Water, Sewage & Effluent November December 2018 | Page 35

4 Sand purification Sand and gravel have been used to purify water for thousands of years, and in 1804, a Scotsman named John Gibb designed and built the first filter that strained water through grains of sand to remove bigger particles of contamination. But recently, researchers have figured out how to coat sand grains with graphite oxide to create ‘super sand’ that reportedly can filter harmful substances such as mercury from water five times as effectively as ordinary sand. Work continues to find ways to make super sand absorb even more contamination and eventually use it in developing countries where water supplies are dangerously polluted. Sand, long used for filtration, is about to be boosted into ‘super sand’. The Atlas uses the best-available data to create high-resolution, customisable global maps of water risk. (Image for illustrative purposes.) www.waterafrica.co.za Water Sewage & Effluent November/December 2018 33 innovations Aqueduct's global water risk mapping tool helps companies, investors, governments, and other users understand where and how water risks and opportunities are emerging worldwide. The Atlas uses a robust, peer-reviewed methodology and the best-available data to create high- resolution, customisable global maps of water risk. Water scarcity is one of the defining issues of the 21st century. In its Global Risks 2013 report, the World Economic Forum identified water supply crises as one of the highest impacts and most-likely risks facing the planet. With the support of a diverse group of partners, the World Resources Institute built Aqueduct to help companies, investors, governments, and communities better understand where and how water risks are emerging around the world. Aqueduct water risk atlas 5