GEF

Unit 5  |  Toward Sustainable Water Systems 125 semiconductor plant uses between 2-4 million gallons of this ultrapure water every day, equivalent to the amount that is used by a small city. In order to cut down on this intensive water use, researchers from a sustainable engineering lab based at the University of Arizona have developed a sensor that immediately stops rinsing the moment the silicon wafers are sufficiently clean. Using these sensors in a typical semiconductor plant saves a significant amount of water, reducing waste and the amount of cleaning chemicals that end up in the environment. Because producing the ultrapure water is very expensive, the sensors also save money. The production of the silicon wafers used in electronics is extremely water-intensive. Many other businesses are becoming leaders in water sustain- ability. Unilever is the world’s third-largest consumer goods company, with a wide range of food, beverage, and personal care product brands. In the early 1990s, the company carried out an extensive environmental footprint study and recognized