Editor’s pickIn the future, food may be grown with wastewater

28-12-2017

A woman tends to her crops. Image credit: Nana Kofi Acquah/International Water Management Institute

In a world that is increasingly afflicted with water scarcity, using recycled water is something that is both integrated and more and more normal. And in the future, using wastewater for agriculture to grow food may be inevitable.

Using wastewater for food production is mostly the issue of managing limited water resources and socioeconomic costs. A booming global population and climate change have put available water resources in jeopardy in many parts of the world, including Africa, Southeast Asia, and the Middle East. And it is now crucial that local communities find and implement solutions to resolve the issue of water scarcity.

According to Our World magazine by the United Nations University, if used well, wastewater can provide plants with important nutrients, replacing some fertilisers. But wastewater should only be used in agriculture after treatment. However, in many regions, the wastewater used has not been treated, and more is needed to be done in order to safeguard communities against the hazards of using untreated wastewater for agriculture.

Policies regarding water and agriculture do not adequately address the fundamental and inherent hazards untreated wastewater pose to irrigation – frequently in the form of bacteria that is resistant to antibiotics, heavy metal particles, organic contaminants, and pathogens. These then accumulate in the crops, soil, and even groundwater, and slowly passing into the food chain.

But using untreated wastewater has a huge advantage, especially in developing countries: Wastewater is free. Thus, farmers can use it to irrigate their crops without extra cost.

Legally used wastewater is presently irrigating between 1.5 per cent and 6.6 per cent of farmland around the world, and an estimated ten per cent of food produced is done with wastewater. But on the other hand, the full extent of untreated wastewater that is being used illegally for the production of food is unknown.

And the Mezquital Valley in Mexico is one of the best examples of showing the issues involved in using untreated wastewater for agriculture. Inadequate water treatment facilities combined with rapid urbanisation have resulted in farmers in the area turning to untreated and contaminated wastewater from the nearby Mexico City to irrigate their crops. And for more than a hundred years, the wastewater helped them produce marketable crops at low cost.

But the true cost came at the expense of the population’s health. The untreated water used on the crops manifested in the form of kidney cancer and severe gastrointestinal disease – Giarda infections – in the local community, and put the elderly, pregnant women, young children, infants, and others with compromised immune systems at a far more vulnerable position.

Since 1999, the Mezquital Valley has built local wastewater plants and added new wetlands to improve water quality. But despite all this, the residents of the valley are still sceptical of the benefits of using treated wastewater – and understandably so.

But even industrialised nations are struggling to address all the risks involved in using wastewater. For instance, bacteria resistant to antibiotics and emerging pollutants have been known to slip past conventional methods of wastewater treatment. However, even at low levels, the contaminants in questions still present a serious threat to human health.

While there is no running from the fact that food in the future will most likely be grown and cultivated with wastewater, especially with the current water situation in the world, protection is crucial. Government policies and regulations have to be evaluated and studied alongside scientific evidence regarding the hazards wastewater can pose to human health. Only then can wastewater be safely used in agriculture to drive sustainable development in this water-scarce world.

 

Source: Our World magazine by the United Nations University