Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 07 July 2011
By Kristin Palitza
South African scientists have developed an environmentally friendly method to clean highly toxic water and convert it into drinkable water. Once available commercially, the method could drastically reduce the negative impact industry has on water pollution worldwide.
Called eutectic freeze crystallisation, the technique freezes acidic water – or brine – to produce potable or drinking water as well as useful salts, such as sodium and calcium sulphate.
Alison Lewis, professor for chemical engineering at the University of Cape Town in South Africa, who has led the research since 2007, claims 99.9 percent of the polluted water can be reused after applying the new technique. Unlike other water cleaning methods, it practically doesn’t produce any toxic waste.
“It’s an environmentally friendly and cost-effective technology that can be used pretty much in all industrial sectors that pollute water and thus produce brine,” explains Lewis. This includes sectors like mining, the oil and gas industry, chemical industry, paper processing or sewerage.
The simultaneous separation and purification method is based on bringing the contaminated water temperature down to reach its eutectic point – the lowest possible temperature of solidification. At this point, toxins crystallise to form salts and sink to the ground, while the clean water turns into ice, floating on the surface.
“By its nature, ice is the purest form of water because it repels any impurities. It’s actually very simple,” explains Lewis. “The method is ecologically significant because it can turn toxic waste into a useful product.” Continue reading