Worth its salt?

摘要

THE SOREK desalination plant, about 15km south of Tel Aviv, is eerily unpopulated. This is the largest such plant in the world, producing as much as 230m cubic metres of desalinated water a year-about one-fifth of Israel's domestic water supply. Yet only 20 staff are needed at any time to operate it. Seawater is piped in from over a kilometre out at sea. It is given a preliminary clean in a series of large tanks where it is filtered slowly through sandbeds before being pumped through "reverse osmosis" membranes (pictured). These are based on a design first patented in the early 1960s by Sidney Loeb, an American scientist who moved to Israel and saw his invention eventually oust competing methods and become the dominant desalination technology not just in his new homeland, but around the world, accounting for 69% of the output of desalinated water. They certainly seem effective. The water is absolutely tasteless. Indeed, what it lacks-calcium and magnesium, for example-causes more worries than pollutants.