Technology For Water Production Research Articles

Synergistic effects of hydrophilic function group and micropores on water evaporation in a novel carbon hydrogels for efficient solar steam generation

Solar steam generation (SSG) using hydrogels is emerging as a promising technology for clean water production. Herein, a novel oxygen-doped microporous carbon hydrogel (OPCH), rich in hydrophilic groups and micropores, has been synthesized from microalgae to optimize SSG. OPCH outperforms hydrogels with hydrophobic porous carbon or nonporous hydrophilic biochar, significantly reducing water's evaporation enthalpy from 2216.06 to 1107.88 J g−1 and activating 42.3 g of water per 100 g for evaporation, resulting in an impressive evaporation rate of 2.44 kg m−2 h−1 under one sun. A detailed investigation into the synergistic effects of hydrophilic groups and micropores on evaporation via a second derivative thermogravimetry method revealed two types of bonded water contributing to enthalpy reduction. Molecular dynamics simulations provided further insights, revealing that the hydrophilic micropores considerably decrease both the number and the lifetime of hydrogen bonds among water molecules. This dual effect not only reduces the energy barrier for evaporation but also enhances the kinetic energy needed for the phase transition, significantly boosting the water evaporation process. The sustained high evaporation rates of OPCH, observed across multiple cycles and under varying salinity conditions, underscore its potential as a highly efficient and sustainable solution for SSG applications.

Enhancing the photothermal efficiency of MoS2 through ultraviolet-ozone exposure for improved solar evaporation

MoS2 has been explored as a photothermal layer for solar-driven water evaporators to produce clean water. However, there have been no reports studying the effects of ultraviolet-ozone (UVO) exposure on the photothermal properties of MoS2. This study investigates the impact of UVO exposure (10, 20, and 30 minutes) on bulk 2H-MoS2 synthesized via a hydrothermal method at 200°C for 16 hours. The freshly prepared MoS2 contained high concentrations of molybdenum oxide phases, which significantly diminished after 10 minutes of UVO exposure, indicating improved purity of MoS2. The increased purity of UVO-exposed MoS2 led to a rise in layer temperature to 47.37°C, surpassing the 43.40°C temperature of MoS2 without UVO exposure. Extending the UVO exposure to 30 minutes further increased the number of surface edge sites, thereby enhancing the wettability of MoS2 due to the increased binding sites for polar water molecules. Consequently, MoS2 exposed to UVO for 30 minutes demonstrated the highest evaporation rate of 1.83 kg m−2 h−1, achieving a photothermal efficiency of 94%, a high salt rejection rate of 99.98%, and a high heavy metal ion rejection rate of 91.84%. Therefore, the application of UVO-exposed MoS2 serves as an effective photothermal layer for sustainable and eco-friendly clean water production technologies.

Improving the photovoltaic/thermal (PV/T) system by adding the PCM and finned tube heat exchanger

In this study, we aimed to improve the performance of the photovoltaic-thermal (PV/T) system by incorporating phase change material (PCM) into the heat exchanger. A new design for the finned tube heat exchanger layout was introduced, and a comprehensive mathematical model was developed to analyze the heat transfer process and operational efficiency of the PV/T system. The temperature variation of the PV/T system was simulated and validated using real climatic conditions in Baghdad and Tehran. To conduct our analysis, we utilized the OpenFOAM software and enhanced our solver to accurately capture the melting process in the PCM. We also investigated the effects of wind velocity and atmospheric pressure on the performance of the PV/T system. Our findings showed that an increase in wind velocity led to an increase in PV/T efficiency, while an increase in atmospheric pressure resulted in a decrease in efficiency. Additionally, we observed that the Baghdad climate was more sensitive to variations in wind velocity compared to Tehran. In Baghdad and Tehran, the highest obtained water temperatures were 54.3 and 50.1 °C, respectively. Furthermore, a study was conducted to assess the viability of using PV/T (photovoltaic-thermal) technology for hot water production in the Multi-Effect Desalination and Adsorption Desalination cycle. The proposed PV/T system demonstrated an average performance improvement of 26% compared to traditional PV/T systems. During warmer months, the system was capable of producing 0.11 and 0.10 m3/h of potable water per month in Baghdad and Tehran, respectively. Furthermore, the system had the potential to generate 170 and 140 kW h of electricity for the respective cities.

Experimental study on operating characteristics and control strategy of CO2 heat pump in circulating heating mode

The CO2 heat pump is a promising low carbon technology for domestic hot water production due to its potential heating advantages and the natural properties of CO2. However, the change pattern of operational parameters, heating time, and energy efficiency of CO2 heat pump in circulating heating mode remains to be fully revealed. Meanwhile, the matching control strategies to improve the system performance have not been developed. Firstly, we experimentally revealed the operating characteristics of CO2 heat pump in circulating heating mode. Results demonstrated that it is quite challenging to simultaneously maintain the lower input power, shorter heating time, and higher coefficient of performance (COP) without taking control measures. It is found that the circulating heating process could be divided into stable and upward periods, depending on the water temperature at the inlet of gas cooler. The deterioration of the system performance appears during the upward period, where the instantaneous COP drops from 4.1 to 3.1. This is because input power rises, while the heating capacity drops as the water temperature at the inlet of gas cooler increases. Secondly, we experimentally developed a matching control strategy to improve the system performance during the upward period. The control method is the correlation of optimal electronic expansion valve opening, and the regulation frequency is regulating for 1 °C per rise of the water temperature at the inlet of gas cooler. As a result, the overall COP increased by 3.71%, and the overall input power reduced by 3.74% while the heating time remained constant.

MXene/aramid nanofiber films enables highly efficient photothermal conversion for solar-driven water evaporation

Efficient utilization of solar energy is a resultful strategy to solve the problem of shortage of traditional fossil energy. Solar-driven water evaporation is considered as an effective, low-cost, renewable, and environment-friendly technology for clean water production. Herein, a novel MXene/ANF composite film was fabricated by facile vacuum filtration method. Benefiting from the excellent photothermal conversion property of MXene and the flexibility and stability of ANF, the MXene/ANF composite film exhibits high-efficient photothermal conversion and water evaporation ability. The as-prepared MXene/ANF composite film can reach as high as 98.0 °C at the laser power density of 1 kW/m2 and 54.0 °C under the solar power density of 1 kW/m2. Meanwhile, the water evaporation of MXene/ANF composite film can reach 1.432 kg/m2 under the solar power density of 1 kW/m2. Therefore, the MXene/ANF composite films possess a good prospect to be applied as a solar-driven water evaporation device to solve the problem of shortage of traditional fossil energy and inadequate freshwater supply.

Water Management Adaptation to Climate Change in Mediterranean Semiarid Regions by Desalination and Photovoltaic Solar Energy, Spain

Integration of renewable energy sources and water production technologies is a must when facing water scarcity problems in semiarid regions, such as Mediterranean regions. The use of additional water resources and production methods, such as reclaimed water and, more specifically, desalinated water, means present and necessary water resources to introduce in the water balances to attend to water demands within a global warming and droughting scenario. These solutions have the inconvenience of energy/power needs and costs. However, the development of renewable energies like photovoltaic solar energy, with lower and lower costs and greater efficiency, makes these economically feasible facilities, reaching competitive production costs for marine or sea desalinated water by around 50% of reduction in energy costs and 20–30% of savings in final water production cost. This paper presents a practical project or action focused on the integration of renewable energies and new water resources by introducing a Photovoltaic Energy Plant (PVEP) as an energy source to feed a Seawater Desalination Treatment Plant (SWDTP). The PV facility is designed to cover all the energy demanded using the SWDTP during the day, and even studying the possibility of selling the energy production exceeds and injecting them into the energy supply network, covering the needs of buying energy needed during the high period where there is no photovoltaic energy production. Thus, savings related to energy costs and even incomes coming from energy sales mean an important reduction in operation costs or expenditures (OPEX), which makes economically feasible and sustainable the investment and the final price of water produced within the Mutxamel SWDTP. The final reduction cost in water desalination reaches 25% on average.

Role of China's agricultural water policy reforms and production technology heterogeneity on agriculture water usage efficiency and total factor productivity change

Role of China's agricultural water policy reforms and production technology heterogeneity on agriculture water usage efficiency and total factor productivity change

Water Production and Desalination Technologies by Using the Solar Energy and Suggestions for Their Future Applications

Because global water scarcity is expected, the water shortage will occur significantly for the developing countries and vulnerable social group. It is expected that alternative water resource will be required to provide sustainable surface water supply for the areas where water infra-structure such as Dam is limited against the unexpected climate change. Groundwater which is the one of the main water sources for the developing countries is sometimes facing contaminations by heavy metals and salts from geological reason and seawater intrusion, respectively. In order to remove the contaminants, the decentralized and off-grid type ion separation technology is required. In this study, solar-power based water treatment and desalination case studies and theoretical study for solar energy were presented. Moreover, suggestions of water supply methods for developing countries and vulnerable social group were also showed considering the field conditions based on the case studies.

Design optimization of compact gas turbine and steam combined cycles for combined heat and power production in a FPSO system–A case study

This case study aims to cover a wide range of relevant aspects related to combined cycle design, mechanical integrity and operational reliability for cogeneration of heat and power in FPSO systems. The methods consist of combined optimization of combined cycle thermodynamic design and geometry of steam generator; vibration analysis for flow induced vibrations; and thermal stress estimation of casings during cold start-stop scenarios. Challenges and opportunities for reliable water treatment systems are explored. The results show that small tubes, a compact tube bundle and a low condensation temperature reduces the once-trough steam generator (OTSG) weight. The vibrations numerical simulations in this work support the standard recommendations of using 35 times tube OD as upper limit for the unsupported tube length, which could be used as a reasonable design criterion. Thermal stresses analysis indicates that the design of beam arrangement, location, and stiffness of beams has a major impact on thermal stresses, and can be optimized to different plate thicknesses in order to avoid fatigue damage. Focus should be on reducing leaks of deaerator, steam turbine and condenser. It is recommended to add Na sensors after condenser and investigating the use of Electrodeionization (EDI) technology for make-up water production from seawater.

Scalable, Green, and Cost-Effective Carbonized Sand for Efficient Solar Desalination.

Nowadays, sweet and drinkable water shortage is a global issue which has attracted widespread attention. Desalination of seawater as the greatest source of water on our planet using solar energy as the most abundant and green energy source for producing fresh water can help us address this issue. Interfacial solar desalination is a state-of-the-art, sustainable, green, and energy-efficient method that has been studied lately. One of the key parameters for researching this method with reasonable efficiency is a photothermal material. Herein, carbon-coated sand was synthesized using abundant, green, and low-cost materials (sand and sugar), and its performance as a photothermal material is investigated and reported. In this work, a three-dimensional (3D) system is introduced to develop the performance and efficiency of the system under real sun irradiation and natural circumstances. The salt rejection ability of the system is another important thing we should notice due to the high salinity of seawater that we want to desalinate. The superhydrophilic carbonized sand demonstrated a good evaporation rate of 1.53 kg/m2h and 82% efficiency under 1 sun irradiation and upright salt rejection ability, which exhibited its capability to be used in green solar-driven water vaporization technology for sweet water production. The effects of important parameters, including light intensity, wind speed, and environment temperature, on the evaporation rate using carbonized sand as a solar collector in a solar desalination system were studied in both laboratory and real systems.

친환경 Carbon Eating Concrete 제조를 위한 나노버블 이산화탄소 용해 배합수 제조 기술 개발 및 최적화

친환경 Carbon Eating Concrete 제조를 위한 나노버블 이산화탄소 용해 배합수 제조 기술 개발 및 최적화

PROCESS OF DETERMINATION OF SURFACE WATER BY ULTRAVIOLET RADIATIONS

This scientific research work deals with water disinfection in surface water reservoirs. According to the research, work was carried out to eliminate harmful microorganisms, viruses and microbacteria in the water. According to scientific research work, the electronic circuit of the device for capturing UV rays with a wavelength of 220-240 nm was studied. In the same way, the energy and spectral characteristics of the device, the parameters related to current and power are provided. The design and economic efficiency of the UV radiation device was considered and studied experimentally. In the water production technology, the main sanitary requirements for the organization of UV disinfection of water were considered. In the article , a number of provisions of the main documents of water and sanitary legislation regarding the quality of purified water, hygienic requirements, amount of ultraviolet radiation guaranteeing a given degree of disinfection, ultraviolet installations and their location were shown. At the same time, the scheme of the cleaning process, as well as measures to ensure safe working conditions of the personnel servicing the equipment were considered.

Comprehensive performance evaluation of water and power production technologies using water-exergy nexus analysis

Insight into less-known aspects of sustainable development has been deepened through the development of the nexus between water and energy in the last decades. However, the complex sustainability problem cannot be fully investigated owing to the intrinsic shortcomings of the physical concept of energy. This study considered the exergy concept as a substitute for energy to develop water-exergy nexus analysis (WExNa) as an efficient analytical framework. Accordingly, four evaluation criteria were proposed as quantitative tools of WExNa. Consequently, seven power and seven water production technologies were analyzed considering the model uncertainties in their life cycle. A big data bank, comprising 803 water and 812 power production plants, was labeled to facilitate consideration of the spatial, temporal, and environmental variety of technologies in a stochastic data-driven program. The results showed that wind, solar, and concentrating solar power plants used the least amount of water for exergy production during the entire life cycle, whereas only geothermal power technology could compete with non-renewable power in the operating stage by an exergy dissipation for product exergy index in the range of 0.2 – 3. Despite the significance of chemicals in water production, chemical exergy dissipation was negligible compared with electrical and thermal exergies. Water treatment facilities were generally superior to desalination technologies, considering all types of exergy for water. Although multi-stage flash and electrodialysis exhibited the best and worst operation metrics among the water technologies, they dissipated the most and least exergies for water production, respectively, with an acceptable confidence considering the entire life cycle. Moreover, the contrast between conventional operation indexes and the new WExNa variables entails potentially new horizons through the sustainable evaluation of engineering systems using the proposed analysis.

Carbon footprint analysis and carbon neutrality potential of desalination by electrodialysis for different applications

Low-carbon water production technologies are indispensable for achieving sustainable development goals and mitigating global climate change. However, at present, many advanced water treatment processes lack a systematic assessment of related greenhouse gas (GHG) emissions. Thus, quantifying their life-cycle GHG emissions and proposing strategies toward carbon neutrality is urgently needed. This case study focuses on electrodialysis (ED), an electricity-driven desalination technology. To analyze the carbon footprint of ED desalination in various applications, a life cycle assessment model was developed based on industrial-scale ED processes. For seawater desalination, the carbon footprint is 59.74 kg CO2-eq/metric ton removed salt, which is one order of magnitude lower than that of high-salinity wastewater treatment and organic solvent desalination. Meanwhile, the power consumption during operation is the main hotspot of GHG emissions. Power grid decarbonization and improved waste recycling in China are projected to reduce the carbon footprint up to 92%. Meanwhile, the contribution of operation power consumption is expected to reduce from 95.83% to 77.84% for organic solvent desalination. Through sensitivity analysis, significant non-linear impacts of process variables on the carbon footprint were determined. Therefore, it is recommended to optimize the process design and operation to reduce power consumption based on the current fossil-based grid. GHG reduction for module production and disposal should also be emphasized. This method can be extended to general water treatment or other industrial technologies for carbon footprint assessment and reducing GHG emission.

Chlorine resistant polyamide desalination membrane prepared via organic-organic interfacial polymerization

Desalination of seawater, brackish water and urban sewage is an important way to solve the global water shortage. Polyamide (PA) membranes, including reverse osmosis (RO) membrane and nanofiltration (NF) membrane, are the primary technology for seawater desalination and clean water production. However, traditional thin-film composite PA (TFC-PA) membranes prepared from interfacial polymerization (IP) of amine monomers (either piperazine or m-phenylenediamine) in water and acyl chloride monomers in organic solvent are incapable of tolerating strong acid and chlorine environment. Here, we develop a new IP process, which takes place at the immiscible interface between dimethylacetamide (DMAc) and hexane (referred to as organic/organic IP), to prepare both chlorine-resistant and acid-resistant TFC-PA membranes. Compared to conventional water/oil IP process, the organic/organic IP process can adapt more kinds of amine monomers rather than just PIP, such as tetra (4-aminophenyl) methane (TMAP), tris (4-aminophenyl) amine (TAPA), and 4,4′,4''-(1,3,5-triazine-2,4,6-triyl) triphenylamine (TTA), which we studied in this work, thereby extending the PA molecular structure and enabling the membranes with greatly improved chemical stability. Among them, the TAPM-based TFC-PA membrane exhibits a NaCl rejection of 95.9% and no obvious NaCl rejection deterioration after soaking in a high concentration of NaClO (1000 ppm, pH 7) for more than 30 h, indicating excellent chlorine resistance. The TTA-based TFC-PA membrane shows a Na2SO4 rejection of 97% and remains unchanged after being exposed to a wide pH scan of 2–12. The Organic/organic IP provides a new and easy-to-operate platform for designing chlorine and acid resistant TFC-PA membranes, which will greatly improve their environmental stability as the most advanced desalination membrane at present.

Plasma-enabled graphene quantum dot-based nanofiltration membranes for water purification and dye monitoring

Nanofiltration (NF) is one of the key technologies for wastewater recycling and clean water production. However, current nanofiller-based NF membranes have been hampered by the inefficient separation due to the low water transportation and self-fouling of the membranes. Here we report a unique self-diagnosis bioresource-derived nitrogen-doped graphene quantum dots (NGQDs)-based thin-film nanocomposite (TFN) membrane with controlled optical properties and tuned porous nanostructures for ultrahigh water transportation and purification. Our detailed experimental and calculation studies suggest that the NGQDs with nanoscale sizes and abundant surface functional groups can induce the formation of desired porous structures during the membrane fabrication, leading an ultrahigh water permeability of 289 L m−2 h−1 bar−1 (LMHB) and remarkable 99.96% separation efficiency of various organic dyes. Moreover, the stable photoluminescence (PL) emission of NGQD membranes enables the PL-based monitoring of dye-fouling during the water purification. Our work provides a green manufacturing of nanomaterials-based membranes with defined structures and an understating of molecular transport in nanoscale.

Long-term performance evaluation of CO2 heat pump water heater under different discharge pressure control strategies

CO2 heat pump water heater has raised considerable attention as an environmentally efficient technology for hot water production. However, after long-term operation, the deterioration of component performance will not only directly cause system performance degradation, but also lead to a deviation of discharge pressure from the actual optimum under different discharge pressure control strategies, further resulting in additional performance loss. So far, the additional performance loss in the long run has not been in-depth investigated. In this study, based on a validated system model of CO2 heat pump water heater with component performance degradation factors, the long-term additional loss of system performance under eight different discharge pressure control strategies are compared. The results reveal that additional performance loss in the long-term operation can be significant under certain control strategy and working conditions. As for the investigated system, the control strategy with the parameter group of ambient and gas cooler outlet temperatures is favorable for application under the nominal operating condition with long-term degradation of heat exchangers, and the average additional loss of COP (coefficient of performance) can be decreased to 0.62%. As for the compressor degradation, the optimal refrigerant charge management strategy is preferred with an average COP loss as low as 0.05% under certain working conditions. In facing with year-round performance degradation, the control strategy with the parameter group of evaporating temperature and gas cooler outlet temperature shows better robustness, since the average additional annual performance loss can be reduced to only 2.52%.

Engineering Materials to Enhance Light-to-Heat Conversion for Efficient Solar Water Purification

Water scarcity has become one of the most prevalent problems afflicting people throughout the world and is expected to grow worse in the future due limited resources and increasing demand. This problem calls out for an urgent need to develop inexpensive, stand-alone desalination and water purification technologies that can adopt water resource distribution, water quality conditions, economic status, and developing levels of communities. Solar energy is abundantly available and has become one of the most promising emerging strategies in sustainable water treatment technologies. In this review paper, we highlight the recent progress of solar-driven desalination and water purification technologies for clean water production. We begin by introducing the fundamental concepts of solar radiation, solar thermal conversion, and heat localization. Then, we review the key components of solar steam generation including solar-thermal conversion materials, water pathways, and heat insulators and the strategies to promote efficient solar-to-vapor conversion in terms of chemical regulation, structural engineering, and heat management to maximize solar absorption and to minimize heat loss. Next, we discuss an efficient design of a solar steam generation device using an integrated approach that accounts for the performance of photothermal materials, heat losses, and water supply with respect to the hot evaporation region. Last, existing challenges and future opportunities in both fundamental studies and practical implementations of solar steam generation for water purification are discussed.

Hygroscopic-Microgels-Enabled Rapid Water Extraction from Arid Air.

Sorbent-based atmospheric water harvesting (AWH) has emerged as a promising decentralized water-production technology to mitigate the freshwater crisis in arid areas. Hydrogels have been regarded as attractive sorbents due to their high water retention and tailorable polymer-water interactions. Yet, the kinetics of water sorption and desorption at low relative humidity (RH) shall be improved for their practical implementation. Here, hygroscopic microgels (HMGs) composed of hydroxypropyl cellulose (HPC) and hygroscopic salt are reported, which achieve a water uptake of ca. 0.5-0.8g g-1 at 15-30% RH. HMGs enable rapid sorption-desorption kinetics owing to the short-distance diffusion in the microgels and hydrophilicity-hydrophobicity switching of the thermoresponsive HPC. To validate the feasibility of HMGs for moisture extraction, a potential daily water collection of up to equivalent 7.9-19.1 L kg-1 at low RH is demonstrated, enabled by 24-36 operation cycles per day based on the material-level experiments. With renewable raw materials and superior performance, HMGs provide a sustainable approach for rapid moisture extraction in arid climates.

Photothermal Aerogel Beads Based on Polysaccharides: Controlled Fabrication and Hybrid Applications in Solar-Powered Interfacial Evaporation, Water Remediation, and Soil Enrichment.

Solar-powered interfacial evaporation has emerged as an innovative and sustainable technology for clean water production. However, the rapid, mass and shape-controlled fabrication of three-dimensional (3D) steam generators (SGs) for versatile hybrid applications remains challenging. Herein, composite aerogel beads with self-contained properties (i.e., hydrophilic, porous, photothermal, and durable) are developed and demonstrated for threefold hybrid applications including efficient solar-powered interfacial evaporation, water remediation, and controlled soil enrichment. The rational incorporation of selected polysaccharides enables us to fabricate bead-like aerogels with rapid gelation, continuous processing, and enhanced ion adsorption. The composite beads can attain a high water evaporation rate of 1.62 kg m-2 h-1 under 1 sun. Meanwhile, high phosphate adsorption capacity of over 120 mg g-1 is achieved in broad pH (2.5-12.4) and concentration (200-1000 mg L-1) ranges of phosphate solutions. Gratifyingly, we demonstrate the first example of recycling biomaterials from interfacial SGs for controlled nutrient release, soil enrichment, and sustainable agriculture. The phosphate-saturated beads can be gradually broken down in the soil. Macronutrients (N, P, and K) can be slowly released in 50 days, sustaining the plant germination and growth in a whole growth stage. This work shines light on the mass and controlled fabrication of aerogel beads based on double-network biopolymers, not merely scaling up solar-powered interfacial evaporation but also considering water remediation, waste material disposal, and value-added conversion.