The National Academy of Engineering (NAE) announced today the winners of the 2007 Grainger Challenge Prize for Sustainability. The contest sought innovative solutions for removing arsenic from drinking water that is slowly poisoning tens of millions of people in developing countries. Three prizes will be awarded from a field of more than 70 entries.
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The Gold Award-winning SONO filter is a point-of-use method for removing arsenic from drinking water. A top bucket is filled with locally available coarse river sand and a composite iron matrix (CIM). The sand filters coarse particles and imparts mechanical stability, while the CIM removes inorganic arsenic. The water then flows into a second bucket where it again filters through coarse river sand, then wood charcoal to remove organics, and finally through fine river sand and wet brick chips to remove fine particles and stabilize water flow. The SONO filter is now manufactured and used in Bangladesh.

The system developed by the Silver Award-winning team is applied at a community’s well head. Each arsenic removal unit serves about 300 households. Water is hand-pumped into a fixed-bed column, where it passes through activated alumina or hybrid anion exchanger (HAIX) to remove the arsenic. After passing through a chamber of graded gravel to remove particulates, the water is ready to drink. This system has been used in 160 locations in West Bengal, India. The water treatment units, including the activated alumina sorbent, are being manufactured in India, and villagers are responsible for their upkeep and day-to-day operation. The active media are regenerated for re-use, and arsenic-laden sludge is contained in an environmentally safe manner with minimum leaching.