Mexico: the sweet smell of success - What Price Water? - Cover Story

In Mexico's Jalisco State, a sugar mill has reduced its water consumption by four-fifths and cut its costs

The smell of burning sugar and the lengths of cut cane strewn along the dirt road point the way to the San Francisco Ameca sugar mill in Mexico's Jalisco state, the home of tequila, 73 kilometres from the city of Guadalajara. To the naked eye, the mill seems just like any other, with its tall chimneys, the sound of escaping steam and the comings and goings of its workers. Yet this factory stands apart. Until four years ago, the mill needed 15 litres of water to produce one kilogram of sugar. Now it uses only three litres.

Besides reducing production costs, this "miracle" is of direct benefit to the river Ameca, the mill's main source of supply and one of Jalisco's three largest rivers.

"We have made all these changes at the mill because we are convinced of the need to show concern for the water supply problem and also because water is becoming an increasingly expensive item," says chemist Matilde Osorio Cruz, head of the mill's manufacturing laboratory. In the space of five years, the price of water, a basic ingredient in sugar production, has risen fifteenfold.

An image of St. Francis is displayed near to the gates of the factory, which was founded in 1903. From that time until barely four years ago, sugar production required enormous amounts of water, which was drawn from the river Ameca. At the end of the process, most of the waste water was discharged back into the river and contaminated it. Unlike metals or other types of toxic chemical waste, the by-products of sugar, consisting chiefly of molasses, are eventually absorbed by the river but consume a considerable amount of oxygen, thereby depriving fish and plant life of sustenance.

According to Osorio, as a result of the measures taken this problem has been completely resolved. "The first thing we did was to set up a water treatment plant," she says. "Then we started to use closed circuits in which the water circulates continuously through the different parts of the process without any of it being lost, as used to be the case." In practical terms, the system devised is somewhat similar to that of the bloodstream, in which the fluid circulates and is processed without having to be renewed.

Closed circuits to prevent waste

Among the innovations introduced, Osorio cites the creation of a cooling tank to bring down the temperature of the water, which is very hot when it emerges from one part of the process, before using it again. The tank looks like an enormous fountain, since the system consists of a set of perforated pipes through which the water gushes before cooling in contact with the air. Thanks to the system, the water temperature is reduced from 45 [degrees] to 38 [degrees] C. Once the water has cooled, it is fed back into the system.

The project was made possible through support provided by the United Nations Industrial Development Organization (UNIDO), with the participation of Mexico's National Chamber of the Sugar and Alcohol Industry, the Group of Sugar-Exporting Countries of Latin America and the Caribbean (GEPLACEA) and the National Autonomous University of Mexico Similar systems are being used at the Motzorongo and El Potrero mills in the Mexican state of Veracruz.

The San Francisco mill is the pilot plant of the Beta San Miguel group, which owns a further four mills in Mexico, to which it plans to extend the water-conservation experience gained at Ameca.

According to information provided by UNIDO, its $493,000 loan to the mill could be recouped in two years as a result of cost savings. Sergio Miranda Cruz, the UNIDO official behind the technical studies culminating in this experiment, considers that "the results have been so positive that the project could develop into a full-scale programme. But quite frankly we have not yet reached that point."

The sugar-cane harvest started in November 1998 and will go on until May 1999. The machinery works night and day. The mill will produce some 100,000 tonnes of sugar and will consume 3,156 cubic metres of water per tonne produced. For the mill's technical staff and workers, optimizing water consumption and improving sugar quality present a difficult but rewarding challenge.

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