A membrane is really a filter and, hence, prone to clogging. To overcome this in reverse-osmosis systems, water is allowed to cross-flow across the membrane, so that some water gets to the other side and the rest flushes out the accumulated by-particles such as salts. Since such a system allows only partial recovery of drinking water from seawater, RO plants use an array of membranes, so that water flowing from one membrane becomes the feed for the next. However, even this is a problem because it is difficult to balance flow rates across all membranes.
To overcome this, DuPont (through its brand DesaliTec) has come up with a solution it calls ‘closed-circuit reverse-osmosis’ (CCRO). DuPont Water Solutions’ Commercial Leader-Pacific, Tanmeet Gulati, told Quantum that while conventional RO plants rely on sequential membrane arrays, CCRO recycles a given batch of water through a single membrane array “until no further recovery is possible”. Literature provided by the company says that “at a software-based set point, the system automatically flushes out all the concentrate and then returns to operation mode. The flush is automatically triggered by the software in response to set points that include recovery, pressure, permeate quality and other water quality parameters”.
The result is a high recovery rate, which can, in turn, help reduce cost of water produced.
Powerless heating
Dr Sumer Singh of the Department of Design, IIT-Delhi, and his team have come up with a low-cost heating system that can be activated by plain water anytime, anywhere and does not require any fuel or electricity to heat or power it. It can provide low-grade heating in any location.
Singh calls it ‘powerless heating technology’. It is particularly useful in remote places.
The active heating element consists of a mixture of eco-friendly minerals and salts, which generate exothermic energy, resulting in heat on contact with water. This provides enough energy to raise the temperature of any food or beverage by 60-70 degrees Celsius. The heater weighs only 50 g, and after every heating the by-product (natural mineral rock) inside the heating pad can be disposed of. The rock helps improve soil fertility and is biodegradable.
With this technology, users can heat ready-to-eat food, and make instant noodles and beverages like tea and coffee.
The release says that ITC Ltd has come forward to use the technology.
North East Centre for Technology Application and Reach (NECTAR), an autonomous body under the Department of Science and Technology, supported Dr Singh and his team to develop a food box and a liquid container that can be integrated with the powerless heating technology.
Staggeringly tough
The toughest material in the world today is an alloy made of chromium, cobalt and nickel (CrCoNi).
CrCoNi is a subset of a class of metals called high entropy alloys (HEAs). All the alloys in use today contain a high proportion of one element with lower amounts of additional elements added, but HEAs are made of an equal mix of each constituent element. These balanced atomic recipes bestows some of these materials with an extraordinarily high combination of strength and ductility when stressed, which together make up what is termed “toughness.” HEAs have been a hot area of research since they were first developed about 20 years ago, says a press release from the Lawrence Berkeley National Laboratory, US. But the technology required to push the materials to their limits in extreme tests was not available until recently.
The toughness of this material near liquid helium temperatures (20 kelvin, -424 fahrenheit) is as high as 500 megapascals square root meters. In the same units, the toughness of a piece of silicon is one, whereas, the aluminium airframe in passenger airplanes is about 35, and the toughness of some of the best steels is around 100. “So, 500, it’s a staggering number,” the release says.