Search Results (94)

Desalination plays a critical role in addressing global water scarcity, yet brine disposal remains a significant environmental challenge. This study evaluates a minimal liquid discharge (MLD) membrane-based system integrating high-pressure reverse osmosis (HPRO) and membrane distillation (MD) for brine treatment, with a focus on the Eastern Mediterranean. A techno-economic assessment (TEA) was conducted to analyze the system’s feasibility, water recovery performance, energy consumption, and cost-effectiveness. The results indicate that the hybrid HPRO-MD system achieves a high water recovery rate of 78.65%, with 39.65 m³/day recovered from MD and 39 m³/day from HPRO. The specific energy consumption is 23.2 kWh/m³, with MD accounting for 89% of the demand. The system’s cost is USD 0.99/m³, generating daily revenues of USD 228 in Cyprus and USD 157 in Greece. Compared to conventional brine disposal methods, MLD proves more cost-effective, particularly when considering evaporation ponds. While MLD offers a sustainable alternative for brine management, challenges remain regarding energy consumption and the disposal of concentrated waste streams. Future research should focus on renewable energy integration, advanced membrane technologies, and resource recovery through brine mining. The findings highlight the HPRO-MD MLD system as a promising approach for sustainable desalination and circular water resource management. Full article

This study develops an integrated environmental–economic assessment framework to evaluate the life cycle environmental impacts and economic costs of CO₂ geological storage and produced water treatment in saline formations in China. Using a case study of a saline aquifer carbon storage project in the Ordos Basin, eight full-chain carbon capture, utilization, and storage (CCUS) scenarios were analyzed. The results indicate that environmental and cost performance are primarily influenced by technology choices across carbon capture, transport, and storage stages. The scenario employing potassium carbonate-based capture, pipeline transport, and brine reinjection after a reverse osmosis treatment (S5) achieved the most balanced outcome. Breakeven analyses under three carbon price projection models revealed that carbon price trajectories critically affect project viability, with a steadily rising carbon price enabling earlier profitability. By decoupling CCUS from power systems and focusing on unit CO₂ removal, this study provides a transparent and transferable framework to support cross-sectoral deployment. The findings offer valuable insights for policymakers aiming to design effective CCUS support mechanisms under future carbon neutrality targets. Full article

The development of efficient and sustainable water recycling systems is essential for long-term human missions and the establishment of space habitats on the Moon, Mars, and beyond. Humidity condensate (HC) is a low-strength wastewater that is currently recycled on the International Space Station (ISS). The main contaminants in HC are primarily low-molecular-weight organics and ammonia. This has caused operational issues due to microbial growth in the Water Process Assembly (WPA) storage tank as well as failure of downstream systems. In addition, treatment of this wastewater primarily uses adsorptive and exchange media, which must be continually resupplied and represent a significant life-cycle cost. This study demonstrates the integration of a membrane-aerated biological reactor (MABR) for pretreatment and storage of HC, followed by brackish water reverse osmosis (BWRO). Two system configurations were tested: (1) periodic MABR fluid was sent to batch RO operating at 90% water recovery with the RO concentrate sent to a separate waste tank; and (2) periodic MABR fluid was sent to batch RO operating at 90% recovery with the RO concentrate returned to the MABR (accumulating salinity in the MABR). With an external recycle tank (configuration 2), the system produced 2160 L (i.e., 1080 crew-days) of near potable water (dissolved organic carbon (DOC) < 10 mg/L, total nitrogen (TN) < 12 mg/L, total dissolved solids (TDS) < 30 mg/L) with a single membrane (weight of 260 g). When the MABR was used as the RO recycle tank (configuration 1), 1100 L of permeate could be produced on a single membrane; RO permeate quality was slightly better but generally similar to the first configuration even though no brine was wasted during the run. The results suggest that this hybrid system has the potential to significantly enhance the self-sufficiency of space habitats, supporting sustainable extraterrestrial human habitation, as well as reducing current operational problems on the ISS. These systems may also apply to extreme locations such as remote/isolated terrestrial locations, especially in arid and semi-arid regions. Full article

The precipitation process of rare earth from a rare earth chloride solution using magnesium bicarbonate yields a dilute magnesium chloride (MgCl₂) solution. The dilute MgCl₂ solution can only be concentrated to a maximum concentration of about 70 g/L by conventional reverse osmosis (RO), which is insufficient for recycling. Low-salt-rejection reverse osmosis (LSRRO) allows for a higher concentration of brine while operating at moderate pressures. However, research on LSRRO for the concentration of MgCl₂ solution is still at an initial stage. In this study, polyamide RO membranes were treated with sodium hypochlorite (NaClO) to prepare low-salt-rejection membranes. The effects of NaClO concentration, pH, and chlorination time on the membrane properties were investigated. Under alkaline chlorination conditions, the membrane’s salt rejection decreased, and water flux increased with increasing NaClO concentration and chlorination time. This can be explained by the hydrolysis of polyamide in the alkaline solution to form carboxylic acids and amines, resulting in a decrease in the crosslinking degree of polyamide. The low-salt-rejection membrane was prepared by exposing it to a NaClO solution at a concentration of 15 g/L and a pH of 11 for 3 h, and the salt rejection of MgCl₂ was 50.7%. The MgCl₂ solution with a concentration of 20 g/L was concentrated using multi-stage LSRRO at the pressure of 5 MPa. The concentration of the concentrated brine reached 120 g/L, which is 87% higher than the theoretical maximum concentration of 64 g/L for conventional RO at the pressure of 5 MPa. The specific energy consumption (SEC) was 4.17 kWh/m³, which decreased by about 80% compared to that of mechanical vapor recompression (MVR). This provides an alternative route for the efficient concentration of a diluted MgCl₂ solution with lower energy consumption. Full article

The growing scarcity of freshwater has accelerated the global deployment of desalination technologies, especially reverse osmosis (RO), as an alternative to meet increasing water demands. However, this process generates substantial quantities of brine—a hypersaline waste stream that can severely impact marine ecosystems if improperly managed. This perspective review explores the use of urease-driven Microbially Induced Carbonate Precipitation (MICP) as a biotechnological solution aligned with circular economy principles for the treatment and valorization of RO brines. Through the enzymatic activity of ureolytic microorganisms, MICP promotes the precipitation of calcium carbonate and other mineral phases, enabling the recovery of valuable elements and reducing environmental burdens. Beyond mineral capture, MICP shows promise in the stabilization of toxic metals and potential integration with microbial electrochemical systems for energy applications. This review summarizes current developments, identifies existing challenges, such as microbial performance in saline conditions and reliance on conventional urea sources, and proposes future directions focused on strain optimization, nutrient recycling, and process scalability for sustainable implementation. Full article

A membrane system was applied for ultrapure water production from the treatment of saline effluent from the canned food industry. The industrial effluent presented a high saline concentration, including sodium chloride, calcium carbonate, calcium sulfates, and magnesium. The effluent was treated using a system of reverse osmosis (RO) and a post-treatment process consisting of ion exchange resins (IEXRs). The RO was accompanied by the addition of a hexametaphosphate dose (2, 6, and 10 mg/L) as an antiscalant to avoid the RO membrane scaling by minerals. In turn, IEXRs were used for water deionization to produce ultrapure water with a reduced concentration of monovalent ions. The antiscalant dose was 6 mg/L, producing clean water from RO permeates with an efficiency of 65–70%. The brine from RO was projected for its reuse in food industry processes. The clean water quality from RO showed 20% total dissolved solids (TDS) removal (equivalent to salts). The antiscalant inhibited the formation of calcium salt incrustation > 200 mg/L, showing low fouling. In turn, anionic resins removed 99.8% of chloride ions, whereas the monovalent salts were removed by a mix of cationic–anionic resin, producing ultrapure water with electrical conductivity < 3.3 µS/cm. The cost of ultrapure water production was 2.62 USD/m³. Full article

The growing demand for sustainable water management solutions has prompted the development of membrane brine concentration (MBC) technologies, particularly in the context of desalination and minimum liquid discharge (MLD) applications. This study presents a simple model of high-pressure nanofiltration (HPNF) for MBC. The model integrates reverse osmosis (RO) transport equations with mass balance equations, thereby enabling acceptable predictions of water flux and total dissolved solids (TDS) concentration. Considering the limitations of the pilot plant data, the model showed reasonable accuracy in predicting flux and TDS, with R² values above 0.99. The simulation results demonstrated that an increase in feed flow rate improves flux but raises specific energy consumption (SEC) and reduces recovery. In contrast, an increase in feed pressure results in an increased recovery and brine concentration. Increasing feed TDS decreases flux, recovery, and final brine TDS and increases SEC. Response surface methodology (RSM) was employed to optimize process performance across multiple criteria, optimizing flux, SEC, recovery, and final brine concentration. The optimal feed flow rate and pressure vary depending on the criteria in the improvement scenarios, underscoring the importance of systematic process improvement. Full article

Sustainable development is linked to the achievement of several different objectives, as outlined by the 17 Sustainable Development Goals (SDGs) defined by the United Nations. Among them are the production of clean water and the combat of climate change, which is strictly linked to the use of fossil fuels as a primary energy source and their related CO₂ emissions. Water and energy are strongly interconnected. For instance, when processing water, energy is needed to pump, treat, heat/cool, and deliver water. Membrane operations for water treatment/desalination contribute to the recovery of purified/fresh water and reducing the environmental impact of waste streams. However, to be sustainable, water recovery must not be energy intensive. In this respect, this contribution aims to illustrate the state of the art and perspectives in desalination by reverse osmosis (RO), discussing the various approaches looking to improve the energy efficiency of this process. In particular, the coupling of RO with other membrane operations, like pressure-retarded osmosis (PRO), reverse electrodialysis (RED), and forward osmosis (FO), as well as the osmotic-assisted reverse osmosis (OARO) system, are reported. Moreover, the possibility of coupling a membrane distillation (MD) unit to an RO one to increase the overall freshwater recovery factor and reduce the brine volumes that are disposed is also discussed. Specific emphasis is placed on the strategies being applied to reduce the MD thermal energy demand, so as to couple the production of the blue gold with the fight against climate change. Full article

Critical mineral recovery from wastewater is an enhancement of conventional mining that can help meet growing demand. This work investigates two energy wastewaters that have previously been shown to be enriched in critical minerals, oil and gas produced water in the Permian Basin and combustion residual leachate. Treatment of these two wastewaters using reverse osmosis or thermal-based methods concentrates critical minerals, which improves the economic viability of critical mineral recovery. Revenue from mineral recovery could also offset treatment costs for operators. This work evaluates the cost of treatment for each wastewater and evaluates the potential revenue from critical minerals concentrated in the brine. The levelized cost of water for combustion residual leachate ranges from USD 1.90 to USD 16.20 (USD 2023/m³ permeate) and for produced water ranges from USD 14.40 to USD 24.30 (USD 2023/m³ distillate). Recovery opportunities range from USD 0.11 to USD 1.13 (USD 2023/m³ permeate) for leachate and from USD 8.28 to USD 42.10 (USD 2023/m³ distillate) for produced water, dominated by the value of magnesium and lithium. Comparing the maximum value of critical minerals contained in produced water and the maximum treatment costs, the value of critical minerals exceeds the cost of treatment by USD 17.80/m³ distillate, which signals a potential revenue opportunity. Full article

As the demand for sustainable water and wastewater management continues to rise in both desalination and industrial sectors, there is been notable progress in developing Zero Liquid Discharge (ZLD) and Minimal Liquid Discharge (MLD) systems. Membrane technologies have become a key component of these systems, providing effective solutions for removing contaminants and enabling the recovery of both water and valuable resources. This article explores recent advancements in the design and operation of ZLD and MLD systems, discussing their benefits, challenges, and how they fit into larger treatment processes. Emphasis is given to membrane-based processes, such as reverse osmosis (RO), membrane distillation (MD), and forward osmosis (FO), as well as hybrid configurations, and innovative membrane materials. These advancements are designed to address critical challenges like fouling, scaling, high energy demands, and high brine production. The article also explores exciting research directions aimed at enhancing the efficiency and durability of membrane technologies in ZLD and MLD systems, paving the way for new innovations in sustainable water management across various industries. Full article

Water scarcity necessitates desalination technologies, yet their high energy demands and brine disposal challenges hinder sustainability. This research study evaluates the energy footprint and carbon emissions of thermal- and membrane-based desalination technologies, alongside Minimal/Zero Liquid Discharge (MLD/ZLD) frameworks, with a focus on renewable energy source (RES) integration. Data revealed stark contrasts: thermal-based technologies like osmotic evaporation (OE) and brine crystallizers (BCr) exhibit energy intensities of 80–100 kWh/m³ and 52–70 kWh/m³, respectively, with coal-powered carbon footprints reaching 72–100 kg CO₂/m³. Membrane-based technologies, such as reverse osmosis (RO) (2–6 kWh/m³) and forward osmosis (FO) (0.8–13 kWh/m³), demonstrate lower emissions (1.8–11.7 kg CO₂/m³ under coal). Transitioning to RES reduces emissions by 90–95%, exemplified by renewable energy-powered RO (0.1–0.3 kg CO₂/m³). However, scalability barriers persist, including high capital costs, RES intermittency, and technological immaturity in emerging systems like osmotically assisted RO (OARO) and membrane distillation (MD). This research highlights RES-driven MLD/ZLD systems as pivotal for aligning desalination with global climate targets, urging innovations in energy storage, material robustness, and circular economy models to secure water resource resilience. Full article

Salinity gradient power (SGP) technologies, including pressure-retarded osmosis (PRO) and reverse electrodialysis (RED), have the potential to be utilized for the purpose of harvesting energy from the difference in salinity between two water streams. One challenge associated with SGP is a reduction in power density due to membrane fouling when impaired water is utilized as a low-salinity water stream. Accordingly, this study sought to explore the feasibility of membrane capacitive deionization (MCDI), a low-energy water treatment technique, as a novel pretreatment method for SGP. Laboratory-scale experiments were conducted to evaluate the impact of MCDI pretreatment on the performance of PRO and RED. The low-salinity water was obtained from a brackish water reverse osmosis (BWRO) plant, while the high-salinity water was a synthetic seawater desalination brine. The removal efficiency of organic and inorganic substances in brackish water reverse osmosis (BWRO) brine by MCDI was estimated, as well as theoretical energy consumption. The results demonstrated that MCDI attained removal efficiencies of up to 88.8% for organic substances and 78.8% for inorganic substances. This resulted in a notable enhancement in the lower density for both PRO and RED. The power density of PRO exhibited a notable enhancement, reaching 3.57 W/m² in comparison to 1.14 W/m² recorded for the BWRO brine. Conversely, the power density of RED increased from 1.47 W/m² to 2.05 W/m². Given that the energy consumption by MCDI is relatively low, it can be surmised that the MCDI pretreatment enhances the overall efficiency of both PRO and RED. However, to fully capitalize on the benefits of MCDI pretreatment, it is recommended that further process optimization be conducted. Full article

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. Full article

Green hydrogen, produced by water electrolysis using renewable energy sources (RES), is an emerging technology that aligns with sustainable development goals and efforts to address climate change. In addition to energy, electrolyzers require ultrapure water to operate. Although seawater is abundant on the Earth, it must be desalinated and further purified to meet the electrolyzer’s feeding water quality requirements. This paper reviews seawater purification processes for electrolysis. Three mature and commercially available desalination technologies (reverse osmosis, multiple-effect distillation, and multi-stage flash) were examined in terms of working principles, performance parameters, produced water quality, footprint, and capital and operating expenditures. Additionally, pretreatment and post-treatment techniques were explored, and the brine management methods were investigated. The findings of this study can help guide the selection and design of water treatment systems for electrolysis. Full article

In this work, reverse osmosis and forward osmosis membranes were prepared using base cellulosic polymers with ZrO₂. The prepared membranes were rolled on the spiral-wound configuration module. The modules were tested on a pilot unit to investigate the efficiency of the RO membrane and the hydraulic pressure effect on both sides of the FO membranes. The RO membrane provided a rejection of 99% for the seawater desalination, and the brine was used as a draw solution for the FO system. First, seawater was used as a draw solution to indicate the best hydraulic pressure, where the best one was 3 bar for the draw solution side, and 2 bar for the feed side, where the water flux reached 48.89 L/m²·h (LMH) with a dilution percentage of 80% and a low salt reverse flux of 0.128 g/m²·h (gMH) after 5 h of operation time. The integrated system of RO and forward-assisted osmosis (PAO) was investigated using river water as a feed and RO brine as a draw solute, where the results of PAO indicate a high-water flux of 68.6 LMH with a dilution of 93.2% and a salt reverse flux of 0.18 gMH. Therefore, using PAO improves the performance of the system. Full article