Freshwater Scarcity Research Articles

Maximization of brackish water productivity for the sustainable production of striped catfish (Pangasianodon hypophthalmus) and grain sorghum (Sorghum bicolor (L.) Moench) cultivated under an integrated aquaculture–agriculture system

Freshwater scarcity, salinity, and poor soil fertility are the major challenges affecting both food and feed productions in arid and semi-arid regions of the world. Utilization of brackish water in the production of saline-tolerant fish and valuable field crops under an integrated system is promising in the maximization of yield per crop. The aim of this study, therefore, was to (1) assess the effect of saline aquaculture wastewater on the growth, yield, forage quality, and nutritive composition of sorghum seeds and (2) assess the effect of different water qualities on the survival, growth performance, and health status of Pangasianodon hypophthalmus. The experiment was conducted in a randomized completely block design of four salinity treatments with three replicates, i.e., control (freshwater mixed with inorganic fertilizers), 5000 ppm, 10,000 ppm, and 15,000 ppm. Our results indicated that although the control exhibited the highest growth (plant height, leaf number, internode number, leaf area, and soil–plant analysis development), grain, and forage yield, no significant differences were noted among the treatments. Likewise, no significant difference in the grain nutrient composition was noted among all the treatments. Assessment of the forage quality revealed improved crude protein content in the control compared to the saline treatments. However, no significant differences in the leaves and stalks fiber fractions were noted among all the treatments. Furthermore, rumen fermentation in terms of in vitro digestibility indicated no significant differences in the in vitro digestible dry matter, digestible organic matter, metabolic energy, net energy, microbial protein, short-chain fatty acids, and total dissolved nutrients among the treatments. However, rearing P. hypophthalmus in water salinities exceeding 10,000 ppm reduced the growth performance and health status of fish. Therefore, the integration of sorghum and P. hypophthalmus production in water salinities not exceeding 5000 ppm is a viable alternative to maximize brackish water productivity in freshwater-scarce regions.

Assessment of a sustainable technology-based novel humidifier system

The present study aimed at fulfilling the necessity of thermal comfort air in a defined space. A novel -humidifier system where the grey/saline water is filtered and used in an evaporative cooling system to fulfil the requirements of thermal comfort air. Water is made to pass through the first stage of packing to filter the contaminated water, and it is filtered again in a humidifier packing section, which then mixes with air to undergo humidification with reduction in its temperature. Experiments were conducted to evaluate, air quality, and system performance. Various humidification parameters such as humidification efficiency, coefficient of performance (COP), change in pressure and specific humidity were determined. Experimental results indicated that, with the rise in the liquid-to-gas ratio, there is a rise in a change in temperature, specific humidity and COP. The system yielded maximum efficiency, pressure drop, COP, specific humidity change, and a temperature drop of 84 %, 270 Pa, 1.85, 1 g/kg and 5.3 °C respectively. Air quality measurement revealed that departing air offered good thermal comfort without any pollution. Therefore, the innovative system proves beneficial in hot areas that experience significant cooling demands, such as countries in the Middle East, which also face a scarcity of fresh water.

Identifying true collectorless flotation of chalcopyrite in calcium chloride solutions

Given the increasing use of seawater containing primary ions (e.g. Na+ and Cl-) and secondary ions (e.g. Ca2+ and Mg2+) in flotation plants to counteract the global freshwater scarcity, more and more studies have been performed to determine the impacts of seawater on mineral flotation behaviors. From a new and practical niche, this study aimed to determine the natural floatability of chalcopyrite in the presence of Ca2+ as a secondary ion by considering the alterations of surface hydrophobicity from both the aspects of surface oxidation and metal ion precipitation. Through true collectorless flotation, Cyclic Voltammetry analyses, calcium speciation and Cryogenic X-ray Photoelectron Spectroscopy measurements, this study identified that the true flotation recovery of chalcopyrite was much lower in CaCl2 solutions than in NaCl solutions even with the same ionic strengths. While the presence of NaCl enhanced chalcopyrite surface oxidation to produce hydrophobic and hydrophilic products, the presence of CaCl2 inhibited chalcopyrite surface oxidation through the formation of CaCO3 precipitate which not only served as a passive layer but also being hydrophilic itself. As a result, the surface hydrophobicity on chalcopyrite was determined by the amount of oxidation products in NaCl solutions, but it was determined by the amount of CaCO3 precipitate in CaCl2 solutions. Despite the larger amount of CaCO3 precipitate in CaCl2 solutions with ionic strengths of 0.7 and 1.2 M, compared to deionized water and CaCl2 solution with an ionic strength of 0.1, the true flotation recovery of chalcopyrite was higher. This was attributed to much smaller air bubbles generated in CaCl2 solutions with high ionic strengths of 0.7 and 1.2 M, promoting bubble-particle collision and hence the true flotation of chalcopyrite.

Advancement of membrane separation technology for organic pollutant removal.

In the face of growing global freshwater scarcity, the imperative to recycle and reuse water becomes increasingly apparent across industrial, agricultural, and domestic sectors. Eliminating a range of organic pollutants in wastewater, from pesticides to industrial byproducts, presents a formidable challenge. Among the potential solutions, membrane technologies emerge as promising contenders for treating diverse organic contaminants from industrial, agricultural, and household origins. This paper explores cutting-edge membrane-based approaches, including reverse osmosis, nanofiltration, ultrafiltration, microfiltration, gas separation membranes, and pervaporation. Each technology's efficacy in removing distinct organic pollutants while producing purified water is scrutinized. This review delves into membrane fouling, discussing its influencing factors and preventative strategies. It sheds light on the merits, limitations, and prospects of these various membrane techniques, contributing to the advancement of wastewater treatment. It advocates for future research in membrane technology with a focus on fouling control and the development of energy-efficient devices. Interdisciplinary collaboration among researchers, engineers, policymakers, and industry players is vital for shaping water purification innovation. Ongoing research and collaboration position us to fulfill the promise of accessible, clean water for all.

Thermodiffusive desalination

Desalination could solve the grand challenge of water scarcity, but materials-based and conventional thermal desalination methods generally suffer from scaling, fouling and materials degradation. Here, we propose and assess thermodiffusive desalination (TDD), a method that operates entirely in the liquid phase and notably excludes evaporation, freezing, membranes, or ion-adsorbing materials. Thermodiffusion is the migration of species under a temperature gradient and can be driven by thermal energy ubiquitous in the environment. Experimentally, a 450 ppm concentration drop was achieved by thermodiffusive separation when passing a NaCl/H2O solution through a single channel. This was further increased through re-circulation as a proof of concept for TDD. We also demonstrate via molecular dynamics and experiments that TDD in multi-component seawater is more amenable than in binary NaCl/H2O solutions. Numerically, we show that a scalable cascaded channel structure can further amplify thermodiffusive separation, achieving a concentration drop of 25000 ppm with a recovery rate of 10%. The minimum electric power consumption in this setup can be as low as 3 Whe m−3, which is only 1% of the theoretical minimum energy for desalination. TDD has potential in areas with abundant thermal energy but limited electrical power resources and can contribute to alleviating global freshwater scarcity.

Eco-emotions as the planetary boundaries: framing human emotional and planetary health in the global environmental crisis

BackgroundAffective processes play an important role in physical and mental health and in adaptation responses to the global environmental crisis. Eco-emotions—emotions that are substantially associated with the environment and anthropogenic changes happening within it—are complex and culturally varied. Despite the disproportionate impact of the global environmental crisis on low-income and middle-income countries, most psychological research to date has been conducted in high-income countries and has focused on climate change and negative climate emotions (eg, climate anxiety). The absence of diverse, globally representative evidence about emotions associated with the global environmental crisis beyond climate change hinders evidence-based action on psychological adaptation and the development of contextually and culturally appropriate coping strategies toward the wider range of negative anthropogenic effects. To account for this wider range of anthropogenic effects, we previously introduced an eco-emotions framework built on the planetary boundaries concept. We aimed to apply this framework to the current research on eco-emotional responses to identify remaining gaps that hinder evidence-based action. MethodsWe conducted a literature review of peer-reviewed studies assessing core affect (ie, emotional valence and arousal) and emotions with emphasis on study populations from low-income and middle-income countries and on the eight non-climate change planetary boundaries (biodiversity loss, freshwater use, ocean acidification, chemical pollution, air pollution, land system change, ozone depletion, and nitrogen and phosphorus perturbation). We searched Web of Science from database inception to Oct 31, 2023, for observational empirical studies of adults, using planetary boundary-specific (eg, freshwater use) or wider, newer, or overarching emotional concept (eg, solastalgia, environmental change) search terms. FindingsIn contrast to previous climate emotions work, our preliminary results of 135 peer reviewed studies identified a significant body of literature beyond climate change concerning emotional responses to the planetary boundaries of biodiversity loss, freshwater scarcity, and chemical pollution as well as emerging evidence of emotional responses to the other five planetary boundaries. InterpretationWe found that the spectrum of eco-emotional responses ranged from being specific to a single planetary boundary to encompassing all planetary boundaries. Our findings underscore the importance of and urgent need for more holistic and diverse psychological intervention strategies targeting the wider range of anthropogenic effects during the rapidly intensifying global environmental crisis. FundingEmmett Interdisciplinary Program in Environment and Resources; McGee and Levorsen Research Grant Program; and Center on Philanthropy and Civil Society at Stanford University.

Utilizing Hybrid RO-OARO Systems as New Methods for Desalination Process

The scarcity of fresh water and its essential role in sustaining life on Earth have motivated researchers to seek new, low-cost, scalable technologies for water desalination. Therefore, the osmotically assisted reverse osmosis (OARO) membrane process presents an innovative approach to achieve moderate water recoveries from high salinity water without undergoing a phase change. This work aims to investigate the performance of hybrid RO-OARO systems with various designs and operational parameters on recovery and R%. The hybrid systems were evaluated for 60 minutes at feed concentrations of 3.98-5.54 g/l, applied pressures ranging from 3 to 7 bars, and different membrane types. The results showed that the flux of the hybrid system increased by increasing the pressure and decreased by increasing the feed concentration. The highest recovery value was obtained for the RO-OARO system at an RO pressure of 7 bar and an OARO unit at 3 bar for a 3.98 g/l feed concentration. In contrast, when the reverse osmosis pressure was fixed at 5 bar, and the pressure of the OARO unit increased by 2 bar, the recovery value exceeded by about 6%. Furthermore, the FilmTech membrane showed the highest recovery at 31.7%, while the highest R% was 94.55% for the AquaTec membrane. The RO-OARO-OARO system contributed to increasing both the recovery and rejection values by 11.4 and 2.1%, respectively, compared with the RO-OARO system. The experiments in this study revealed a slight increase in the feed concentration of the reverse osmosis unit, indicating the efficiency of the hybrid systems compared to traditional RO systems.

Group VIII (Fe, Co, and Ni) based water evaporators for solar driven interfacial water evaporation: Performance optimization, applications and recent advances

Solar-driven interfacial evaporation (SDIE) is a promising technology for sustainable and efficient production of clean water, addressing the pressing issue of freshwater scarcity facing humanity. Given the high level of concern regarding this matter, it is crucial to continuously summarize the research achievements of predecessors to further advance SDIE technology. This review first discusses the key role of solar absorbers containing Group VIII elements, including Fe, Co, and Ni, in SDIE. Second, it explores strategies to improve SDIE performance, such as increasing light absorption, regulating water transport channels, implementing effective thermal management, and reducing the enthalpy of water evaporation. These strategies can effectively optimize the performance of the evaporator and improve energy utilization efficiency. Further, this review details the specific applications of SDIE technology in areas such as seawater desalination, wastewater treatment, and energy reuse. We aim to provide insights for developing stable and efficient SDIE systems, promoting their practical applications, and developing other potential applications.

Enhancing pakchoi (Brassica chinensis L.) agriculture with magnetized-ionized brackish water and organic fertilizers: A sustainable approach to soil quality and crop yield optimization

The scarcity of freshwater, the increasing use of brackish water (B) for irrigation, and the judicious application of organic fertilizers have significant research and practical value for environmental science, water resource management, and clean production. This study investigated the combined impact of B, magnetized-ionized brackish water (MIB), and organic fertilizer on pakchoi (Brassica chinensis L.) growth, yield, and soil quality. Over a two-year period (2022–2023), this study explored the impacts of two types of irrigation water (B and magnetized-ionized brackish water, MIB) in combination with varying rates of water-soluble bio-organic fertilizer (0, 20, 40, 60, and 80 kg/ha, corresponding to treatments 0 through 4, respectively). The findings indicated that the application of 60 kg/ha of organic fertilizer greatly improved the growth rate of pakchoi in terms of plant height, leaf area index, and fresh weight. Moreover, under MIB irrigation, the fresh weight growth rate of pakchoi was superior to that observed under B irrigation. Notably, B irrigation necessitated additional fertilizer to maintain elevated levels of alkali-hydrolyzed nitrogen (AN) and soil quality. Furthermore, the use of organic fertilizer substantially enhanced soil quality, with AN, available phosphorus (AP), organic matter (OM), and soil quality index (SQI) demonstrating a strong positive correlation (P < 0.05). Mantel test analysis showed significant correlations (P < 0.05) between soil OM, SWC, AP, and pakchoi growth and yield. According to the partial least squares path modeling analysis, the use of organic fertilizer had a relatively minor effect on the yield and quality of pakchoi under B irrigation, with path coefficients of 0.088 and 0.298, respectively. However, under MIB irrigation, organic fertilizer enhances yield and quality by improving soil quality (path coefficients of 0.914). In conclusion, the application of MIB irrigation coupled with organic fertilizer contributed to sustainable soil fertility, enhanced crop productivity, and mitigated the environmental impacts associated with conventional irrigation and fertilization methods. Our research underscores the importance of supporting agricultural research and development focused on sustainable irrigation and fertilization methods for farmers and policymakers. This integrated approach offers a harmonious solution for optimizing crop yields and enhancing water use efficiency, and the reduction of in chemical pollutants within agricultural production systems.

Biodesalination of saline aquaculture wastewater with simultaneous nutrient removal and biomass production using the microalgae Arthrospira and Dunaliella in a circular economy approach

Freshwater scarcity is escalating due to factors such as climate change, droughts, increased demand, population growth, and poor water management practices. A promising sustainable solution to this challenge is biodesalination using microalgae. We demonstrate that Arthrospira platensis and Dunaliella salina can thrive in saline aquaculture wastewater, reducing both its salinity and the concentration of nutrients. The salinity removal ability was quantified through measurements of electrical conductivity (EC) and ICP-OES, revealing reductions in EC by up to 45 % (from 31.5 to 17.2 ms/cm) for A. platensis and 35 % (from 31.5 to 20.5 ms/cm) for D. salina. FESEM indicated the formation of a salt layer on the surface of both microalgae, suggesting biosorption and bioaccumulation as likely mechanisms. FTIR spectroscopy analysis demonstrated the binding of functional groups within the cell wall of A. platensis and the cell membrane of D. salina with the ions present in the medium. Scaling up the cultivation of A. platensis in a photobioreactor under non-sterile conditions validated the processes' potential for industrial-scale biodesalination. Although the treated water did not reach the standards for irrigation or potable use, this approach provides a preliminary desalination step, reducing burden on subsequent treatments and simultaneously providing nutrient removal and biomass production.

Optimal design and economic analysis of a stand-alone integrated solar hydrogen water desalination system case study agriculture farm in Kairouan Tunisia

In the contemporary global discourse on environmental and developmental issues, the dual challenges of sustainable green energy and water supply stand paramount. These elements are vitally intertwined with the socio-economic vitality of the world. Notably, regions plagued by freshwater scarcity are increasingly turning to desalination which consists of a reliable and unconventional water source. The intersection of renewable energy with desalination and water purification processes presents a compelling synergy. This approach is particularly pertinent in areas where freshwater shortages coexist with abundant solar energy availability. Additionally, these technologies boast the advantage of low operational and maintenance costs. This paper delves into the design, optimization and financial analysis of a novel, standalone hybrid energy system, integrating photovoltaic and fuel cell technologies, for an agriculture farm situated in Kairouan, Tunisia. Unlike conventional systems, this model foregoes battery storage in favour of hydrogen storage, generated through water electrolysis powered by solar energy. This system harnesses solar energy for direct electrical power generation and hydrogen gas production. A segment of the generated electricity is allocated to electrolysis for green hydrogen production. In times of solar unavailability, the stored hydrogen is reconverted to electricity via a fuel cell. An intriguing aspect of this system is the utilization of saline well water, which, due to its high salt content, necessitates purification through desalination to prevent damage to the electrolysis unit and to render it suitable for agricultural irrigation.

Elevated Uptake and Translocation Patterns of Heavy Metals in Different Food Plants Parts and Their Impacts on Human Health.

Irrigation with contaminated wastewater is a common practice in cultivation of crops and vegetables in many developing countries due to the scarcity of available fresh water. The present study has investigated the transfer and mobilization trends of heavy metals in different crops and vegetables plants grown in contaminated soil and waterbody. The translocation patterns of metals from polluted sources into different organs of plants bodies such as roots and edible parts and associated health risks have been evaluated simultaneously. Total of 180 different environmental samples including food plants, agricultural soil, and irrigation water were collected and analyzed. Heavy metal concentrations (Fe, Ni, Mn, Pb, Cu, Cd, As) in water, soil, and different parts of crops and vegetable plants were compared with the permissible levels reported by FAO/WHO, EU, and USEPA. Different metals contents within the food plants were found to be in the order of Fe > Mn > Ni > Cu > Pb > Cd > As. Pollution load index (PLI) data indicate that soil is highly polluted with Cd as well as moderately contaminated by As and Cu. Bioconcentration factor (BCF) analysis showed excessive accumulation of some heavy metals in crops and vegetables. Target hazard quotient (THQ) and target carcinogenic risk (TCR) analysis data showed higher carcinogenic and non-carcinogenic risks for both adult and children from the consumption of metal-contaminated food items. The results of metal pollution index (MPI), estimated daily intake (EDI), and hazard index (HI) analyses demonstrated the patterns of metals pollution in different food plants.

Bioinspired construction of petal-like regenerated PVDF/cellulose fibers for efficient fog harvesting

Water collection from atmospheric fog was deemed to be an efficient and sustainable strategy to defuse the freshwater scarcity crisis. Fog harvesting and trapping fibers, therefore, has aroused extensive interest due to their ease of preparation, weave, and use. However, the traditional fibers used in fog collector usually have a low fog collection capacity and efficiency because of their unreasonable morphology and structure design. Herein, we proposed a simple process to construct advanced fibers using a one-step wet spinning of hydrophobic polyvinylidene fluoride (PVDF) and hydrophilic cellulose mixture fiber for fog harvesting. The as-prepared fibers featured a petaloid structure and surface hydrophobic gradient, thus facilitating fog deposition, water droplet formation, and drainage. The unique longitudinal groove structure above enabled the hybrid fiber to achieve an excellent fog collection efficiency of 2750.26 mg/cm2/h per monofilament, which outstripped most of other fiber materials. When woven these fibers were in a longitudinal array network with an interval of 1 mm, and the fog collection efficiency can maintain at 10.30 L/m2/h. Therefore, this work provided a new strategy for further exploration of effective fog collection by cellulose-based fiber materials.

Atmospheric air freshwater using TPMS compact heat exchangers

The technology of extracting freshwater from atmospheric air is currently accessible in tropical regions and is experiencing substantial growth in areas where freshwater scarcity is prevalent. Moreover, the water-cooling towers in power plants and district cooling chillers produce saturated air, which serves as a significant supply of humid air and consequently freshwater. Dehumidification is the necessary procedure for extracting water vapor from moist and saturated air in order to generate water. An efficient heat exchanger with a high ratio of surface area to volume is necessary to enhance the production of freshwater by condensing the water vapor present in the air. Triply periodic minimum surface (TPMS) structures possess intricate geometries, resulting in a high ratio of surface area to volume and intense turbulence. Consequently, these structures have exceptional heat transmission capabilities. The internal network structure of the TPMS enables the formation of a consistent layer of freshwater by direct interaction with humid airflow, resulting in a continuous flow. The objective of this study was to examine the structural architectures of TMPS that maximize the generation of freshwater from moist air under various humidity and flow conditions. This was achieved by employing accurate 3D computational fluid dynamics (CFD) models. The purpose of developing these models is to analyze the performance of the Gyroid-Solid TPMS structure and compare it to a vertical flat plate with the same surface area. Furthermore, the study examines the freshwater production efficiency of various TPMS designs (Gyroid-Solid, Gyroid-Sheet, and Diamond-Solid) with same porosity but varying levels of humidity in the air. The findings indicate that the Gyroid-Solid structure enhances the condensation flow rate by a threefold factor in comparison to the flat plate across different levels of humidity in the air. Furthermore, the findings indicated that Diamond-Solid exhibited superior performance when subjected to low airflow Reynolds numbers, whereas at high Reynolds numbers The Gyroid-Sheet exhibits the highest level of condensation among the three solid structures, surpassing the Diamond-Solid by 25% and the Gyroid-Solid by 65 %. The findings demonstrated a notable increase in the production of freshwater through the utilization of TPMS structures, thereby deepening our understanding of the crucial influence of geometry on the condensation process. Empirical formulae have been formulated to calculate the Nusselt number of atmospheric air for TPMS heat exchangers, taking into account various design and operational factors.

Holistic approach for fabrication of superhydrophobic MXene-based membrane for enhanced membrane distillation

There is growing interest in membrane distillation (MD) as a means of desalinating seawater with 100 % theoretical salt rejection which has the capacity to address freshwater scarcity. MD has huge potential for commercial applications owing to its low operating temperature and pressure requirements. However, wetting polymeric membranes inhibits water permeance and lowers salt rejection. MXene nanosheet-incorporated polyvinylidene (PVDF) membranes have been constructed for enhanced vapor transport with high water repellence and antiwetting properties. MXene nanosheets in PVDF polymeric matrices are responsible for their high super-hydrophobicity, which can mitigate membrane fouling and wetting during the MD process. As far as experimental outcomes are concerned, the pristine PVDF membrane exhibited severe wetting with salt leakage. Ti3C2Tx MXene nanosheets allow the formation of hierarchical polymeric micro/nanostructures, changing the intrinsic hydrophilicity to super-hydrophobicity. Surface engineering of a PVDF membrane with MXene nanosheets enables efficient saline desalination during the MD process. The surface-engineered MXene/PVDF membrane demonstrated a high-water contact angle of 143° with extremely high self-cleaning characteristics as compared to that of pristine PVDF membrane. As far as the performance of the membrane is concerned, the water flux of the pristine PVDF membrane decreased from 6.5 LMH to 6 LMH after the 14th hour which can be attributed to partial pores wetting during MD operation. Eventually, the pristine PVDF membrane exhibited a continuous salt flux (SF) increase. However, MXene/PVDF membrane showed stable water flux (8 LMH) and negligible SF. The study therefore demonstrates a facile and holistic approach for constructing MXene-based PVDF membranes that exhibit superior antiwetting performance during MD operation.

Bioinspired 1T-MoS2-based aerogel beads for efficient freshwater harvesting in harsh environments

Freshwater scarcity is one of the most critical issues worldwide, particularly in arid regions, stemming from population growth and climate change. Inspired by the hydrophilic bump structures of desert beetles, 1T-MoS2-based aerogel beads with porous structures and CaCl2-crystal loading (termed as MoAB-m@CaCl2-n) were prepared for freshwater harvesting. Metallic-phase MoS2 nanospheres exhibit excellent photothermal conversion abilities, facilitating solar-driven water desorption and evaporation. Owing to the synergistic effect of its localized surface features, hydrophilic groups, and dispersive CaCl2 particles, MoAB-2@CaCl2-2 efficiently harvests water from atmosphere with a superior moisture adsorption capacity (0.18–0.82 g g−1) at a wide range of relative humidity (10 %-70 %). Under one-sun illumination, MoAB-2@CaCl2-2 demonstrates an outstanding solar-driven water evaporation rate of 2.25 kg m-2h−1. The water evaporation rate from soil (water content = 20 %) is 1.19 kg m-2h−1, which is sufficient for sustainable freshwater generation from the soil in arid regions. More importantly, the multifunctional MoAB-2@CaCl2-2-based homemade freshwater generation prototype delivers a certain amount of water harvesting (0.99 g g−1 day−1) on a rainy day and provides an impressive daily freshwater yield (53.7 kg m−2) under natural sunlight. The integrated device exhibits excellent efficiency and practicality and offers a feasible method for freshwater harvesting in harsh environments.

Distillate yield improvement techniques for solar still coupled with evacuated tube collector: a review.

Many effective solutions to the problem of freshwater scarcity have been offered by the research community across the globe. Evacuated tube collector (ETC)-aided solar thermal desalination devices have succeeded magnificently in providing drinking water to the general public, especially in solar-rich isolated locations. Furthermore, heat transfer fluid ETC solar water desalination units are a much smarter, novel, and cost-effective solution that does not needed additional power and is well-suited to remote locations with a greater rate of self-sustainability. The efficiency of ETC-assisted solar distillation equipment as well as the essential analytical parameters related to the device and heat transfer fluid are thoroughly examined in this study. Literatures published in the last three decades are keenly reviewed and reported. The key finding reveals that solar still integrated with ETC can produce 3.5 to 4l of freshwater per m2 area with depth varying from 0.01 to 0.03m. It is discovered that the ETC-assisted solar still has a mean energy efficiency that is around 33% greater than the traditional solar still. When it comes to exergy efficiency, the ETC solar still outperforms conventional stills by 4%. Novel methods adopted for boosting the effectiveness of a solar still combined with ETC are reported for further research.

Learning-based multi-agent MPC for irrigation scheduling

Amid concerns about freshwater scarcity, the agricultural sector faces challenges in water conservation and optimizing crop yields, highlighting the limitations of traditional irrigation scheduling methods. To overcome these challenges, this paper introduces a unified, learning-based predictive irrigation scheduler that integrates machine learning and Model Predictive Control (MPC), while also incorporating multi-agent principles. The proposed framework incorporates a three-stage management zone delineation process, utilizing k-means clustering and hydraulic parameters estimates for optimized agro-hydrological modeling. Long Short-Term Memory (LSTM) networks are employed for accurate and computationally efficient root zone soil moisture modeling. The scheduler, formulated as a mixed-integer MPC with zone control, utilizes the identified LSTM networks to maximize root water uptake while minimizing overall water consumption and fixed irrigation costs. Additionally, the learning-based scheduler adopts a multi-agent MPC paradigm, where decentralized hybrid actor–critic agents and the concept of a limiting irrigation management zone are employed to enhance computational efficiency. Evaluating the performance on a 26.4-hectare field in Lethbridge for the 2015 and 2022 growing seasons demonstrates the superiority of the proposed scheduler over the widely-used triggered scheduling approach in terms of Irrigation Water Use Efficiency (IWUE) and total prescribed irrigation. Notably, the proposed approach achieves water savings between 7 to 23%, coupled with IWUE increases ranging from 10 to 35%.

Improving irrigated maize (Zea mays L.) production with saline agricultural drainage water using drip irrigation system and organic mulches: Field study and simulation modelling

Due to the scarcity of fresh water in dry areas, including Egypt, emphasis has been placed on the importance of studying non-traditional water sources as an alternative source of irrigation. Therefore, this research aimed at investigating the impact of saline agricultural drainage water, drip irrigation and organic mulching using rice straw on maize water productivity under Egypt’s arid condition. The field experiment included sixteen treatments during two seasons, 2022 and 2023. Irrigation systems were [Furrow irrigation system (FIS) and drip irrigation system (DIS)] while saline agricultural drainage water strategies were [FW (0.55 dS/m), SW1 (1.35 dS/m), SW2 (3 dS/m) and SW3 (5 dS/m)] represented as sub main plot and organic mulching using rice straw (OMRS) was also investigated. The highest MY values were achieved with DIS with FW and also with irrigation with salty agricultural drainage water, with the necessity of using organic mulches of rice straw. The highest MY values were achieved as a result of achieving the best water-salt balance within the root propagation zone. The highest values were 10.89 t/ha with FW and there were no significant differences between them and the values of 10.83 t/ha when irrigated with saline agricultural drainage water for 2022 and the similar results were achieved during the 2023 season. Based on the above, SW1 can be used directly without mixing with FW1 if the ability of the grown plant to tolerate the level of salinity concentration, with the necessity of using organic mulches. The SALTMED model simulated reasonably well the soil moisture and soil salinity as well as maize yield and for all treatments, with R2 of 0.87, 0.98 and 0.96, respectively.

Full tea waste-based photothermal aerogel with vertical water transport channels for steady solar desalination

Interfacial solar desalination technology holds immense promise in combatting global freshwater scarcity. However, salt accumulation on solar evaporators poses a significant hurdle in sustaining desalination performance. Therefore, the development of salt-resistance solar evaporators remains a formidable challenge. Herein, we have exploited a full tea waste-based photothermal aerogel (TWPA) to achieve steady desalination performance. This TWPA is fabricated with carbonized tea waste (TWC) and tea waste fiber (TWF) with a simple crosslinking method and liquid nitrogen freeze-drying. The TWPA efficiently absorbs 97% of sunlight, which results in an exceptional evaporation rate of 1.63 kg m–2 h–1 under 1-solar intensity. Moreover, the vertical water transport channels and large pore structure within TWPA expedite solution transport and salt ion backflow diffusion, ensuring stable desalination of 10 wt% brine at a rate of 1.37 kg m–2 h–1. Long-term indoor and outdoor experiments demonstrate that TWPA is durable. Notably, a 1 m2 TWPA can generate about 6.34 kg freshwater per day from 10 wt% brine. This simple waste-to-treasure approach not only demonstrates a sustainable solution but also promises to drive the development of waste-based solar evaporators, addressing freshwater scarcity while mitigating environmental pollution.