Seawater Desalination Technology Research Articles

Effect of hollow fiber membrane properties and operating conditions on preventing scale precipitation in seawater desalination with vacuum membrane distillation

Membrane distillation (MD) has attracted attention as a seawater desalination technology because it can treat feed solutions with high osmotic pressures that cannot be treated by reverse osmosis. However, scale precipitation is one of the most significant challenges of MD seawater desalination because it can decrease the vapor permeability and hydrophobicity of MD membranes. Here, the impact of various Reynolds numbers of the feed stream on scaling was investigated. Vacuum MD (VMD) operations with superhydrophobic polyvinylidene fluoride hollow fiber (HF) membranes were performed using seawater at various linear velocities as a feed. Two types of HF membranes with different inner diameters were used. Following 24-h VMD, the amount of scale precipitation on the bore surface of the membrane decreased satisfactorily at a Reynolds number above 1200 due to the decrease in concentration polarization at the bulk/membrane interface. The vapor flux also increased with the Reynolds number. Membranes with larger inner diameters could reduce the amount of scale precipitation and pressure drop, even at the same linear velocity. Thus, it is important for stable VMD seawater desalination to operate at a Reynolds number above 1200 with an HF membrane of large inner diameter.

Coffee Grounds-Doped Alginate Porous Materials for Efficient Solar Steam Generation.

Solar steam generation (SSG) devices have emerged as one of the promising technologies for seawater desalination to meet the worldwide demand for clean water. Herein, we fabricated a new monolithic SSG system derived from waste coffee grounds (CG) through a simple carbonization followed by a freeze-drying process (named as CCGA). The as-prepared CCGA possesses a porous structure with superhydrophilic, abundant porosity (81.7%); low thermal conductivity (0.129 W m-1 K-1) in a wet state; low apparent density (25 mg cm-3); and broad sunlight absorption in a wet state (ca. 93%). The combination of its carbon nature and abundant porous structure endowed barrier-free water transmission channels, a self-floating property, and a superb photothermal conversion performance to the SSG. The temperature of the CCGA's upper surface can reach up to 42.6 °C under 1 sun irradiation, and for pure water, the evaporation rate of CCGA can be up to 1.486 kg m-2 h-1, corresponding to a good photothermal conversion efficiency of 86.96%. It also exhibits an excellent desalination capability; e.g., the photothermal conversion efficiency of CCGA in NaCl (20 wt %) brine is measured to be 75.77% under 1 sun irradiation, and the fresh water obtained from artificial seawater can achieve the WHO's standard for domestic water. With the advantages of low cost and a simple preparation process, such biomass-based CCGA materials may have great potential as an efficient SSG device for seawater desalination.

Hollow SiO2 microspheres in-situ doped poly(ionicliquid)s gels as efficient solar steam generators for desalination

AbstractSolar steam generation (SSG) is one of the promising technologies for seawater desalination and contaminated water purification. However, SSG devices are always restricted by poor insulation performance, insufficient solar spectrum absorption and serious salt-fouling. Here, a double-layered novel SSG system was fabricated by using poly(ionicliquid)s gels with hollow SiO2 microspheres in-situ doping to enhance the thermal insulation of lower layer, and co-modified the top surface by polypyrrole (PPy) and silver particles to strengthen the solar absorption capability. Benefiting from the low thermal conductivity (0.082 W m−1 k−1), strong light absorption (ca. 96%) and adequate water transport capability of poly(ionic liquid)s gels. As SSG device, a superb photothermal conversion efficiency of 90.5% is achieved under 1 sun illumination. Moreover, the poly(ionic liquid)s gels based SSG system also shows good desalination performance in artificial sea water and high concentration brine, and the purified water from artificial seawater can achieve the WHO's standard for drinking water. Therefore, this work combined attractive in-situ doping and co-modified strategies for fabricating high performance and thus shows significant potential for real applications.

A water-heat combined supply system based on waste heat from a coastal nuclear power plant in northern China

• A new water-heat combined supply system based on waste heat is proposed. • The system realizes the simultaneous delivery of water and heat. • The heating and water supply costs are 34.27 ¥/GJ and 4.08 ¥/m 3 , respectively. • The system has a higher exergy efficiency and a better economic benefit. Based on the existing waste heat recovery technology and seawater desalination technology, a water-heat combined supply system based on waste heat from a costal nuclear power plant is proposed. The proposed system can improve the heating capacity of district heating systems and reduce the energy consumption of water-generating seawater reverse osmosis systems by recovering the waste heat from exhaust steam in a nuclear power plant. Through the simultaneous delivery of water and heat, the long-distance conveyance cost is reduced. The thermodynamic characteristics, energy-saving properties, environmental benefits, and economic efficiency of the proposed system are discussed and analysed. The results show that the heating capacity of the proposed system is increased by 55.5% compared to the original extraction steam heating load. The exergy efficiency is 16.07% higher and the heating cost is 12.32 ¥/GJ lower than those of traditional cogeneration district heating systems. The water supply cost of the proposed system is 2.95 ¥/m 3 lower than that of the conventional desalination water supply system. The current results of this study will be helpful in solving problems related to heat and water resource shortages and the high costs of long-distance heat and water conveyance in coastal areas.

Seawater battery desalination with a reverse osmosis membrane for simultaneous brine treatment and energy storage

As it is typically disposed of to the ocean, naturally produced brine water has been an avoidable issue in seawater desalination technology, particularly in the reverse osmosis (RO) process. To address this issue, a seawater battery-desalination (SWB-D) system was used to reduce the concentration of RO brine while also storing electrical energy by harvesting sodium ions from the brine. The SWB equipped with an anion exchange membrane (AEM) can lower the RO brine concentration to seawater levels, but the use of AEM for brine treatment is costly and the slow kinetics of salt transport require long operation times. In this study, we present a proof of concept for using RO membrane as an alternative to AEM in the SWB desalination system. Owing to its low cost and unexpected support for salt removal via diffusion across the RO membrane, using RO membrane is a viable application. The effect of diffusion enables SWB-D with RO membrane to reduce the charging time by 36.8% (up to ∼40.5% salt removal) compared with SWB-D with AEM. In addition, ∼52.5 kWh m−3 of energy (assuming 80% energy recovery) was saved while lowering the concentration of brine to seawater levels (from 1.2 to ∼0.6 M).

Renewable Solar Energy Coupled to a Brackish Water Desalination Plant: Efficiency and Optimization

In order to reduce fossil energy consumption at desalination plants, it has become necessary to replace fossil energy with clean energy. Currently, the reverse osmosis systems connected to solar energy is a promising technology for desalination of seawater / brackish water, especially in arid and semi-arid areas that have a large solar deposit and are remote from the public grid. The objective of this work is to show the efficiency of introducing renewable energy in brackish water desalination plants by the effect of comparing the energy consumption for a system without renewable energy source and system powered by the photovoltaic system (solar energy). As well as a program developed on Matlab software environment in order to, optimize the energy consumption of a desalination plant for the proposed plant is about 0.1269 kWh/m3.

Valuing improved water services and negative environmental externalities from seawater desalination technology: A choice experiment from the Galápagos

While seawater desalination technologies can improve drinking water supply, they can also generate significant environmental externalities. A choice experiment was implemented to investigate household preferences for potential trade-offs between improved water services and environmental impacts from seawater desalination in the Galápagos Islands. Our results indicate that households are willing to pay for water quality improvements, and for protection of coastal ecosystems and marine organisms. In contrast, households seem indifferent regarding water availability and potential impacts on air quality. Our findings also suggest that respondents who consistently reject the proposed desalination project tend to be less affluent and have stronger environmental preferences than those who support it. It is concluded that stated-preference studies on improved water services should also elicit preferences for potential environmental effects of the proposed water technology.

Carbon black and polydopamine modified non-woven fabric enabling efficient solar steam generation towards seawater desalination and wastewater purification

• PDA/CB composite non-woven PP fabric was prepared for solar energy harvesting. • Hierarchical structure and synergetic effects of CB/PDA contributed to high light absorbance. • The evaporation rate of 1.68 kg m -2 h −1 with a solar steam efficiency of 91.5% was achieved. • The solar evaporator demonstrated superior salt resistance and ability to purify seawater and various wastewaters with high efficiency. The utilization of solar energy for steam generation is a highly efficient and sustainable technology for seawater desalination to solve the long-standing water crisis. Carbon-based materials have shown promising thermal-heat conversion efficiency due to their broadband solar absorption. Herein, carbon black (CB) was combined with polydopamine (PDA) to develop a high-performance, low-cost, and scalable PDA/CB@PP composite non-woven fabric was fabricated by dip-coating of CB and in situ polymerization of PDA. The hierarchical structure constructed on the fiber surface and the synergetic effects of CB and PDA contributed to the high light absorbance (>95%), superhydrophilicity, and high energy conversion efficiency. The one-way fluidic PDA/CB@PP photothermal based solar steam evaporator demonstrated a high evaporation rate of 1.68 kg m -2 h −1 with a solar steam efficiency of 91.5%. Moreover, the PDA/CB@PP fabric shows remarkable salt resistance when purifying seawater because of the water channel preserved by the hydrophilic porous structure of the fabric which could provide sustained water supply. Besides, the PDA/CB@PP fabric possesses excellent purification capability to wastewaters contaminated by heavy-metal and chemical dyes. This study provides insights into the design and development of low-cost, scalable, highly stable, and efficient solar steam generators for seawater desalination and wastewater purification.

Pilot testing of a novel integrated Multi Effect Distillation - Absorber compressor (MED-AB) technology for high performance seawater desalination

This work presents a novel integration of Multi Effect Distillation with Absorption compressor (MED-AB) to reduce the energy consumption and unit water cost. The MED-AB pilot plant has been installed with a nominal capacity of 25 m3/day to validate the concept under a seawater salinity of 57,500 ppm (West of Qatar). Both pilot testing and the simulation results confirm the features of the novel design of the MED-AB process. Simulation of a commercial evaporator of 15 MIGD capacity showed that the specific energy consumption of the proposed MED-AB is calculated as 4.8 kWh/m3, which is 60% lower than the existing MED-TVC plant (13 kWh/m3). Compared to the traditional MED-TVC, the seawater feed and pumping power of MED-AB process is lower by 70% and 55%, respectively. The results confirm the minimization of the environmental impact of dumping thermal energy back into the sea and reduce the plant's capital investment, covering feed pumps size and the intake/outfall civil work. The levelized unit water cost of the MED-AB is calculated as 0.46 $/m3, which is 22% lower than that of a conventional MED-TVC desalination plant. The novel MED-AB technology would create a potential solution for the industrial applications of high salinity byproduct and solar desalination.

Renewable Water Harvesting by Amyloid Aerogels and Sun

AbstractSolar distillation is an appealing and facile technology for seawater desalination and water purification, but constructing stable, environmentally‐friendly, and cost‐effective solar evaporators often remain unfeasible. Here, amyloid hybrid aerogels are introduced for universal and renewable freshwater production by relying on the combination of sustainable materials and solar energy, thus making the process highly ecological and virtually costless. Amyloid fibrils obtained from whey, a byproduct of the dairy industry, are used as the main scaffold for the aerogels, whose solar energy harvesting properties of the top surface are enhanced by bioinspired dark polymers, such as polydopamine. Due to the fast water transport throughout the porous aerogels, the high‐yielding photothermal conversion ability of the top surface, and efficient heat insulation at the bottom, the hybrid amyloid fibrils aerogel exhibits a water evaporation rate of 1.61 kg·m−2 h−1 with a solar‐thermal conversion efficiency as high as 91.3% under 1 sun illumination. The process allows desalinating various seawater sources with different salinities to levels below the drinking water threshold recommended by the World Health Organization. Moreover, the same hybrid amyloid evaporator is highly efficient in removing heavy metals, organic pollutants, bacteria, and viruses from water, introducing a general, sustainable and energy‐efficient solution for desalination and water purification.

Performance of MXene incorporated MOF-derived carbon electrode on deionization of uranium(VI)

As the key element in the nuclear industry, uranium (U) has been widely concerned for its stable acquisition and efficient recycling. Capacitive deionization (CDI), which known as a seawater desalination technology, has shown great potential for uranium-adsorption. However, the poor selectivity restricts the application of CDI in uranium extraction. In this work, a carbonized MIP-202/MXene (CMM) composite was developed for highly efficient selective electrosorption of U(VI) from multi-ionic water. The uniformly decorated MIP-202 can prevent MXene from aggregation and provide rich pore structures, large specific surface area and additional nitrogen source for the efficient electrosorption of U(VI). With the addition of MXene nanosheets, a conductive network was introduced into the CMM and improved mechanical robustness of material to facilitate rapid charge transfer at the interface. As a result, the CMM electrode exhibited a maximum adsorption capacity of 582.46 mg g−1 calculated from Langmuir model and a removal ratio of 89.1% at 1.2 V in UO22+ solution. The selectivity adsorption of CMM for UO22+ can reach 92.3% when treated with multi-ionic solution. Besides, there is an interesting fact that the decreased ratio of added MXene can got a higher adsorption capacity, which may cause by the two composite structures formed when the mixing ratio changed. Overall, the excellent conductivity, high adsorption capacity and selectivity make CMM a promising electrode in CDI for efficient extraction of uranium from water.

Pilot testing of a novel Multi Effect Distillation (MED) technology for seawater desalination

This work presents an improved evaporator design of the Multi Effect Distillation (MED) to minimize the thermal losses and footprint of the evaporator. An advanced modular MED pilot plant has been installed with a nominal capacity of 25 m3/day to validate the concept under a seawater salinity of 57,500 ppm (Dukhan Coast, West of Qatar), at the top brine temperature of 65 °C. Both the pilot testing and the simulation results confirm the features of the novel design of the MED. By implementing this invention's design, the heat transfer area has been decreased and accordingly, the capital cost of the evaporator is reduced by 20%. The tube arrangement with new vapor route allows the removal of the traditional demister, which accordingly reduces the footprint of the desalination plant by 65%. The sieve tray for spraying the seawater over the rectangular and inline tube bundle creates a uniform wettability. The improved design also discloses the utilization of an online vent water-ejector, for vent out of the non-condensable gases (NCGs). The novel evaporator design based low temperature MED technology, shows a potential solution for the industrial applications of high salinity byproduct and solar desalination.

Energetic performance analysis on a membrane distillation integrated with low concentrating PV/T hybrid system

Membrane distillation seawater desalination technology has received widespread attention. However, this technology has problems such as high energy consumption and high initial temperature requirements. A membrane distillation seawater desalination system integrated with low-concentrating photovoltaic/thermal (LCPV/T-MD) modules was designed. With the help of concentrating photovoltaic panels and solar collectors, the working fluid required for membrane distillation is cascaded heating to obtain distilled fresh water. The integrated LCPV/T-MD mathematical model the hybrid experimental system were established, and the thermal, electrical performance, and water yield were analyzed. The results show that the greater ΔP, the lower of the salinity c, and the higher the inlet water temperature Tin, the greater the water yield. The LCPV/T-STC heating subsystem can heat the water temperature above 60 °C, and then auxiliary heating by heating rod can meet the requirements of MD system for inlet water temperature. In the experiment, the thermal efficiency and the electrical efficiency of the system can reach 56.2% and 15.9%, respectively. The GOR of the total LCPV/T-MD system can reach 0.69, and the MD subsystem water yield can reach 0.579 L/(h·m2). The findings can provide guidance for the further study of membrane distillation.

Solar-Powered Sustainable Water Production: State-of-the-Art Technologies for Sunlight-Energy-Water Nexus.

Alternative water resources (seawater, brackish water, atmospheric water, sewage, etc.) can be converted into clean freshwater via high-efficiency, energy-saving, and cost-effective methods to cope with the global water crisis. Herein, we provide a comprehensive and systematic overview of various solar-powered technologies for alternative water utilization (i.e., "sunlight-energy-water nexus"), including solar-thermal interface desalination (STID), solar-thermal membrane desalination (STMD), solar-driven electrochemical desalination (SED), and solar-thermal atmospheric water harvesting (ST-AWH). Three strategies have been proposed for improving the evaporation rate of STID systems above the theoretical limit and designing all-weather or all-day operating STID systems by analyzing the energy transfer of the evaporation and condensation processes caused by solar-thermal conversion. This review also introduces the fundamental principles and current research hotspots of two other solar-driven seawater or brackish water desalination technologies (STMD and SED) in detail. In addition, we also cover ST-AWH and other solar-powered technologies in terms of technology design, materials evolution, device assembly, etc. Finally, we summarize the content of this comprehensive review and discuss the challenges and future outlook of different types of solar-powered alternative water utilization technologies.

Facile Preparation of a Carbon-Based Hybrid Film for Efficient Solar-Driven Interfacial Water Evaporation.

Solar-driven interfacial water evaporation is one promising technology for seawater desalination and sewage purification because it offers a feasible and sustainable strategy to relieve global water scarcity. Herein, a novel hybrid film composed of recycled carbon soot and poly(vinyl alcohol) is developed by a very simple, green, and highly scalable "salt-assisted" assembling method. The hybrid film possesses characteristics with a porous structure, superhydrophilicity, ∼100% light absorption, and low thermal conductivity, which can effectively convert light into heat under solar illumination. Consequently, the hybrid film can achieve a photothermal conversion efficiency of 91.5% under a stimulated solar irradiation of 1 kW m-2. Furthermore, the hybrid film can be applied for seawater desalination and dye wastewater purification. The findings of our work not only provide a new photothermal platform with high light-to-thermal conversion ability and good reusability but also open a new avenue for the applications of carbon soot-based hybrid films in solar-assisted water evaporation and sewage purification.

Recent Desalination Technologies by Hybridization and Integration with Reverse Osmosis: A Review

Reverse osmosis is the leading technology for desalination of brackish water and seawater, important for solving the growing problems of fresh water supply. Thermal technologies such as multi-effect distillation and multi-stage flash distillation still comprise an important portion of the world’s desalination capacity. They consume substantial amounts of energy, generally obtained from fossil fuels, due to their low efficiency. Hybridization is a strategy that seeks to reduce the weaknesses and enhance the advantages of each element that makes it up. This paper introduces a review of the most recent publications on hybridizations between reverse osmosis and thermal desalination technologies, as well as their integration with renewable energies as a requirement to decarbonize desalination processes. Different configurations provide improvements in key elements of the system to reduce energy consumption, brine production, and contamination, while improving product quality and production rate. A combination of renewable sources and use of energy and water storage systems allow for improving the reliability of hybrid systems.

Reproductive toxicity and metabolic perturbations in male rats exposed to boron

The poor rejection of boron (B) by reverse osmosis, a dominant seawater desalination and household-scale water treatment technology, is a critical issue given its potential adverse effects on human health and the extensive and increasing application of seawater desalination facilities worldwide. Although previous in vivo studies have revealed the reproductive toxicity of B, the mechanistic underpinnings and changes in the global metabolome remains undefined. To systematically investigate the effects of B on male reproduction and endogenous metabolic fingerprints, adult male rats were exposed to different doses of borax (25, 50 and 100 mg B/kg/day) for 28 days via oral gavage. After mating the treated rats with untreated female rats, we found a significant reduction in the proportion of live foetuses only in the highest dose group (100 mg B/kg/day) compared with the control group (treated with deionised water). Furthermore, compared with the control group, the concentration of plasma follicle-stimulating hormone increased and the activities of testicular enzymes (malate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase) were significantly upregulated in the 100 mg B/kg/day group, whereas the activity of testicular sorbitol dehydrogenase and the concentrations of plasma interleukin-5 were inversely proportional to the doses and were the lowest at the highest dose of 100 mg B/kg/day. The concentrations of testicular hormones (e.g., oestrone, oestradiol, oestriol, testosterone, cortisol and androstenedione) were significantly upregulated in the rats exposed to 100 mg B/kg/day. Non-targeted metabolomics and lipidomics revealed a significant disruption of lipid and amino acids metabolism at the highest dose, particularly that of linoleic acid, α-linolenic acid, sphingolipid, glycerolipid, glycerophospholipid, branched-chain amino acid and nicotinate metabolism, and unsaturated fatty acids synthesis, which are predominantly associated with inflammation, antioxidation defence, energy utilisation, steroid hormone synthesis and lipid abnormalities. Our results offer insights into the mechanisms underlying the adverse effects of B on reproduction and into the health risks posed by drinking desalinated seawater that containing elevated B concentrations.

Design and Energy Consumption Analysis of Small Reverse Osmosis Seawater Desalination Equipment

The reverse osmosis method has developed extremely rapidly in recent years and has become the most competitive seawater desalination technology in the world, and it has been widely used in all aspects. Large-scale reverse osmosis desalination plants cannot provide fresh water resources in areas with insufficient water resources and limited space. Therefore, this paper proposes a research plan for a small seawater desalination device based on reverse osmosis, which is mainly suitable for handling emergencies, disaster relief, desert areas and outdoor activities and other needs for timely freshwater resources. It mainly includes pretreatment modules, a reaction infiltration module, a post-processing module and an energy supply module. Detailed design calculations are carried out for the small-scale reverse osmosis membrane system, including the selection and quantity and arrangement of membranes. Subsequently, the one-stage two-stage small-scale reverse osmosis membrane system was modeled, and its energy consumption was analyzed theoretically from the perspectives of specific energy consumption and energy utilization efficiency; the main influencing factors were clarified, and the optimal recovery rate for system operation was determined to be 20%–30%. Finally, an experimental prototype was built to conduct relevant experiments to determine the influence trend of pressure, temperature, concentration, and flow rate on the operating performance of the reverse osmosis system.

Understanding impacts of flow rate on performance of desalination flow batteries

It is critical to develop more efficient and cost-effective desalination technologies capable of fully seawater desalination capacity to meet the grand freshwater scarcity challenge. Desalination flow batteries are an emerging electrochemical device capable of integrated energy storage and desalination and represent a promising electrochemical technology for scalable and cost-effective desalination of seawater. Herein, we report the impacts of flow rate on the performance of a methyl viologen/sodium ferrocyanide (MV/Na4[Fe(CN)6]) desalination flow battery (DSRFB). It was found that the increase of the flow rate can lower the battery resistance and improve energy efficiencies, power density, and desalination efficiency. Specifically, increasing the flow rate from 20 to 60 mL/min with an increment of 20 mL/min, the MV/Na4[Fe(CN)6] DSRFB manifested an increase of energy efficiency from 56% to 64%, and an increase of power density from 14.72 to 15.33 mW/cm2. More importantly, the desalination percentage of the DSRFB was increased from 86.9% at 20 mL/min to 93.9% at 60 mL/min.

A review of resource recovery from seawater desalination brine

In order to address freshwater scarcity, seawater desalination technologies have been widely studied in recent years. However, the disposal of desalination brine which contains an even higher concentration of salts than seawater can potentially damage the surrounding environment. Therefore, alternative approaches aiming to recover valuable resources from desalination brine have been conducted. Three resources that can be recovered have been studied in this paper, which are minerals, freshwater and energy. The techniques to recover minerals can be divided into pressure-driven techniques, thermal-driven techniques, electro-driven techniques and other techniques. The water recovery techniques employ mainly membrane/thermal integrated hybrid processes, while the energy recovery techniques such as pressure retarded osmosis (PRO) and reverse electrodialysis (RED) utilize the salinity gradient energy (SGE) to generate energy. The valuable mineral products have also been reviewed in this paper in terms of recovery methods, performance of processes and product quality. The reviewed products are sodium salts (NaCl, NaOH, Na2SO4), lithium salts (LiCl, Li2CO3), magnesium salts (struvite, Mg(OH)2, MgSO4, MgO), calcium salts (CaSO4, CaCO3) and other minerals (U, Rb, Cs). Based on the cost and revenues of each technique, an economic comparison has been conducted along with the cost analysis of operating desalination plants.