Water Harvesting Systems Research Articles

Hydrogel-embedded vertically aligned metal-organic framework nanosheet membrane for efficient water harvesting

AbstractHighly porous metal-organic framework (MOF) nanosheets have shown promising potential for efficient water sorption kinetics in atmospheric water harvesting (AWH) systems. However, the water uptake of single-component MOF absorbents remains limited due to their low water retention. To overcome this limitation, we present a strategy for fabricating vertically aligned MOF nanosheets on hydrogel membrane substrates (MOF-CT/PVA) to achieve ultrafast AWH with high water uptake. By employing directional growth of MOF nanosheets, we successfully create superhydrophilic MOF coating layer and pore channels for efficient water transportation to the crosslinked flexible hydrogel membrane. The designed composite water harvester exhibits ultrafast sorption kinetics, achieving 91.4% saturation within 15 min. Moreover, MOF-CT/PVA exhibits superior solar-driven water capture-release capacity even after 10 cycles of reuse. This construction approach significantly enhances the water vapor adsorption, offering a potential solution for the design of composite MOF-membrane harvesters to mitigate the freshwater crisis.

Sustainable Agricultural Practices in Sub-Saharan Africa: A Review of Adoption Trends, Impacts, and Challenges Among Smallholder Farmers

Sustainable agricultural practices (SAPs) remain the panacea to addressing challenges relating to climate change, low rainfall, and low agricultural productivity in many rural parts of sub-Saharan Africa (SSA). These practices include but are not limited to crop rotation, intercropping, cover cropping, and conservation tillage. The aforementioned practices have been scientifically proven to enhance crop productivity while safeguarding environmental resources. This review assesses the trends, effectiveness, and challenges associated with the adoption and utilization of SAPs among smallholder farmers in the SSA region, analyzing the literature and reports from 2000 to 2024 sourced from databases such as Google Scholar and Scopus. The inclusion criteria focused on key concepts such as SAPs, adoption, and challenges. Findings indicate that crop rotation, intercropping, improved seed varieties, manure, and mulching are among the most adopted practices. In reality, practices such as conservation tillage, agroforestry, and water harvesting systems remain the least adopted practices in many rural parts of SSA. The review further reveals that challenges relating to land tenure insecurity, lack of knowledge, training, and limited access to financial institutions all have a direct or indirect influence on farmers’ choice of adoption. Overcoming the aforementioned challenges through policy interventions and capacity building is vital for improved crop productivity and rural livelihoods.

Looking back to look forward: Explorations on water scenario in Bundelkhand, Central India

At present, India is suffering from the worst water crisis in its history, and millions of lives and livelihoods are under threat. As per NITI Aayog’s1 Water Index Report (2018), 40% of the population will have no access to drinking water by 2030. A 2016 report by Down To Earth (DTE) stated that 116,000 water harvesting structures were constructed between 2006 and 2015, and 15,000 crore rupees were spent on drought-proofing measures in Bundelkhand, Central India. Still, the region had 15th consecutive crop loss and 13 droughts in the past 15 years. Water historians like Elizabeth Whitcombe, Rohan D’Souza, and others have demonstrated how British imperialism led to the replacement of traditional water harvesting structures and systems, severely altering existing water-society relationships. On the contrary, Ian Stone, David Mosse, and Esha Shah argued that the ‘pre-colonial equilibrium’ versus ‘colonial hydrology’ framework is an exaggeration. Within this context, the research reveals the tangled roots of various causes and variables, and practically informing policy circles to tackle contemporary water issues and challenges and achieve SDG 6: Clean Water and Sanitation.

Biomimetic Superhydrophobic Triboelectric Surface Prepared by Interfacial Self‐Assembly for Water Harvesting

AbstractExtracting water from air offers a promising route to address the global challenge of water scarcity. However, bionic engineering surfaces for water harvesting often struggle with efficiently coordinating droplet nucleation and desorption. The recently emerging triboelectric effect at the liquid–solid interface offers a novel approach for developing bionic fog harvesting surfaces. In this study, inspired by Namib Desert beetles and lotus leaves, a biomimetic superhydrophobic surface with nanoscale hydrophilic domains is prepared via interfacial self‐assembly, exhibiting heterogeneous wettability for effective water harvesting. The essence of interfacial self‐assembly lies in the synergy of non‐covalent interaction forces, driving the self‐assembly of nanoparticles into surface micro‐nano hierarchical structures, thereby regulating wettability and increasing potential nucleation sites. Additionally, the triboelectric effect can directly utilize the triboelectric charges to facilitate droplet migration. The triboelectric effect can be generated by flexible mechanical input induced by walking, which enhances interfacial mass transfer, thereby rapidly improving droplet removal and achieving a 39.02% increase in water harvesting efficiency. This study has opened up a new breakthrough for the design of portable and efficient water harvesting systems.

Fresh water production via atmospheric water harvesting using solar energy for green hydrogen production

Abstract Solar energy is used to drive an atmospheric water harvesting unit to produce fresh water needed for the electrolysis process to produce hydrogen, as well as to drive the electrolyzer. So, the system can be considered as a solar powered hybrid system for fresh water harvesting and green hydrogen production implementing the electrolysis concept. Implementation of the system specially in arid regions with high levels of water scarcity and high relative humidity levels helps in achieving SDGs 3, 7, 9, and 13 progressively, improving health and wellbeing, reducing water scarcity, using clean renewable energy, and limiting climate change. The system is proposed and investigated for the production of both fresh and clean water and green hydrogen gas. To improve the productivity of the overall system, performance enhancement of the atmospheric water harvesting subsystem is experimentally investigated to assure the reliability and continuous operation of the overall green hydrogen hybrid system. It was investigated in summer and winter using different number of porous sheet metals with the silica gel bed. The results show that the productivity of the atmospheric water harvesting system can be increased by a minimum of 6% with one mesh metal sheet and 30% with two meshes, and increases by a maxinmum of 60% with one mech and 260% with two meches.

Thermoresponsive nanofiber yarns for water harvesting enhanced by harp system

The escalating global water crisis necessitates innovative approaches to developing sustainable water resources. Fog water collectors with variable surface wettability offer controlled fog harvesting in water-scarce regions. This study develops thermoresponsive fog collecting materials by electrospinning poly(N-isopropylacrylamide)-polyvinylidene fluoride (PNIPAm-PVDF) into yarns that are transformed into harp-like structures for enhanced water harvesting rate. Both meshes and harps using electrospun membranes exhibit the remarkable ability to transition between hydrophilic and hydrophobic wetting states at temperatures below the lower critical solution temperature (LCST). Hydrophilic and hydrophobic surfaces play distinct roles in fog water collection. Hydrophilic surfaces have a high affinity for water and enables droplet capture. Hydrophobic surfaces help the removal of aggregated water droplet and fog water collection. The highest water collection rate obtained with the electrospun PNIPAm-PVDF harp was 1415 ± 7.0 mg·cm−2 h−1. The water harvesting system based on the electrospun PNIPAm-PVDF harps exhibits a 485 % increase in water collection compared to the standard meshes made from the same material, emphasizing their potential for significantly improving the overall rate in fog water harvesting applications.

Solar driven atmospheric water harvesting system with integration of desiccant wheel and desiccant bed: An experimental investigation

Solar-driven atmospheric water harvesting (SDAWH) presents a promising solution to address water scarcity issues, particularly in arid and semi-arid regions where conventional water sources are limited. This paper presents a new SDAWH system, integrated with a desiccant wheel and desiccant bed. The desiccant bed adsorbs water vapour during night and desorbs in a day time. Whereas the desiccant wheel performs adsorption and desorption process simultaneously in day time. Therefore, the combination of these offers the potential to enhance water yield and energy efficiency compared to conventional sorption-based SDAWH systems in semi-arid climate. Further, an evacuated tube solar air heater for regeneration and an air-to-air heat exchanger for condensation of water vapour has been integrated. The desiccant bed releases large amount of water vapour in regeneration air but its desorption gradually decreases with time. On the other hand, the desiccant wheel releases a lesser quantity of water vapour into the regeneration air, but its desorption capacity remains almost constant. The system’s performance has been evaluated in a semi-arid climate. As the system is working in closed cycle, the dew point temperature of regeneration air obtained at the outlet of the desiccant wheel is 39.4 °C, which increases to 42.4 °C at the outlet of the desiccant bed. The total yield of water in a day is 7.6 L, with an energy efficiency of 9 %.

3D printed Ti3C2@Polymer based artificial forest for autonomous water harvesting system

The escalating scarcity of freshwater resources presents significant challenges to global sustainability, demanding innovative solutions by integrating cutting-edge materials and technologies. Here we introduce an autonomous artificial forest (3D AF) for continuous freshwater acquisition. This system features a three-dimensional (3D) architecture incorporating a carbon nanofiber (CNF) network and MXene@polypyrrole (Ti3C2@PPy), enhancing surface area, light absorption, heat distribution, and surface wettability to improve solar vapor generation and fog collection efficiency. The autonomous operation is facilitated by an integrated photothermal actuator that adjusts to the day and night conditions. During daylight, the 3D AF tilts downward to maximize solar exposure for water evaporation, while at night, it self-adjusts to optimize fog particle collection. Notably, our device demonstrates the ability to harvest over 5.5 L m−2 of freshwater daily outdoors. This study showcases the potential of integrating advanced materials and technologies to address pressing global freshwater challenges, paving the way for future innovations in water harvesting.

Integrated Impact of Olive Mill Wastes and Semi-Circular Bunds on Soil Properties and Rainwater Harvesting Efficiency in Egypt’s Northwestern Coastal Zone

ABSTRACT The productivity of olive in the northwestern coastal zone of Egypt is significantly constrained by drought and low organic matter in the soil. This study addresses these challenges by exploring the synergistic effects of olive mill wastes (OMW) application and micro-catchment water harvesting techniques on soil properties, runoff, moisture storage, and rainwater harvesting efficiency. Field experiments were conducted over two winter seasons, employing different micro-catchment structures (semi-circular and triangular bunds) and OMW applications. The results revealed that the integration of semi-circular bunds with OMW application (T4) substantially increased rainwater harvesting efficiency by 67.7% and 46.4% in the first and second seasons, respectively. Additionally, T4 and T5 exhibited reduced runoff by 47.8% and 41.3% in the first season and 49.4% and 38.9% in the second season, respectively. T4 significantly enhanced soil organic matter, soil macronutrients (N, P, and K), and micronutrients (Fe, Mn, Zn, and Cu) compared to the control (T1). The study highlights the effectiveness of T4 in improving soil moisture, reducing soil erosion, and enhancing soil fertility. This integrated approach involving OMW application within a semi-circular bund as a water harvesting system proves to be a promising strategy for sustainable olive cultivation in arid conditions.

Optimizing Building Orientation for Passive Cooling

This research paper explores the application of passive design strategies in three museums in Lagos, Nigeria: The National Museum, Jaekel House, and the Heritage Museum in Badagry. The study focuses on building orientation as a key passive design strategy and evaluates its effectiveness in enhancing energy efficiency and thermal comfort in tropical climates. With the use of data collection from Google Earth Pro, a comparative analysis examines the architectural features and design elements of each museum, highlighting their use of building orientation, shading devices, and landscaping to optimize passive cooling and natural lighting. The innovative layout and strategic orientation of the National Museum demonstrate a successful integration of passive design strategies, while Jaekel House's use of deep overhangs and vegetation showcases a deliberate commitment to sustainable architecture. The Heritage Museum in Badagry, with its historical significance, presents an intriguing case study for passive design. While limited information is available, satellite imagery suggests an optimal orientation for passive solar design, complemented by deep overhangs and a reflective roof. The findings suggest that the three museums can benefit from further enhancements to their passive design strategies, including the integration of renewable energy sources, smart building systems, green roof systems, and water harvesting and management systems. In addition, educational initiatives can raise awareness and promote sustainable practices among visitors and the local community.

Protecting ancient water harvesting technologies in India: strategies for climate adaptation and sustainable development with global lessons

IntroductionAncient water harvesting systems, such as those from the Indus Valley Civilization (~3500 BCE), have been vital for irrigation and climate resilience, especially in arid regions. One such prominent system in South Asia, called tank irrigation, initially thrived through community management but declined post-independence due to colonial policies and neglect in Sri Lanka and India. This study evaluates current policy frameworks and rehabilitation programs to enhance the resilience of these systems in India, develop strategies for their protection and adaptation to climate change, and integrate global lessons for sustainable development.MethodsA systematic meta-analysis of grey literature was conducted to aggregate data on policy constraints. Policy analysis involved detailed investigations of relevant documents, regulations, and comparative analyses of frameworks at regional and national levels. Pilot projects on tank rehabilitation were assessed through reported case studies and field surveys to gauge impact. Thematic analysis was used to explore the global potential of these systems in climate resilience and overall environmental sustainability.ResultsThe analysis showed that pilot projects for tank rehabilitation had limited success in achieving sustainability under current climate conditions. Tank irrigation systems are crucial for adapting to extreme weather, including floods, droughts, and heat waves, replenishing groundwater, reducing soil erosion, and ensuring reliable water supplies. Traditional water harvesting technologies support 17 Sustainable Development Goals (SDGs), including clean water access, hunger reduction, gender equality, and climate action. Integrating AI and machine learning in water management benefits disaster response, while eco-tourism aids system maintenance and cultural awareness.DiscussionThe study underscores the need for policy reforms to enhance tank rehabilitation and institutional arrangements. It calls for increased beneficiary participation and constitutional recognition of current practices. Strategic, national-scale assessments and resilience targets are recommended to improve the effectiveness of such water harvesting systems in mitigating natural hazards and enhancing environmental services.

Kinetics of Water Adsorption in Metal-Organic Framework(MOF-303) for Adsorption Cooling Application

Adsorption cooling systems (ACS) powered by low-temperature heat offer an energy-efficient and environmentally friendly alternative to traditional vapor-compression systems. The effectiveness of ACS is significantly influenced by the alignment of the adsorbent properties with the operating conditions of the cycle. Metal-Organic Frameworks (MOFs) are considered the next generation of water harvesting and ACS. Many MOFs are synthesized and tested for water harvesting systems, one of these MOFs is MOF-303 which was reported to have very rapid water sorption dynamics under atmospheric conditions. However, MOF-303 has never been tested under the same conditions as ACS (under vacuum). In this study, the isotherms and kinetics of water adsorption on MOF-303, as an efficient adsorbent of water vapor, is experimentally investigated for the ACS using the linear driving force model. The diffusion coefficients across a wide range of relative pressures under two different temperatures were estimated. The study compares the adsorption process of MOF-303 with traditional silica gel (SG) in the context of diffusion kinetics relevant to ACS. Based on the output and at a constant temperature of 25 °C and across all relative pressure ranges, MOF-303 exhibited an average increase of approximately eight times in diffusion kinetics compared to SG. Specifically, within the relative pressure range of 10–30 %, which is optimal for ACS, MOF-303 demonstrated a seven-fold increase in diffusion kinetics over SG. The diffusion values for SG display a clear upward trend with increasing temperature. In contrast, the diffusion values for MOF-303 are subject to fluctuations with temperature changes under investigation. Notably, the isotherm for MOF-303 shows an inflection point at relative pressures between 10–15 %, causing a significant reduction in diffusion at these specific relative pressures compared to other relative pressure values. The findings in this study highlight the potential use of MOF-303 as a highly efficient water adsorbent for the ACS which will enable scientists and engineers to develop sustainable low-grade energy systems.

Internally-cooled atmospheric water harvesting enabling improved productivity

Sorption-based atmospheric water harvesting holds promise for alleviating water scarcity, but current prototypes have not shown significant increases in practical yields despite efforts in the enlarged engineering scale. This is due to weakened heat and mass transfer with a packed sorbent bed. In this work, the desiccant-coated adsorbers were employed to fabricate the water harvesting device that incorporates internal fluid for cooling and heating during sorption and desorption. Featured with an internal cooling effect, practical water productivity could be improved by 1.75–9.96 times with a low desorption temperature (45–62 °C). The continuous water harvesting system could produce 0.77–3.98 Lwater/kgsorbent/day with a thermal energy consumption of 7.7–30.4 MJ/kg in wide climates from 20 % to 80 % RH, providing a reference for device design in the engineering view. The demonstration revealed that using natural cooling in the sorption stage has great benefits in improving water harvesting performance, which can be integrated into the building sectors or a wider range of scenarios.

Experimental comparison of solar‐powered adsorption‐based atmospheric water harvesting using air‐to‐air & water‐to‐air heat exchanger for condensation

AbstractAdsorption‐focused technologies for atmospheric water harvesting is of great importance. Most of the available systems in the literature use glass as a condenser, which gets heated up. This restricts vapor condensation to harvest less water and hampers the system's scalability. The effectiveness of the proposed solar atmospheric water harvesting system, which uses an air‐to‐air fin‐tube heat exchanger to condense the vapors, is experimentally evaluated in this work. In order to assess the system's effectiveness using a water‐to‐air fin‐tube heat exchanger, a comparison study is also carried out. The experimental setup consists of evacuated tube solar air heater having 8.46 m2 area and 15 kg silica gel adsorbent. The performance metrics for comparison include adsorption & regeneration rate, thermal, overall and exergy efficiency, along with economic analyses. The system harvests 1890 mL/day of water using air‐to‐air heat exchanger at cost of 0.19 $/l, achieving thermal, overall & exergy efficiencies of 21.66%, 2.24%, and 6.51%, respectively. On the other hand, the water‐to‐air heat exchanger based system harvests maximum of 2680 mL/day of water at a cost of 0.14 $/l, achieving thermal, overall & exergy efficiencies of 25.65%, 3.34%, and 9.13%, respectively. Moreover, the produced water is confirmed to be safe for consumption.

Optimal Design of Air Treatment for an Adsorption Water-Harvesting System

In some areas where access to water is difficult, such as arid regions, it is a feasible measure to acquire water from the air. In this context, a system for water harvesting from the air was designed and manufactured. In order to find the optimal operation parameters of the system, the humidity–enthalpy diagram and the dehumidifier computation software (V2.0, Win7) were adopted for the optimization work. The air treatment process of the system was analyzed and calculated by using the professional software provided by the dehumidifier company. Operation modes of ‘powerful mode’ and ‘economic mode’ were defined in the computation work, which are represented by the water production amount and efficiency (water production per power consumption), respectively. According to computation analysis, the relationships between the main performance indicators and the system design/operation parameters were obtained. By considering the heating power limitation of the system, the wheel dehumidifier rotation speed of 8 rph (revolutions per hour), zonal area ratio of Ap/Ar = 2, and the optimal airflow ratios in different relative humidity (RH) environments, together with the outlet air parameter settings of the surface cooler, were finally defined.

Feasibility Study of Aquawall - An Alternative for Conventional Rain Water Harvesting System

Rainwater harvesting has been an age-old activity, practiced by many cultures in areas of poverty and wealth, but unfortunately our urban communities discard using it due to ignorance and lack of education. The challenge is to change the attitude of the state agencies responsible for environmental policy to make population being part of water saving, reduction of vulnerability and adaptation to climate change with rainwater harvesting. In our urban space limitations make it necessary to propose a system of “vertical water tank” that fulfills this function. The Aquawall project is based on the appropriate technology and the circular economy, made by self and is designed in a modular way, taking up minimal space, made of nine towers of six three-liter bottles each, connected to a PVC base

Design of TETHYS: a greenhouse plant-smart water harvesting and air-cleaning system

Design of TETHYS: a greenhouse plant-smart water harvesting and air-cleaning system

3D Bionic Water Harvesting System for Efficient Fog Capturing and Transporting

AbstractFog harvest has emerged as a direct and efficient water harvesting technology to relieve the intense pressure of freshwater scarcity worldwide. With the vagaries of climate and increasing amount of energy consumption, high‐efficiency fog harvest devices focus on the fast water droplet capture and transportation are highly desired. In this study, a novel harp structure is developed using cross‐twisted copper filaments arranged in a spatial triangular pattern to enhance water droplet capture and transportation. Inspired by the natural differences in Laplace pressure observed in cactus and spider silks, this design accelerates the movement of water bridges. Besides, drawing on the fruit waxes on the surface of hogweed and blueberries, a paraffin wax coating is applied on the copper sheet frame to create a solid slip frame, improving the synergy between filament capture and frame transportation. The monolithic fog collector (MFC) thus achieves a significant increase in fog harvest efficiency and demonstrates excellent durability. Integration of the MFCs into a 3D high‐efficiency fog harvest system results in a harvest rate of 0.5027 g cm−2 min−1, showing promise for practical applications due to its durability, simplicity, and environmental friendliness.

ESTIMATION OF GREEN BUILDING OVER CONVENTIONAL BUILDING

This report investigates the comparative costs and benefits of green building versus conventional building practices. By integrating five advanced techniques: Biophilic Design, Passive House Design Strategies, Digital Twin Technology, Net Zero Energy Techniques, and Water Harvesting System into the construction of a conventional building, we transformed it into a green building at an additional cost of approximately ₹6,72,420. The total cost for constructing the green building amounted to ₹24,23,876.78, inclusive of the base cost of a conventional building. The study outlines a comprehensive methodological approach, which includes creating theoretical models, conducting cost analyses using current market rates in India, and evaluating environmental impacts through carbon emissions calculations. The findings reveal that although the initial costs for green buildings are higher, they offer substantial long-term benefits, including reduced operational expenses, improved occupant health, and minimized environmental footprints. Green buildings are designed to maximize resource efficiency, enhance indoor air quality, and utilize renewable energy sources, resulting in significant energy savings and reduced carbon emissions. This investment in sustainable construction practices not only promotes environmental stewardship but also ensures economic viability through long-term savings and improved occupant well-being. The transition to green buildings is a crucial step towards addressing climate change and fostering sustainable development for future generations. This report underscores the importance of adopting green building techniques and demonstrates that the benefits far outweigh the initial financial outlay, making green buildings a worthwhile investment for a sustainable future.

Necessity and Design of Roof Top Rain Water Harvesting System

Necessity and Design of Roof Top Rain Water Harvesting System