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Wastewater a key resource for agriculture - FAO rep

Published:Thursday | December 12, 2013 | 12:00 AM

Petre Williams-Raynor, Contributing Editor

WHILE NOT without risk, wastewater presents one of the best options for helping to ensure food security in the Caribbean.

And given current economic realities, it is an option the region should not overlook, says Lystra Fletcher-Paul, the United Nations Food and Agriculture Organisation (FAO) representative in Guyana.

"In most countries, agriculture is the main user of water ... . But in most countries, it is not available, and so they have to use other sources - not just the rainfall or the rivers," she said, speaking at a recent training workshop for journalists, hosted by the Caribbean Regional Wastewater Management Fund.

"In a number of countries, they are talking about rainwater harvesting. But in some parts of the countries where there is not enough rainfall, you have to look at other sources of water, and this is where wastewater reuse and recycling comes in," Fletcher-Paul noted.

There are any number of ways to make wastewater - water that contains waste from residential, commercial and/or industrial use - work for agriculture.

"It can be used in aquaculture. In parts of China, wastewater has been used in growing fish ... . It is also used on vegetables for human consumption. When next you see water chestnuts in a Chinese restaurant, think of it, it may have been grown on wastewater. Duckweed, which is cultivated mainly for fish feed, is also used for feeding chickens, which we eat," Fletcher-Paul revealed.

The benefits of wastewater use, she said, are many, not the least of which is that "you would have a constant availability of water".


"Wastewater also has nutrients that plants need - like nitrogen, phosphorous [and] potassium. So there is nutrients in the water that can be used in the soil, and those nutrients are recycled and as a result you get less pollution in your water bodies," she said.

However, things are not all 'peaches and cream' when it comes to wastewater reuse and recycling.

"There are [in wastewater] pathogens, heavy metals, toxic organic compounds, salts, and there is a risk to human health. There is [also] a risk to the environment and crop productivity," Fletcher-Paul said.

But the risks can be managed, she maintained.

One can, for example, opt to use wastewater on long-stemmed plants instead of short-stemmed plants.

"In other words, if your wastewater is on the ground, you take the plants with longer stems and plant them so that there is less chance of contamination of your leaves, etc," Fletcher-Paul said. "You can [also] decide that you are not going to use very polluted water on things like lettuce and tomatoes and pak choi, where the leaves are what you consume."

One can also use a drip-irrigation system, which "applies the water simply to the roots [of the crops] rather than a sprinkler irrigation, which sprinkles all the water and disperses all the pathogens into the atmosphere".

"And you can decide, if you know this fruit or this vegetable has been irrigated with recycled water, to cook the food or use chlorine or anything to disinfect, which will then kill the bacteria and make food healthy," the FAO rep said.

Further, farmers should use protective gear and water quality tested.

"Taking measurements of water quality is important because it can then tell you whether that water can be applied to plants like lettuce and pak choi, and so on," Fletcher-Paul said.

The use of small-scale technologies, such as sand filters, is also encouraged to purify wastewater for reuse.

Beyond that, it is necessary to do research to support efforts for wastewater use in agriculture and to put in place supporting policies, legislation and incentives.

"You can introduce subsidies or taxes for environmental services, which will encourage safe practices. But instead of using the stick, use the carrot. So if a company or a farmer uses a particularly type of technology that promotes the safe use of rainwater, let's give that person a tax break which will encourage the use of wastewater recycling," she said. "And, of course, education and social awareness, especially in terms of your communications campaign and the impact of public perception, [is also critical]."