Correspondents' Correspondence Reverse Osmosis

...Correspondents' Correspondence BRIEF TAKEOUTS OF MORE THAN PERSONAL INTEREST FROM LETTERS AND OTHER COMMUNICATIONS RECEIVED BY THE EDITORS Reverse Osmosis Geneva-Mankind's long-cherished dream of obtaining vast quantities of fresh, inexpensive water from the sea is closer to becoming a reality Reverse osmosis, a technique borrowed from nature and applied over the past decade and a half by engineers, is beginning to bear fruit And in the Mideast, steps have been taken to quicken the trend Universal access to clean water and sanitation would substantially reduce the burden of disease in the world's poorer regions, where about 80 per cent of all illness can be traced to an inadequate water supply Making the sea potable would stimulate food production, enhance industrial growth and end some of the drudgery in the lives of women and children who daily walk several miles to remote, unsafe wells It is hoped that achievement of this goal will be accelerated by an agreement for collaboration recently reached between the University of Toronto and the King Sand University in Riyadh The live-year, multimillion dollar accord, which also covers several other technologies, calls for joint research, the training of Saudi students in Canada, and the dispatch of Canadian professors to Saudi Arabia to inaugurate postgraduate training as well as further experimentation "This is the most developed relationship I am aware of between the Saudis and any North American university," says Dean Gordon Slemon of the Canadian school's Engineering and Applied Science Department Saudi Arabia has provided the financing The desert Kingdom already relies heavily on desalination At present there are 20 operational plants according to the Arab League Educational, Scientific and Cultural Organization, by the turn of the century the number will be increased by 50 Some of the facilities will be constructed aboard ships that can serve several areas as the need arises, creating huge stores of water for consumption in one spot before moving on The traditional approach to purifying, distillation, requires a daunting expenditure ot energy Still employed on a large scale, it is viable only for the richest of the rich The new reverse osmosis system, by contrast, needs about half the power to generate the same output Used by fish, it involves reversing the usual direction of liquids flowing through a membrane The most modern water treatment plants deploy millions of hair-thin tubes composed of man-made materials for filters Sea water molecules are forced through these capillaries at pressures of hundreds of kilograms per square centimeter The dissolved solids in the water are simply left behind Advances in membrane design and engineering methods-an objective of the Toronto-Riyadh effort and similar projects-are expected to reduce the energy requirement by half again Reverse osmosis plants can be built in around half the space and two thirds of the time it takes to erect comparable distillation plants, too At present the process remains expensive, though It requires heavy initial capital investment and an operating cost of around $4 per 1,000 gallons of water Application has therefore been limited to profitable agribusinesses and the large cities of the wealthy world But further innovations are likely to bring the price within range of even the poorest communities Moreover, reverse osmosis is not limited to sea water, it can be used to purify water of various materials besides salts This flexibility promises to be a boon in industrial areas where ground water has been contaminated, whether by pollution or by natural sources Plants are already being installed around the world for many purposes One in Algeria is serving a paper mill, another in the USSR is part of a Caspian Sea energy complex, and a third in Venezuela is harnessed to an energy undertaking Several installations going up in Europe, Australia and North America are to aid in agriculture and environment modification A spokesman for an Arabian Gulf nation summed up the spirit behind the Saudi-Canadian project during a recent UN debate "The world possesses the scientific and technological capacity to assure proper drinking water and sanitation facilities for every society-hence the close link between drinking water supply and sanitation on the one hand, and cooperation on (he other'-Thomas Land...