Wastewater use in irrigated agriculture
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Springer Science+Business Media B.V. 2010Wastewater irrigation is a widespread phenomenon. Although its main drivers differbetween regions and along the sanitation ladder, they clearly indicate that the practicewill continue to increase. This is especially the case in low-income countries wherefarmers in the economically interesting peri-urban interface are hardly able to findunpolluted surface water sources, as a result of inadequate wastewater collection andtreatment. In other countries, reuse of (usually treated) wastewater is an importantstrategy to cope with fresh water scarcity. Both water scarcity and the gap betweenpopulation growth and investments in sanitation will without question continue tochallenge us in years to come.At present, more than 80% of the sewage generated in developing countries isdischarged untreated into the environment, and about 50% of the population depends onpolluted water sources for various uses, including irrigation (UNESCO2003).Global estimates of the total irrigated area under raw and diluted wastewater arestill fragmentary, but are likely to range between 5 and 20 million hectares, with thelargest share probably in China due to its severe water pollution problems. Poorwastewater treatment and resulting large scale water pollution also suggest that theshare of area irrigated with unsafe wastewater is probably ten times larger than thearea using treated wastewater (Scott et al.2010). However, estimates are stillrudimentary and much more work is required to fully understand the extent of thisproblem and its implications. The same applies to the affected population. Nearly twodecades ago, Paul Lunven estimated that at least 10% of the world’s population consumesfood irrigated with wastewater (WHO2006). Current estimates point at roughly onebillion consumers of agricultural products initially grown with wastewater. A part of thisgroup consumes raw produce, such as salad greens. In developing countries, theseconsumers face the most severe health risks, as only a small percentage of the wastewater
undergoes sufficient treatmen
