Freezing technology can be utilised in waste water treatment. When waste water freezes, it is purified through the formation of a cleaner layer of ice. The clean layer of ice can be removed from the rest of the waste water, and the remaining waste water is more concentrated.

The new energy-efficient method of purification is based on the natural freezing process of water: energy is required only for breaking the ice and transporting it from the waste water pool.

In practice, this method could be used by leaving waste water from mines to freeze in special pools under the open sky, after which the cleaner part could be removed by breaking the ice. After that the ice would be taken away using a machine designed for that purpose to another pool where the treated waste water would be recycled, or undergo further treatment using membrane filtration, for example, for the needs of various processes. Recycling water from the industrial process would reduce the amount of fresh water that is used. Read more

Scientists at the University of Rochester have used lasers to transform metals into extremely water repellent, or super-hydrophobic, materials without the need for temporary coatings.

University of Rochester’s Institute of Optics Professor Chunlei Guo has developed a technique that uses lasers to render materials hydrophobic, illustrated in this image of a water droplet bouncing off a treated sample. Credit: J. Adam Fenster/University of Rochester

Super-hydrophobic materials are desirable for a number of applications such as rust prevention, anti-icing, or even in sanitation uses. However, as Rochester’s Chunlei Guo explains, most current hydrophobic materials rely on chemical coatings.

In a paper published today in the Journal of Applied Physics, Guo and his colleague at the University’s Institute of Optics, Anatoliy Vorobyev, describe a powerful and precise laser-patterning technique that creates an intricate pattern of micro- and nanoscale structures to give the metals their new properties. This work builds on earlier research by the team in which they used a similar laser-patterning technique that turned metals black. Guo states that using this technique they can create multifunctional surfaces that are not only super-hydrophobic but also highly-absorbent optically. Read more

In June the state of Florida made an unusual announcement: it would sue the U.S. Army Corps of Engineers over the corps’s plan to reduce water flow from reservoirs in Georgia into the Apalachicola River, which runs through Florida from the Georgia-Alabama border.

Water is needed to generate energy. Energy is needed to deliver water. Both resources are limiting the other—and both may be running short. Is there a way out?

Florida was concerned that the restricted flow would threaten certain endangered species. Alabama also objected, worried about another species: nuclear power plants, which use enormous quantities of water, usually drawn from rivers and lakes, to cool their big reactors. The reduced flow raised the specter that the Farley Nuclear Plant near Dothan, Ala., would need to shut down.

Georgia wanted to keep its water for good reason: a year earlier various rivers dropped so low that the drought-stricken state was within a few weeks of shutting down its own nuclear plants. Conditions had become so dire that by this past January one of the state’s legislators suggested that Georgia move its upper border a mile farther north to annex freshwater resources in Tennessee, pointing to an allegedly faulty border survey from 1818. Read more

Chuck Wight, a chemistry professor at the University of Utah, provides the following explanation:A typical water-softening system removes calcium and magnesium ions from hard water and replaces them with sodium ions. Calcium and magnesium ions interfere with the action of household soaps and detergents, but sodium does not.

The water-softening process thus helps detergents to more effectively remove dirt and oils from clothing and dishes. It also helps soaps to give a “slippery” feel to your skin when you wash. Most manufacturers of water softeners recommend that you reduce the amount of soap and detergents you use after installing a water softener. Read more