Constant access to a supply of freshwater is critical for life on this planet, as well as for the growth of industry, agriculture and modern-day economies. But natural water supplies are depleting in many parts of the world, with around 2.2 billion people lacking safely managed drinking water, according to United Nations estimates.

Many countries rely on converting ocean water into freshwater using desalination plants. But the reverse osmosis and thermal distillation techniques currently used are energy intensive and leave behind brine that raises the salt level of the water (and reduces oxygen levels), which can harm sea life.

Researchers from the University of Rochester have taken a new approach by developing a solar-thermal desalination process that’s less energy intensive, doesn’t generate brine and doesn’t require chemical additives to pre-treat the water.

“Today, about one quarter of the global population lacks safely managed drinking water; but at the same time the oceans contain an enormous resource of both water and valuable minerals,” explains lead researcher Chunlei Guo. “We wanted to develop a technology that could address these challenges together, producing freshwater sustainably while turning what is traditionally considered waste into a resource.”

The novel desalination technology, described in Light: Science & Applications, is based on a multi-functional superwicking black metal (SWBM) panel created via femtosecond laser processing. Desalination involves evaporating and distilling the water, removing the salt in the process. To do this, materials that absorb sunlight and heat up, while wicking water, are required. The SWBM panel proved effective at both.

The SWBM panel is highly attractive to water and can pull a thin film of water upwards across its surface, while absorbing almost all solar energy. This uphill pulling of water against gravity means that the panel can be placed in any orientation, enabling effective solar tracking.

The evaporated and distilled water can be extracted from the panel and the remaining salts are directed away from the panel’s active region and deposited in its passive (untreated) regions. This not only self-cleans the active region of the panel, but enables continuous desalination to produce distilled drinking water.

Harvesting valuable minerals

This approach means that concentrated brines are not deposited back into the ocean, and the solid salt can be collected and used to produce common table salt. The process also extracts other precious minerals such as lithium, which could be used in battery manufacturing. As traditional land-based mining becomes more expensive, extracting lithium directly from ocean water could prove a lower-cost, more sustainable option.

“The most important advance is that our system can desalinate real ocean water continuously using sunlight alone, without generating waste, with little to no maintenance and while recovering valuable minerals such as lithium,” says Guo. “By using a superwicking, self‑cleaning surface invented in my lab to move salts away from the evaporation region, we overcame the clogging bottleneck that has limited solar desalination until now. This is the first time we have achieved stable, low‑maintenance, high‑efficiency and nearly 100% salt-recovery performance with actual seawater.”

The self-cleaning mechanism is vital for use in real-world scenarios. Many desalination technologies work in the lab where the only mineral component is sodium chloride. Ocean water, however, contains many other materials, such as magnesium and calcium salts, that could crystallize on the panel and clog it. The self-cleaning process is driven by etched grooves that stop these minerals from staying on the panel. If oceans contain too high a mineral content, wider and deeper grooves can be etched into the panel by applying a higher laser power during fabrication.

The team tested the solar-thermal desalination panel using water samples from Pacific, Atlantic and Indian Oceans. When tracking the sun over a week to purify the ocean water, the panel demonstrated an average evaporation rate of 1.76±0.04 kg/m²/h and a salt harvesting rate of 61.74 ± 2.46  kg/m²/h under one sun illumination, corresponding to 74% solar-to-vapour conversion efficiency and near-100% salt extraction.

The researchers are now working to scale up the technology and integrate it with other mature platforms, such as solar cells. “We have made significant progress by demonstrating that the desalination process can be used to cool the solar cells, improving electrical output while simultaneously producing freshwater. This approach could lead to a synergistic water-energy system that operates sustainably,” Guo tells Physics World.

The post Solar-thermal desalination process operates at near 100% efficiency appeared first on Physics World.

A remarkable discovery has been made in East Africa’s Lake Malawi, one of the deepest bodies of water on the African continent.

Africa’s impressive lakes have long remained a focus of speculation for naturalists, involving folklore about strange creatures—including supposed holdovers from prehistoric times—alleged to inhabit some of their waters.

However, a much smaller discovery made by a team of researchers with the Department of Zoology at the University of British Columbia (UBC) at Vancouver, Canada, is nonetheless challenging our past thinking on what kinds of life forms can be found lurking in the depths of some of Africa’s storied lakes.

In a remarkable discovery, a variety of lake fly larvae have been found descending into the very oxygen-deprived depths of Lake Malawi, where they hide more than 650 feet below the surface to avoid predators.

After spending their days in this deep-water “dead zone,” the larvae reemerge at night and feed—or at least some of them do, if they are lucky enough to escape the fish searching for a dinner of their own, while these tiny insects are commuting back to the surface.

A Surprising Discovery Deep in Lake Malawi

To chart the unusual daily cycle of these larvae, UBC researchers Dr. Philip Matthews and Dr. Evan McKenzie used sonar technologies, which were positioned deep within the lake.

While this provided an idea about where these tiny insects were going, it was dissecting the larvae that revealed how these remarkable little creatures have somehow evolved a respiratory system that contains two pairs of small air sacs, which function like ballast tanks, allowing the larvae to control their buoyancy.

Within these sacs, they discovered the presence of resilin, a material that can either expand or contract in proportion to changes in the pH of the sac’s walls. As a result, the larvae can change the volume of these unique air sacs, thereby controlling their buoyancy.

It is an unusual capability these creatures display, to say the least. Curious about how deep they might be able to go, the researchers placed several of the larvae within small pressure chambers to simulate the depths they might travel to before the sacs imploded.

Much to the team’s surprise, these natural buoyancy systems held out under conditions that would match depths of 400 meters (1,312 feet), which is much deeper than what the sonar data reveals about the larvae’s daily descents into Lake Malawi.

While it has long been assumed that insects, which often thrive in freshwater environments, do not live in open oceans due to such pressures associated with the depths of the world’s largest bodies of water, these African insect larvae reveal that such creatures can survive under such conditions.

Based on their findings, the UBC researchers hope to work on finding ways of simulating such capabilities, perhaps by creating pH-powered resilin smart materials, or even artificial systems that emulate the way muscles operate.

The team’s findings appeared in the new study, “Crush-resistant air sacs allow insect larvae to exploit aquatic habitats at extreme depth,” published in the journal Science.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

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The post There’s One Very Stinky Reason Why Labour’s Housebuilding Targets Are Doomed to Fail appeared first on The Daily Sceptic.

Water and spice influenced eating in opposite and unexpected ways during controlled meal experiments. A glass of water beside a meal is often treated as an easy way to eat less. The usual explanation is that the water stretches the stomach and creates a sense of fullness before too much food is consumed. A Cornell [...]

A new review of previous studies in the journal Appetite undercuts the popular belief that water fills you up at the table.

The post Researchers Challenge Long-Held Beliefs about Water, Spicy Food and Digestion appeared first on Sci.News: Breaking Science News.