ROME, Italy - With food demand and water scarcity rising, it's time to stop treating wastewater like garbage and instead manage it as a resource that can be used to grow crops, according to the Food and Agriculture Organization of the United Nations (FAO).
Ahead of the World Water Day in March, which this year has a focus on water reuse, FAO has said that if properly managed, wastewater can be used safely to support crop production — directly through irrigation or indirectly by recharging aquifers.
Already, agriculture accounts for 70% of global freshwater withdrawals — with demand for food estimated to grow by at least 50% by 2050, agriculture's water needs are poised to expand.
A number of technologies and approaches exist that are being utilized around the globe to treat, manage, and use wastewater in agriculture, many of them specific to the local natural resource base, the farming systems in which they are being used, and the crops that are being produced.
In addition to helping cope with water scarcity, wastewater often has a high nutrient load, making it a good fertilizer.
In Egypt, for example, where water supplies are limited and wastewater tends to be highly contaminated, constructed wetlands are proving to be a promising, economically viable approach to treatment. In Tunisia wastewater is being widely used in agroforestry projects, supporting both wood production as well as anti-desertification efforts. In Jordan, reclaimed water represents 25% of all total water use in the country.
"Although more detailed data on the practice is lacking, we can say that, globally, only a small proportion of treated wastewater is being used for agriculture, most of it municipal wastewater. But increasing numbers of countries — Egypt, Jordan,, Mexico, Spain and the United States, for example — have been exploring the possibilities as they wrestle with mounting water scarcity," said Marlos De Souza, a senior officer with FAO's Land and Water Division.
"So far, the reuse of wastewater for irrigation has been most successful near cities, where it is widely available and usually free-of-charge or at low cost, and where there is a market for agricultural produce, including non-food crops. But the practice can be used in rural areas as well — indeed it has long been employed by many smallholder farmers.”
De Souza added: "When safely used and managed to avoid health and environmental risks, wastewater can be converted from a burden to an asset."