Efficient Water Research Articles

Industrial circular water use practices through the application of a conceptual water efficiency framework in the process industry

Increased industrial water demand and resource depletion require the incorporation of sustainable and efficient water and wastewater management solutions in the industrial sector. Conventional and advanced treatment technologies, closed-water loops at different levels from an industrial process to collaborative networks among industries within the same or another sector and digital tools and services facilitate the materialization of circular water use practices. To this end, the scope of this paper is the application of the Conceptual Water Efficiency Framework (CWEF), which has been developed within the AquaSPICE project aspiring to enhance water circularity within industries in a holistic way. Four water-intensive process industries (two chemical industries, one oil refinery plant and one meat production plant) are examined, revealing its adaptability, versatility and flexibility according to the requirements of each use case. It is evident that the synergy of process, circular and digital innovations can promote sustainability, contribute to water conservation in the industry, elaborating a compact approach to be replicated from other industries.

Structure engineering and surface reconstruction enabling MoNi4 hollow nanocube for efficient urea-assisted water electrolysis

Nickel-based electrocatalysts are identified as the promising candidates for both urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) in urea-assisted water electrolysis to accelerate energy saving hydrogen production. However, the high occupation of Ni 3d orbital leads to their constrained adsorption for reactant and multiple intermediates during UOR process. Herein, considering the d-band electron complementation, the bimetallic MoNi4 hollow nanocubes self-assembled with numerous ultrathin nanosheets was constructed by introducing molybdenum with relatively empty d orbital and synergistically boost UOR/HER activities. Notably, the MoNi4 requires a lower cell voltage of 1.462 V to drive a current density of 10 mA cm−2 in urea electrolyzer, superior to that in water electrolyzer (1.796 V) and most of the reported nickel-based electrocatalysts, as well as the urea degradation rate is impressive. In situ technologies including electrochemical impedance spectroscopies and Raman spectra reveal that the favorable UOR pathway can be initiated directly by the reconstructed NiOOH species. Density functional theory (DFT) calculations prove that the urea molecular are preferential absorbed on Ni site and then collaborate with the adjacent Mo site to carry out the subsequently dehydrogenation, N-N coupling, and desorption in energetically favorable pathways, proving their dual site mechanism (synergy between Mo and Ni).

P–N homojunction and heteroatom active site engineering over Fe2O3 nanorods for highly efficient photoelectrochemical water splitting

Limited charge transfer and slow oxygen evolution (OER) kinetics significantly impede the practical realization of photoanodes for photoelectrochemical (PEC) water splitting. Here, pn-type-Fe2O3 homojunction photoanode catalysts with P active sites are designed by doping phosphorus (P) into outer lattice of n-type Fe2O3 nanorods (pn-P-Fe2O3). The optimized pn-P-Fe2O3 photoanode shows the maximum photocurrent density of 2.61 mA/cm2 at 1.23 VRHE, and the value is 6.4 times greater than that of pristine Fe2O3. Experimental and theoretical results clearly show that the P–N homogeneous junctions constructed in Fe2O3 through P-doping increase active sites for H2O adsorption and activation, reduce OER reaction energy barrier, and promote effective separation of photogenerated electron-hole pairs and water splitting kinetics. This not only makes the photoelectric water decomposition performance outstanding, but also produces excellent durability. This work provides a novel simple and environmentally friendly strategy for designing effective photoanodes for PEC water splitting.

Regulating the surface properties and interlamellar spacing of GO-based nanofiltration membrane for efficient water treatment

Regulating the surface properties and interlamellar spacing of GO-based nanofiltration membrane for efficient water treatment

Impacts of Bacillus amyloliquefaciens and Trichoderma spp. on Pac Choi (Brassica rapa var. chinensis) grown in different hydroponic systems.

Soilless production systems (i.e hydroponics, aeroponics, aquaponics) have become commonplace in urban settings and controlled environments. They are efficient nutrient recyclers, space savers, and water conservers. However, they lack high levels of biological richness in the root microbiome when compared to soil production systems, which may affect plant health and nutrient uptake. To address this issue and incorporate more sustainable practices, beneficial microorganisms (i.e. Trichoderma spp., Bacillus sp.) can be added in the form of biofertilizers. However, many factors affect impacts of microorganisms and their interactions with plants. In this experiment, Black Summer Pac Choi (Brassica rapa var. Chinensis) was grown for two trials in a Deep-Water system (DWS) or a Nutrient Film Technique system (NFT) with commercial biofertilizers containing Trichoderma spp., Bacillus amyloliquefaciens, a combination of both, and a control. Plant physiology, nutrient composition, and nutrient uptake efficiency (NUE) were generally negatively affected by Trichoderma spp. both growing systems, indicating that Trichoderma may not be recommended for hydroponic production. However, Bacillus amyloliquefaciens showed promise as an effective biofertilizer in the NFT systems and had a positive influence on NUE in DWS.

3D Biomass‐Based Interfacial Solar Steam Generation: Component, Optimization, and Application

The seawater desalination and wastewater treatment by the interfacial solar steam generation (ISSG) technique is considered as a green, economical, sustainable, low‐energy‐consumption, and potential fresh water production strategy to solve the water shortage and energy crisis. Recently, efficient biomass‐based ISSGs (BISSGs) have been widely reported due to its efficient photothermal conversion efficiency and good hydrophilic performance. The BISSGs with efficient solar absorption and water transmission performance by design and optimization their various forms and structures and related photothermal properties is also significantly great for its scale application. This review highlights recent advancements in 3D BISSG systems, with a focus on the design and optimization of photothermal conversion materials and substrate materials. Then, the review also discusses the potential of biomass materials in BISSG applications, aiming to provide a theoretical basis for developing cost‐effective, efficient, and sustainable water purification technologies. Finally, the challenges and development prospects of the BISSG system in basic research and practical application will provide theoretical guidance for the further development of this technology.

Construction of Ag/AgCl@MIL-53(Fe): Achieving Efficient Photocatalytic Water Oxidation via the Plasma-Phase Silver and Heterojunction Synergistic Effect

The development of highly efficient water oxidation catalysts is a bottleneck in achieving artificial photosynthesis, as water oxidation is a complex process involving multiple electron and proton transfers. To further improve the photocatalytic water oxidation performance of MIL-53(Fe), a series of Ag/AgCl@MIL-53(Fe) samples with different Fe:Ag ratios were synthesized by hydrothermal methods and used in the photocatalytic water oxidation reactions. XRD characterization showed the successful preparation of Ag/AgCl@MIL-53(Fe) heterostructure catalysts. The reaction results showed that sample AAM-2 (Fe:Ag=5:1) had the best photocatalytic water oxidation performance, with the highest TOF value of 0.14 mmol/(g·s) and quantum efficiency of 39.0 % under the conditions of catalyst mass of 1 mg and pH=9.0 for boric acid-borax buffer solution. Measurements of photocurrent indicated that the AAM-2 samples doped with Ag/AgCl had higher photocurrent densities, thus improving the photocatalytic performance. This provides new insights for constructing highly efficient porous MOFs catalysts.

Reconstruction of Ferromagnetic/Paramagnetic Cobalt‐Based Electrocatalysts under Gradient Magnetic Fields for Enhanced Oxygen Evolution

AbstractThe rational manipulation of the surface reconstruction of catalysts is a key factor in achieving highly efficient water oxidation, but it is a challenge due to the complex reaction conditions. Herein, we introduce a novel in situ reconstruction strategy under a gradient magnetic field to form highly catalytically active species on the surface of ferromagnetic/paramagnetic CoFe2O4@CoBDC core–shell structure for electrochemical oxygen evolution reaction (OER). We demonstrate that the Kelvin force from the cores’ local gradient magnetic field modulates the shells’ surface reconstruction, leading to a higher proportion of Co2+ as active sites. These Co sites with optimized electronic configuration exhibit more favorable adsorption energy for oxygen‐containing intermediates and lower the activation energy of the overall catalytic reaction. As a result, a significant enhancement in OER performance is achieved with a large current density increment about 128 % at 1.63 V and an overpotential reduction by 28 mV at 10 mA cm−2 after reconstruction. Interestingly, after removing the external magnetic field, the activity could persist for over 100 h. This work showcases the directional surface reconstruction of catalysts under a gradient magnetic field for enhanced water oxidation.

Environmental impact of modern agricultural practices: Strategies for reducing carbon footprint and promoting conservation

Modern agricultural practices have significantly transformed food production, leading to increased efficiency and productivity. However, these advancements have also had notable environmental impacts, particularly concerning carbon emissions and resource depletion. This study explores the environmental impact of contemporary agricultural practices, emphasizing the need for strategies to mitigate carbon footprints and enhance conservation efforts. Agriculture contributes substantially to greenhouse gas emissions through sources such as livestock, synthetic fertilizers, and fossil fuel consumption. These emissions contribute to climate change and global warming. Additionally, modern farming practices often lead to deforestation, habitat loss, and soil degradation, exacerbating biodiversity loss and reducing soil health. Water usage in agriculture also poses significant challenges, with high water consumption and pollution from runoff affecting water resources and aquatic ecosystems. To address these issues, several strategies can be employed to reduce the carbon footprint of agriculture. Adoption of sustainable farming practices such as conservation tillage and no-till farming can enhance soil carbon sequestration, improving soil health and reducing emissions. Agroforestry and cover cropping further contribute by capturing atmospheric carbon and improving soil structure. The integration of renewable energy sources like solar and wind power in farming operations, along with energy-efficient technologies, can also reduce reliance on fossil fuels and lower overall greenhouse gas emissions. Promoting conservation involves implementing practices that protect and restore natural resources. Soil conservation methods, including erosion control techniques like terracing and contour plowing, help maintain soil health and prevent degradation. Efficient water management strategies, such as drip irrigation and rainwater harvesting, reduce water consumption and mitigate pollution from runoff. Biodiversity conservation can be supported through the preservation of natural habitats and the promotion of biodiverse farming systems, which enhance ecosystem resilience and stability. Effective policy frameworks and support mechanisms are crucial for driving the adoption of these strategies. Government policies, including environmental regulations and incentives, play a pivotal role in encouraging sustainable practices. Research and innovation are essential for developing new technologies and practices, while education and extension services ensure the dissemination of knowledge and best practices to farmers. Modern agricultural practices have significant environmental impacts, but through the adoption of sustainable practices and innovative strategies, it is possible to reduce carbon footprints and promote conservation. Continued research, supportive policies, and effective implementation of conservation strategies are essential for achieving a more sustainable agricultural future. Keywords: Environmental Impact, Agricultural Practices, Carbon Footprint.

Evaluation of crop water stress index of wheat by using machine learning models.

The Crop Water Stress Index (CWSI), a pivotal indicator derived from canopy temperature, plays a crucial role in irrigation scheduling for water conservation in agriculture. This study focuses on determining CWSI (by empirical method) for wheat crops in the semi-arid region of western Uttar Pradesh, India, subjected to varying irrigation treatments across two cropping seasons (2021-2022 and 2022-2023). The aim is to investigate further the potential of four machine learning (ML) models-support vector regression (SVR), random forest regression (RFR), artificial neural network (ANN), and multiple linear regression (MLR) to predict CWSI. The ML models were assessed based on determination coefficient (R2), mean absolute error (MAE), and root mean square error (RMSE) under diverse scenarios created from eight distinct input combinations of six variables: air temperature (Ta), canopy temperature (Tc), vapor pressure deficit (VPD), net solar radiation (Rn), wind speed (U), and soil moisture depletion (SD). SVR emerges as the top-performing model, showcasing superior results over ANN, RFR, and MLR. The most effective input combination for SVR includes Tc, Ta, VPD, Rn, and U (R2 = 0.997, MAE = 0.901%, RMSE = 2.223%). Meanwhile, both ANN and MLR achieve optimal results with input combinations involving Tc, Ta, VPD, Rn, U, and SD (R2 = 0.992, MAE = 2.031%, RMSE = 3.705%; R2 = 0.759, MAE = 13.95%, RMSE = 19.98%, respectively). For RFR, the ideal input combination comprises Tc, Ta, VPD, and U (R2 = 0.951, MAE = 5.023%, RMSE = 9.012%). The study highlights the considerable promise of ML models in predicting CWSI, proposing their future application in integration into an irrigation decision support system (IDSS) for crop stress mitigation and efficient water management in agriculture.

Optimization of carrier transfer kinetics of BiOIO3 using TFA·/TFA- reversible redox pairs of TFA molecules as co-catalysts for efficient photoelectrochemical water splitting system

Co-catalyst loading on photoelectrodes is considered to be an effective way to accelerate charge transfer. However, the bonding between most of the co-catalysts and photoelectrodes tends to be weak, which severely limits the role of co-catalysts in the catalytic system. Based on the above problems, we introduced trifluoroacetic acid (TFA) as a homogeneous molecular co-catalyst in the layered BiOIO3 catalytic system for the first time. The BiOIO3-TFA photoelectrode exhibited excellent photoelectrochemical performance under light and applied bias voltage. The photocurrent density reached up to 0.228 μA cm−2, which was 2.11 times higher than that before modification, while the overpotential was negatively shifted by 183 mV. The results showed that the photogenerated electron-hole pairs in BiOIO3 are excited and transferred to the TFA causing the CO double bond to break to form a TFA radical (TFA·), which is then reduced to TFA-. This cyclic redox reaction accompanied by fast hole transfer can greatly reduce the recombination behavior during carrier transport. This work demonstrates a new form of co-catalyst for photoelectrochemical water splitting. Highly water-soluble molecules and TFA·/TFA- reversible reactions have considerable potential for the development of new co-catalysts. It also provides ideas for the establishment of new, efficient catalytic systems for inhibiting carrier recombination.

Advanced design of metal single-atom (Pt, Mn, Fe or Cu) loaded S-Ni(OH)2 nanosheets array catalysts to achieve high-performance overall water splitting

Designing catalysts at atomic level fine-tune the electronic structure of surface-active site for efficient water splitting, is a highly desirable approach but also poses significant challenges. This study focuses on the synthesis of a series of electronically tunable metal single-atom (M−SAs) catalysts: M9@S-Ni(OH)2 (M=Pt, Mn, Fe or Cu). Experimental results reveal that introduction of trace S-heteroatoms and metal atoms into Ni(OH)2 lattice can effectively modulate the electronic structure of M9@S-Ni(OH)2 through modulation of p-d and d-d orbital hybridization, resulting in exceptional performance in water electrolysis. Among M9@S-Ni(OH)2, Pt9@S-Ni(OH)2 and Fe9@S-Ni(OH)2 exhibit excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance, respectively, the overpotential requiring only 7 mV and 269 mV, respectively, at current density of 10 mA cm−2. (−) Pt9@S-Ni(OH)2||Fe9@S-Ni(OH)2 (+) presents a high current density of 531.07 mA cm−2 at cell-voltage of 1.80 V in overall-water splitting (OWS), which is 14.07 times higher than that of the commercial (−) Pt/C||IrO2 (+) (37.86 mA cm−2) system. This work achieves the development of cost-effective and stable electrocatalysts, offering a solution for large-scale and sustainable water-hydrogen conversion.

Are Water Use Efficiency and Effectiveness Relatively Lower in Arid Zones? Comparative Analyses of the Water Productivity of Typical Crops

Agriculture is the largest water user of all sectors. In arid regions in particular, achieving efficient water use in agriculture is an important way to solve water scarcity. However, the difference in water use efficiency between arid and humid regions has long been a focus of academic debate. Many studies consider water use efficiency to be higher in humid areas due to the abundance of water resources. This view is based on the fact that less irrigation in humid areas may lead to higher crop yields and better conditions for agricultural production; however, it ignores the efforts of researchers and agricultural workers in arid zones who have attempted to develop efficient water-saving technologies, as well as the effect of natural conditions on agricultural production. Correctly evaluating the efficiency of agricultural water use in arid zones is important for achieving efficient use of water resources, as well as for water management decisions. This study calculates the yield structure and water productivity of typical crops in both arid and humid regions in China based on the footprint theory and other methodologies. This approach allows for an accurate assessment of irrigation water benefits in various regions, providing a scientific basis for improving agricultural water use efficiency under different climatic conditions. The study results indicate that the average reliance on blue water for wheat and cotton gradually increases from 49.9% to 93.6% as regional aridity intensifies, ranging from the Central China Humid Region to the Northwest China Arid Region. Similarly, the average contribution of blue water to crop yield rises from 31.0% to 100%, while irrigation water productivity increases from 0.27 kg·m−3 to 0.53 kg·m−3. Finally, this study concludes that, in arid zones with lower precipitation and more hours of sunshine, a higher dependence on blue water for crop growth and development leads to a higher productivity of irrigation water. In addition, in arid zones, the focus should be on optimizing the use of irrigation water and improving irrigation technology and efficiency, while, in humid zones, there should be more use of natural precipitation to efficiently reduce dependence on irrigation water.

Tailoring the selective generation of high-valent cobalt-oxo by asymmetrically coordinated single-atom cobalt-activated peracetic acid for efficient water decontamination

The novel nonradical Fenton-like oxidation based on high-valent cobalt-oxo [CoIVO] species is a promising candidate for selectively removing emerging organic contaminants (EOCs) in complex water; however, efficient and targeted generation of CoIVO is hampered by the high Co-3d orbital occupancy and high bond dissociation energy of deprotonation. Herein, an O doping strategy to construct asymmetric coordination (CoN3O) in Co single-atom catalyst (Co-SAC) is developed to steer peracetic acid (PAA) activation for selectively generating CoIVO. Theoretical calculations suggest that asymmetric coordination of CoN3O could induce significant electron delocalization around Co centers, thus promote adsorption and peroxy O–O bond cleavage of PAA. The asymmetric electronic structure also exerts an additional local electric field, which favors the cleavage of O–H bond via a proton-coupled electron transfer pathway for subsequent CoIVO generation. Consistent with the theoretical prediction, the established CoN3O/PAA system exhibits admirable Fenton-like activity in degrading various EOCs to low-toxicity intermediates through exclusive generation of CoIVO, greatly reducing potential environmental risks. Our work provides a fundamental understanding of the structure–activity–selectivity relationships at an atomic level and provides a design guide to develop advanced CoIVO-involved Fenton-like catalyst for more extensive applications.

Construction of NiFe/MnNiCo-LDH heterostructure for enhanced oxygen evolution reaction for efficient water splitting

Developing highly efficient and cost-effective oxygen evolution reaction (OER) catalysts is pivotal for advancing sustainable energy storage and conversion technologies. Herein, NiFe/MnNiCo-LDH was successfully prepared by in-situ growth method. The OER performance of this composite material had been significantly enhanced through bimetallic atom modification and cation doping strategies. These modifications not only enhanced the electronic conductivity but also regulated the electron distribution within the catalyst structure. As a result, NiFe/MnNiCo-LDH can reach a current density of 10 mA cm−2 at an overpotential of only 227 mV in the OER reaction. Moreover, the catalyst exhibited remarkable durability and maintained its high performance over an extended period of 48 h during the water splitting reaction. In this work, the potential of dual modification methods for optimizing catalytic properties of OER materials was investigated.

Designing a Novel C3‐Fe‐N Interface Local Coordination Microenvironment for Efficient Electrocatalytic Water Splitting

Designing a Novel C₃‐Fe‐N Interface Local Coordination Microenvironment for Efficient Electrocatalytic Water Splitting

Sustainable and Low-Input Techniques in Mediterranean Greenhouse Vegetable Production

In the modern agricultural landscape, numerous challenges, such as climate change, diminishing arable lands, and the reduction of water resources, represent significant threats. The Mediterranean greenhouse farming model relies on low-input strategies to maximize both yield and quality. Its protected horticulture is essential for the year-round cultivation of high-value crops, ensuring efficient and sustainable production. In the realm of future agricultural strategies, leveraging internet-based approaches emerges as a pivotal factor for real-time and remote control of various agricultural parameters crucial for crop growth and development. This approach has the potential to significantly optimize agronomic inputs, thereby enhancing the efficiency of targeted vegetable production. The aim of the present review is to underscore the challenges related to the intensive greenhouse production systems emphasizing various strategies leading to low-input greenhouse vegetable production. The goal is to promote more sustainable and resource-efficient approaches in the cultivation of greenhouse vegetables. This review highlights several key strategies for optimizing the greenhouse environment, including efficient water management through conservation tillage, drainage water reuse, and selecting the most appropriate irrigation systems and timing. Additionally, light modulation and temperature control—using solar energy for heating and pad-and-fan systems for cooling—are crucial for enhancing both crop performance and resource efficiency. The review also explores low-input agronomical strategies, such as pest and disease control—including solarization and optimized integrated pest management (IPM)—as well as fertilization and advanced growing techniques. These approaches are essential for sustainable greenhouse farming.

Efficient atmospheric water harvesting enabled by hierarchically structured cellulose foam

The sorption-based atmospheric water harvesting technique is an appealing solution for addressing the challenge of freshwater shortages. In this study, a composite foam was fabricated by confining hygroscopic salt (CaCl2) into a Cr-based metal–organic framework (MIL-101), which was then integrated into a bacterial cellulose (BC) skeleton. The hierarchical structure, which contains micron- and nanoscale pores, enhances water storage, transport, and vapor evaporation throughout the whole water capture and release process. The pore confinement effect of MIL-101 and the interconnected BC network effectively restricted the leakage of the liquefied salt solution. Interestingly, the color of the CaCl2@MIL-101@BC foam changed from light green to dark green as the amount of absorbed water increased. This moisture-induced color darkening improves the light absorption ability during the water release stage under sunlight. At 30 % relative humidity, the foam can absorb up to 0.78 g g−1 of water per cycle (8 h) and desorb quickly under solar radiation. This makes foam a promising method for water production in arid areas.

Evaluating a vertical greening system mesocosm for kitchen greywater treatment: Comparison among vegetation species in water consumption, biomass growth and pollutants uptake and removal

The escalating climate imbalance, coupled with rising water demands in rapidly expanding urban areas, is forcing scientists and policymakers to seek alternative strategies for efficient water resource management. Nature Based Solutions (NBS) are gaining prominence due to their ability to provide multiple ecosystem services. However, the quantification of benefits and drawbacks mediated by different vegetation species remains inadequate. In this study, we investigated the performance of a pot-based vertical greening system (VGS) designed to integrate the functions of green facades with those of treatment wetlands. The VGS was vegetated with Mentha aquatica L. (hereafter Mentha), Oenanthe javanica (Blume) DC. (hereafter Oenanthe) and Lysimachia nummularia L. (hereafter Lysimachia), and their respective effects on water balance and mass removal of common greywater pollutants were compared. Results indicated that VGS lines vegetated with Oenanthe and Mentha exhibited comparable pollutant removals. Oenanthe showed a preference for greywater that had already undergone partial treatment, while Mentha was not affected by any pollutant load in water removal −48.1 % of total inflow– and in nutrients uptake in aboveground biomass −14.3 % N and 7 % P– due to sustained and robust growth, outperforming Oenanthe and Lysimachia. This has suggested the potential use of Oenathe in combination with Mentha for enhanced performances, particularly given Oenanthe's rapid growth in the early season and high biomass and nitrogen content following initial greywater treatment.

Per- and polyfluoroalkyl substances contamination of drinking water sources in Africa: Pollution sources and possible treatment methods

Despite the detection of poly- and perfluorinated alkyl substances (PFAS) in the water system in Africa, the effort towards mitigating PFAS in water in Africa needs to be better understood. Therefore, this review evaluated the contamination status and mitigation methods for handling PFAS-contaminated water systems in Africa. The findings revealed the presence of PFAS in wastewater treatment plant (WWTP) effluents, surface water and commercially available bottled and tap water in African countries. The concentration of PFAS in drinking water sources reviewed ranged from < limits of quantification to 778 ng L−1. The sources of PFAS in water systems in Africa are linked to uncontrolled importation of PFAS-containing products, WWTP effluents and inappropriate disposal of PFAS-containing materials. The information on treatment methods for PFAS-contaminated water systems is scanty. Unfortunately, the treatment method is challenged by poor water research infrastructure and facilities, lack of awareness, poor research funding and weak legislation; however, adsorption and membrane technology seem favourable for removing PFAS from water systems in Africa. It is essential to focus on monitoring and assessing drinking water quality in Africa to reduce the disease burden that this may cause. Most African countries' currently implemented water treatment facilities cannot efficiently remove PFAS during treatment. Therefore, governments in Africa need to fund more research to develop an efficient water treatment technique that is sustainable in Africa.