Engineers have developed a new wood-based steam generator that can purify water using bacteria-produced nanomaterials and the sun's energy.

Solar steam generators, which use the sun's energy to separate water molecules from contaminants via evaporation, aren't new, but the quest to make the technology as efficient as possible is never-ending.

When working to improve upon solar steam generators, scientists can focus one or more sources of inefficiencies: light absorption, heat management, water transport or evaporation.

Researchers at the University of Science and Technology of China developed a water purification device that improves on all four processes.

The team of scientists selected wood for its sustainability, and because its porosity allows for rapid water transport. To bind the device's wood layers, researchers relied on long cellulose nanofibers, which are produced by bacteria.

After sterilizing the wood, scientists applied the bacteria strain Gluconacetobacter xylinus and allowed it to ferment on the back of a block of wood. Next, researchers sprayed on a layer of aerosolized glass bubbles, an excellent insulator.

"The glass bubbles became embedded in the cellulose nanofibers produced by the bacteria, forming a hydrogel," researchers explained in a news release.

The cellulose nanofibers formed by the bacteria worked to bind together layers of the device together. To complete the device's light absorbing top layer, researchers applied carbon nanotubes, which became intertwined with the cellulose nanofibers.

The device -- detailed Wednesday in the journal Nano Letters -- works by pulling and filtering water up throw the wood layers to the light absorbing top layer, which is heated by the sun. The purified water evaporates and is collected and condensed above and funneled to a holding tank.

The carbon nanotubes and cellulose nanofibers lower the energy required for water vaporization, while the layer of glass bubbles ensure the sun's energy doesn't dissipate down through the wood layers.

In addition to being constructed using relatively cheap and sustainable materials, the device boasts a higher evaporation rate and greater efficiency than most current solar steam generators.

The simple technology could be used to purify seawater, as well as contaminated lake and river water, in remote locations and in parts of the developing world.

Climate change turning US mountain lakes green with algae
Paris (AFP) July 7, 2020 - Global warming is turning clear mountain lakes green in the western United States because of an increase in algae blooms "without historical precedent", researchers reported on Tuesday.

The concentration of algae in two remote mountain lakes more than doubled in the past 70 years, researchers at Colorado State University found.

Their results, published in the British Royal Society journal Proceedings B, highlight the potentially harmful effects of climate change on pristine and remote ecosystems.

"Even in relatively remote lakes located in protected areas... the fingerprint of human perturbation of Earth System is evident," lead researcher Isabella Oleksy of Colorado State University told AFP.

"Rapid warming of high elevation environments has resulted in the rapid acceleration and dominance of green algae, which until recently were found in low abundance in these lakes."

The team of scientists led by Oleksy examined algae concentrations in lakes in a mountain range about 100 kilometres (65 miles) from Denver, using a tool called a gravity corer to collect sediment cores without damaging the lakebed.

Drawing on measurements going back to the 1950s, they found "dramatic changes" in algal abundance in the form of green algal blooms called chlorophytes, which thrive in warmer temperatures.

The high level of algae "came as an ecological surprise", Oleksy said.

She noted that the amounts of algae documented in the study would more typically be found in highly polluted areas, such as those prone to agricultural run-off, and not in unsullied mountain environments.

"While we documented these changes in two lakes in Colorado, it is likely that this is not an isolated phenomenon," she said.

The results are not a smoking gun, the researchers acknowledged, but point to climate change as driving the excess accumulation of nutrients -- such as phosphorus and nitrogen -- that cause algal blooms.

In lakes and oceans, algae blooms sicken wildlife if ingested and destabilise aquatic environments by blocking out sunlight, the United States Environmental Protection Agency says on its website.

Fresh water and marine algae blooms have a huge negative economic impact, affecting fisheries, tourism and human health.

Related Links
Water News - Science, Technology and Politics

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Anammox bacteria generate energy from wastewater while taking a breath
Thuwal, Saudi Arabia (SPX) Jul 03, 2020
A type of anaerobic bacteria responsible for more than 50 percent of nitrogen loss from marine environments has been shown to use solid-state matter present outside their cells for respiration. The finding by KAUST researchers adds to knowledge of the global nitrogen cycle and has important energy-saving potential for wastewater treatment. Living organisms use oxidation/reduction reactions to harvest the energy they need for survival. This involves the transfer of electrons from an electron donor ... read more