Seasonal atmospheric water harvesting yield and water quality using electric-powered desiccant and compressor dehumidifiers

Enhancing fog harvesting efficiency with a multi-object-coupled bio-inspired surface

The global freshwater crisis poses a substantial threat to sustainable development, driving urgent demand for advanced atmospheric water harvesting technologies. While bio-inspired fog collectors have shown potential, conventional single-scale architectures often exhibit suboptimal performance due to inadequate coordination between droplet nucleation and transport. Here we present a multi-object-coupled venation-shaped patterned surface (MVSS) fabricated through laser-etching of filter paper/polydimethylsiloxane composite films. By synergistically integrating three bio-inspired mechanisms: (i) heterogeneous wettability patterns mimicking desert beetle elytra, (ii) conical spine arrays inspired by Opuntia histophysiology, and (iii) hierarchical venation networks derived from plant leaf, we establish a multi-stage phase-transition process that enhances fog harvesting efficiency through coordinated surface energy gradients and Laplace pressure modulation. The wettability contrast enables selective droplet nucleation, while the conical geometry generates asymmetric contact line pinning that drives directional transport. The hierarchical branching network minimizes hydraulic resistance through optimized flow path partitioning, achieving rapid drainage while suppressing edge water accumulation. This multi-scale synergy yields a record water collection rate of 1033 ± 28.2 mg cm-2 h-1. Our findings elucidate the critical role of structure-property coordination in fog water collection, providing a generalized design paradigm for developing high-efficiency atmospheric water harvesters. The fabrication strategy combining scalable laser processing with bio-composite materials suggests promising pathways for arid region deployment.

Sorption-based atmospheric water harvesting for continuous water production in the built environment: Assessment of water yield and quality

Sorption-based atmospheric water harvesting (SAWH) is a promising solution for localized high-quality water production. Application of SAWH indoors offers dual benefits of on-site water generation and humidity control. This study evaluated the use of SAWH for water production in residential or office buildings, employing a portable zeolite-based SAWH device. Over the twelve-month testing period in the arid southwestern USA, the device achieved a median water yield of 3.6 L/day at a cost 30 % less than bottled water sold in the U.S. A mathematical model was developed for predicting water yield under different temperature and relative humidity (RH) conditions. Daily water yields were well fitted with the modified Langmuir model, with absolute humidity serving as the only prediction variable. Water extracted from a well-ventilated office building generally met the drinking water standards set by USEPA. However, elevated levels of dissolved organic carbon (DOC) were detected in the samples collected from the residential house (median = 32.6 mg/L), emphasizing the influence of human activities (e.g., cooking) on the emission of volatile and semi-volatile organic compounds in the air, which consequently reside in harvested water. Aldehydes and volatile fatty acids (formate, acetate) comprised roughly 50 % of the DOC found in the AWE water. A carbon fiber filter was not effective at removing these substances, highlighting the need for further research into effective treatment methods for DOC management before the safe use of AWE water. Overall, this study provides critical insights for the practical application of indoor SAWH as a decentralized source of high-quality water and emphasizes the need to identify and manage DOC for its safe use.

Water quality constraints H2O2 production in a dual-fiber photocatalytic reactor

In-situ hydrogen peroxide (H2O2) finds applications in disinfection and oxidation processes. Photoproduction of H2O2 from water and oxygen, avoids reliance upon organic chemicals, and potentially enables smaller-sized or lower-cost reactors than electrochemical methods. In ultrapure water, we previously demonstrated a novel dual-fiber system coupling a light emitting diode (LED) with a metal-organic framework (MOF) catalyst-coated optical fiber (POF-MIL-101(Fe)) and O2-based hollow-membrane fibers and achieved a remarkable H2O2 yield, 308 ± 1.4 mM h-1 catalyst-g-1. To enable H2O2 production anywhere we sought to understand the impacts of common water quality parameters. The production of H2O2 was not affected by added sodium, potassium, hydroxide, sulfate or nitrate ions. There was consistent performance over a wide pH range (4-10), maintaining a high production rate of 232 ± 3.5 mM h-1 catalyst-g-1 even at pH 10, a condition typically unfavorable for H2O2 photoproduction. Chloride ions produced hypochlorous acid, consuming in-situ produced H2O2. Phosphate adsorption on the iron-based MOF catalysts blocked H2O2 production. Inorganic carbon species inhibited H2O2 production due to in-situ formic acid. Encouraging results were obtained using atmospheric water (i.e., condensate), with rates reaching 288 ± 6.1 mM h-1 catalyst-g-1, comparable to ultrapure water. This underscores atmospheric water as a variable alternative, available in nearly all building air conditioning systems or could overcome geographical constraints, particularly in regions where obtaining pure water resources is challenging, offering a cost-effective solution. The dual-fiber reactor using atmospheric water enables high-efficiency H2O2 production anytime and anywhere.

Techno-Economic Analysis of Atmospheric Water Harvesting Across Climates

Drinking water scarcity is a global challenge as groundwater and surface water availability diminishes. The atmosphere is an alternative freshwater reservoir that has universal availability and could be harvested as drinking water. In order to effectively perform atmospheric water harvesting (AWH), we need to (1) understand how different climate regions (e.g., arid, temperate, and tropical) drive the amount of water that can be harvested and (2) determine the cost to purchase, operate, and power AWH. This research pairs thermodynamics with techno-economic analysis to calculate the water productivity and cost breakdown of a representative condensation-based AWH unit with water treatment. We calculate the monthly and annual levelized cost of water from AWH as a function of climate and power source (grid electricity vs renewable energy from solar photovoltaics (PV)). In our modeled unit, AWH can provide 1744-2710 L/month in a tropical climate, 394-1983 L/month in a temperate climate, and 37-1470 L/month in an arid climate. The levelized cost of water of AWH powered by the electrical grid is $0.06/L in a tropical climate, $0.09/L in a temperate climate, and $0.17/L in an arid climate. If off-grid solar PV was purchased at the time of purchasing the AWH unit to power the AWH, the costs increase to $0.40/L in an arid climate, $0.17/L in a temperate climate, and $0.10/L in a tropical climate. However, if using existing solar PV there are potential cost reductions of 4.25-5-fold between purchasing and using existing solar PV, and 2-3-fold between using the electrical grid and existing solar PV, with the highest cost reductions occurring in the tropical climate. Using existing solar PV, the levelized cost of AWH is $0.09/L in an arid climate, $0.04/L in a temperate climate, and $0.02/L in a tropical climate.

Solar-off-grid atmospheric water harvesting system: Performance analysis and evaluation in diverse climate conditions

Global warming, climate change, and conflicts have collectively exacerbated the pressing issue of water scarcity on a global scale. Addressing this critical challenge and ensuring equitable access to water for all necessitates a heightened commitment and the introduction of groundbreaking initiatives. In light of the growing global awareness surrounding this issue, this study introduces an innovative, grid-independent, solar-powered approach to atmospheric water harvesting. The simulations yield valuable insights that can serve as a foundation for further investigations by fellow researchers. Central to this study is the exploration and examination of the influence of dew point temperature, a pivotal factor in condensing atmospheric water, as it shapes the water collection process. The credibility of the results is reinforced through meticulous cross-referencing with existing literature, following extensive exploration and analysis of various parameters. The study's adaptability is put to the test across three distinct climatic locations: a coastal, a typical, and a desert environment. In desert conditions, the system achieves an average daily water collection of 45 l, while in coastal climates, this figure escalates to an impressive 100 ll per day. Remarkably, July emerges as the most prolific month for water collection across all simulated regions. To comprehensively evaluate the system's efficiency in capturing water vapor, a comparative analysis is conducted against alternative designs. The proposed approach excels in terms of water harvested per kilowatt of energy consumed, boasting values of 3.248 kg/kWh, 2.689 kg/kWh, and 1.871 kg/kWh for coastal, typical, and desert regions, respectively. Notably, the coastal area stands out as the most effective, owing to its consistently hot and humid climate. With similar meteorological conditions in place, this system holds the potential for global replication, facilitating the collection of water volumes comparable to those observed in coastal regions.

Water harvesting on biomimetic material inspired by bettles

Many organisms in nature such as beetles and cacti can survive in arid places by their own surface structures that are still able to collect mist. These surfaces have micro-nano structures that maintain a very low adhesion, allowing them to continuously collect and transport water. Here, we used a light curing three dimensional molding process to create a template for a water harvesting system inspired by the back of a beetle, a hydrogel-like beetle back surface for water transport. By changing the curvature structure of the water evacuation channels and altering the hydrophilic and hydrophobic properties of the surface, the designed large-scale artificial water harvesting study was made possible. The results show that if the surface has a proper curvature structure and hydrophobic density, the water collection on the super-impregnated surface is much higher than that on an ordinary hydrophobic surface. Based on this, a new efficient and environmentally friendly water collection scheme is proposed. The data show that the triangular tip structure imitating beetle-backed hydrogel surface collects the highest amount of water with a water weight of 16 g in 2 h. This study offers interesting prospects for designing a new generation of structural materials with a bionic structure distribution for high-efficiency water harvesting. The results of the study are useful for pushing the improvement of environmental-friendly water collection, transport and separation devices.

Abbreviations

The dorsal shape of the beetle's back is critical for water collection. In this work, while redesigning the shape of the back of the beetle, the method of 3D printing the beetle back template was used to prepare the beetle back made of hydrogel, which greatly improved the water collection performance and has certain engineering application prospects.