Reverse osmosis treatment of blow-down water for beneficial reuse and sustainable power generation

A combined approach for studying water quality, attitudes, and practices is presented, focusing on urban low- and middle-income households in Chennai, India using reverse osmosis (RO) systems. Challenging the common assumption that in-home water treatment particularly RO fully resolves drinking water safety issues, this article presents one of the first empirical evaluations of the effectiveness of household-level filtration methods. The study aims to assess the microbial safety of drinking water before and after household RO treatment and to understand how education and awareness influence household water and maintenance practices. The study involved surveys, water sampling, and data analysis, conducted by a multi-disciplinary team from Tel Aviv University, IIT Madras, and local partners. Water samples were collected before and after RO treatment from 216 households (262 samples total), and socio-demographic information, including education levels and water-use behavior, was analyzed. The findings revealed that while RO systems reduce contamination, 31% of post-RO samples still contained E. coli, compared to 71% in untreated water. Furthermore, education levels were found to influence outcomes: 36% of post-RO samples from postgraduate respondents contained E. coli, versus 83% among those with lower education levels. Empirical evaluation of RO system effectiveness in urban Chennai households. 31% of post-RO household samples remained contaminated with E. coli. RO systems reduce contamination but offer limited protection without maintenance. Integrated survey and water testing reveal gaps in treatment efficacy perception. Post-RO contamination linked to respondent education level and user practices.

Water desalination using a multilayer graphene oxide membrane: a molecular dynamics study.

Contrasting effects of biofilm on arsenic removal between activated carbon and reverse osmosis point-of-use water filtration systems.

Salinity is a key parameter for bacterial survival and growth. Halophilic and halotolerant bacteria can adapt to elevated salinity, but the energetic demands of osmoadaptation increase under fluctuating salt concentrations, potentially constraining growth and persistence. A new concept in reverse osmosis (RO) filtration is batch operation with oscillating rather than constantly high brine salinity. We hypothesize that fluctuating salinity can diminish biofouling in such RO systems. To test this hypothesis, we examined the survival and activity of Aliivibrio fischeri and Pseudomonas fluorescens under fluctuating salinities in planktonic and biofilm cultures as representative of halophilic and halotolerant species, respectively, and common members of biofouling communities. At 28°C, P. fluorescens grew at 0%-6% salinity with fastest growth rate at 0%-1%. At 7%-10% salinity, P. fluorescens remained viable but did not grow. At 22°C, A. fischeri grew at 0.5%-7% salinity, with fastest growth rate at 2%-3%, but unlike P. fluorescens, it lost viability outside this growth range. Cultures did not respire at salinities that did not support growth, suggesting that survival under such salt stress does not depend on high metabolic activity. Furthermore, cell-specific aerobic respiration rates in A. fischeri correlated with growth rate but not osmotic stress. Biofilm formation did not enhance the osmotic stress tolerance of the two bacteria. Our results indicate that high constant salinity favors the halophilic A. fischeri over the halotolerant P. fluorescens, but oscillating salinity (e.g., 0%-7%) favors neither. Oscillating salinity may, therefore, offer a new mechanism for controlling microbial growth that circumvents community adaptation to environmental conditions.IMPORTANCEReverse osmosis filtration is a widely used technology to address the scarcity of clean freshwater. However, the efficiency of reverse osmosis systems is challenged by microbial biofouling, as microbial communities adapt to the environmental conditions within the system and form biofilms on the membranes. This study investigated the impact of fluctuating salinity on the growth and survival of halophilic and halotolerant bacteria. The findings suggest that oscillating salinity disrupts the growth and viability of both types of bacteria, in both planktonic cultures and biofilms. The study, thus, supports the hypothesis that fluctuating salinity in reverse osmosis systems could reduce biofouling by impeding microbial adaptation to salinity. This represents a promising new strategy for microbial control in reverse osmosis systems, potentially enhancing performance by minimizing biofouling through an environmentally friendly approach.

This work presents the most recent advancements and operational experiences obtained with the large-active-area, high-rejection FilmTec™ SW30HR-380 and SW30HR-320 reverse osmosis membrane elements, with particular focus on their techno-economic implications, especially regarding energy demand and potential operational cost reductions. The study also examines fouling prevalence and reviews the latest developments in technical mitigation strategies, with emphasis on the new wide-spacer SW30HR-320 elements designed for open-intake applications. Overall, the findings indicate that these new membrane products constitute an effective option for the design of seawater reverse osmosis systems treating both clean and fouling-prone feedwaters. The techno-economic evaluation demonstrates that the adoption of these elements can enable reductions of approximately 20% in capital expenditures, up to 25% in energy consumption, and up to 4% in cleaning-related costs-including downtime-when the SW30HR-320 is operated under high-fouling feedwater conditions.

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

Bridging environmental and economic dimensions: A comparative techno-economic analysis of reverse osmosis and microalgae-based systems for hypersaline produced water treatment

The increasing scarcity of freshwater resources underscores the strategic importance of seawater desalination. However, optimizing reverse osmosis (RO) systems remains challenging because of raw water variability, high energy consumption, and membrane degradation. This study investigates the use of artificial intelligence (AI) for predictive monitoring of the Cap Djinet desalination plant (Boumerdès, Algeria), based on real operational data. Six supervised learning algorithms, linear regression (LR), polynomial regression (PR), support vector regression (SVR), random forest (RF), extreme gradient boosting (XGBoost), and multilayer perceptron (MLP), were evaluated for predicting the physicochemical and chemical parameters of the produced water. The findings indicate that ensemble models, particularly XGBoost (R2 = 0.999; RMSE = 6.11; MAPE = 2.23%), outperform other methods, followed by RF and SVR. Although simple, the LR model demonstrated strong robustness (R2 = 0.999; RMSE = 4.90), making it suitable for daily operation. The analysis further indicates that the performance of complex models, such as the MLP, is strongly influenced by the limited sample size (MAPE = 65.45%), illustrating the sensitivity of deep learning approaches in small-data contexts. While this frames the applicability of the results within the scope of the available dataset, it remains representative of the operational conditions commonly encountered in desalination plants with restricted yet meaningful datasets. Overall, XGBoost, RF, SVR, and LR demonstrate significant potential for predictive monitoring and sustainable optimization of desalination processes.

Industrial Deployment of a Decision-Oriented Digital Twin for Predictive Maintenance of a Reverse Osmosis System: An End-To-End Case Study in a Beverage Filling Plant

Produced water from oil and gas operations contains extremely high salinity (100,000–300,000 mg/L), far exceeding the treatment limits of conventional reverse osmosis systems. This study presents a techno-economic analysis of four clathrate hydrate-based desalination (CHD) configurations treating 750 ton/h of produced water (10 wt % salinity, 40% recovery): (1) Methane (No Recycle), (2) HFC-152a (No Recycle), (3) HFC-152a (Recycle), and (4) HFC-152a Recycle with Cold Energy Integration. Substituting HFC-152a for methane reduces the fixed capital investment (FCI) from $227.44 million to $96.80 million (−57.4%) due to a decrease in formation pressure from 8.0 to 0.25 MPa. Incorporating gas recycling further lowers the FCI to $71.93 million (−25.7%) by eliminating the need for fresh gas compression. Integrating LNG cold energy yields the largest reduction, achieving an FCI of $17.97 million (−75.0%) by replacing mechanical refrigeration with passive cryogenic heat exchange. The levelized cost of water (LCOW) decreases from $28.74/m3 to $1.66/m3 (92% reduction), approaching costs typical of seawater desalination despite treating water with triple the salinity. Equipment-level analysis reveals that compression systems dominate capital costs (72–79%) in conventional CHD configurations. LNG cold energy integration eliminates 21,282 kW of refrigeration compression, reducing total compression power by 99.6%. This work provides the first comprehensive techno-economic assessment of produced-water desalination using HFC-152a, establishing a realistic cost basis for commercialization. The findings demonstrate that integrating CHD with existing LNG regasification facilities can dramatically reduce the energy demand and operating costs, positioning hydrate-based desalination as a scalable and economically competitive alternative to conventional technologies.

Coagulation is widely regarded as an indispensable pretreatment process in reverse osmosis (RO) systems of zero liquid discharge applications. Yet in practical applications, coagulation pretreatment often causes perplexing impact on membrane fouling and even deteriorates the RO performance with ambiguous mechanisms, thereby seriously disrupting the progress of RO-based applications. This study systematically reveals the RO performance devolution caused by Fe- or Al-based coagulation pretreatment, and elucidates the fundamental mechanism of membrane fouling deterioration due to residual coagulants. The Al-based coagulation predominantly triggers inorganic fouling, with the disruption of microbial ecological interaction networks within the biofilm exacerbated by copper-induced oxidative stresses. The Fe residues dramatically enhance the production of extracellular polymeric substances and facilitate robust fouling layer development, exacerbating membrane fouling and diminishing RO performance. These findings not only provide essential engineering guidance for optimizing practical operations but also deepen the understanding of the coagulation-RO interactions, establishing a refined framework for enhancing the efficiency and sustainability of advanced water treatment systems.

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.

Improving the Performance of the Solar Panel Reverse Osmosis System Through the Return Water

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.

Reverse osmosis (RO) is one of the most widely used technologies for achieving safe water reuse and can be effectively applied in wastewater recovery for crop irrigation. This paper presents the results of research involving the use of a two-stage RO system connected in series to produce water for agricultural use. A critical factor in applying this technology was achieving the target boron concentration. The effectiveness of the technology is also discussed with respect to the heavy metal content of the permeate. Pre-treatment steps, such as pre-filtration, deironing, and ultrafiltration (UF), are employed to remove colloidal particles and reduce membrane fouling, thereby enhancing longevity. Previous studies have shown that a two-stage reverse osmosis (RO-RO) system for geothermal water desalination (with initial mineralization of 2.5 g/L) produces permeate with a mineralization of 0.094 g/L and permissible heavy metal concentrations that do not adversely affect the quality or safety of irrigation water. Furthermore, due to the permeate’s physicochemical composition, treated geothermal water can be used for drip irrigation without the risk of clogging installations. Future innovations should focus on energy-efficient membrane materials and real-time monitoring to further optimize the desalination process, ensuring sustainable agricultural reuse without soil or crop contamination.

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.

Do membrane transport properties vary under dynamic and cyclic RO? Evidence for constant permeability and hysteresis from channel history

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.