) and 8.2 million tons of CO₂ emissions annually. The economic analysis highlights Ras Al-Khair’s higher initial capital expenditure (CAPEX) of $7.6 billion but lower operational costs ($0.65/m³) and a faster break-even period (12 years) compared to Shoaiba’s $1.60/m³ cost and a break-even period of 18 years. The study emphasizes integrating energy recovery, carbon capture, and renewable energy solutions in sustainable desalination practices to address global water scarcity while minimizing environmental impact and enhancing economic feasibility.

This paper addresses the pressing issue of water quality assurance under increasing anthropogenic pressure. The efficiency of reverse osmosis (RO) technology for water purification, particularly in the pharmaceutical industry, is analyzed. Data concerning the impact of key operational parameters (pressure, recovery rate) and physico-chemical characteristics of feedwater (pH, hardness, alkalinity) on membrane purification efficiency are systematized. Particular attention is given to the problems of membrane scaling, especially in regions with high concentrations of hardness salts. Methods for assessing water's scaling tendency (LSI, SDI indices), monitoring strategies, and water pre-conditioning, including antiscalant dosing (phosphonates, polyacrylic acid) and pH adjustment, are examined. Modern approaches to optimizing RO systems, such as the use of digital twins and hybrid technologies (RO-UV, RO-ED), which contribute to improved purification quality, energy efficiency, and reduced fouling risks, are also highlighted. Recommendations are proposed for optimizing operational parameters, developing water stability assessment methodologies, and implementing monitoring systems to ensure the long-term efficiency of reverse osmosis systems.

A closed-form analytical model for estimating permeate salinity in reverse osmosis systems

Evaluation of performance and practicality of small- to medium-scale photovoltaic solar-powered reverse osmosis systems for brackish water desalination: A review

Currently, thermal power plants make the largest contribution to the production of electricity. In order to compensate for the loss of steam and condensate, many thermal power plants use membrane methods, such as reverse osmosis systems, to prepare additional water. However, the use of reverse osmosis systems results in the production of highly mineralized concentrate, which cannot be discharged into surface water bodies or sewage systems without prior treatment. The article discusses the possibility of using reverse osmosis concentrate from thermal power plants as mineralized water for injection into oil reservoirs in order to increase the oil displacement coefficient.