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Large Scale Water Purification Article

(Article courtesy Inter Press Service, Washington, DC)


By Susan Litherland

LONDON, July 14, 1995 (IPS) -- British researchers say a vegetable pod which grows on trees in Africa, Asia and Latin America may hold the key to solving a lot of the water problems in the developing world.

(Article courtesy Inter Press Service, Washington, DC)


By Susan Litherland

LONDON, July 14, 1995 (IPS) -- British researchers say a vegetable pod which grows on trees in Africa, Asia and Latin America may hold the key to solving a lot of the water problems in the developing world.

The team of researchers at the University of Leicester believe the vegetable pods, and the seeds they contain, can help to provide safe, cheaply produced drinking water that could save millions of people from disease or death, caused by impure drinking water.

About 1.3 billion people still lack safe drinking water and more than six million children die from diarrhea in developing countries every year.

According to the researchers, the tree on which the pods grow, the Moringa oleifera is common throughout Africa, Asia and Latin America. They also report that the tree is also a source of nutritious vegetables because the leaves and pods have a high protein content and are rich in vitamins.

But its potential as a water purification treatment has, until now, been almost totally overlooked.

The researchers have found that when the seeds are dried, crushed and added to water, the powder acts as a coagulant binding the particles and bacteria that make river water so murky, particularly during rainy seasons. After a short while the coagulated particles, known as floc, sink to the bottom and clear water can be poured off.

The $815,000 project is funded by the Overseas Development Administration (the British government's aid arm), and the Brussels-based European Commission. It works on the basis that opposites attract, explains Geoff Folkard, one of the British scientists involved in the four-year, research project.

"When mixed with water the crushed seeds produce positively charged proteins which attract the negatively charged particles and bacteria. The mixing action causes them to collide and stick to each other," he said.

Large water treatment centers do this by adding chemical coagulants to the water such as aluminum sulphate (alum), but in the developing world these are frequently unavailable or too expensive.

The team's experimental work at Thyolo in southern Malawi last year found the seeds gave purification results "just as good as those obtained with commercial chemicals" by removing 90 to 99.9 percent of the bacteria as well as clearing the water of solids.

While natural coagulants have been used for centuries at a household level in some parts of the world, such as Sudan and Indonesia, this is the first time they are being tried on a large scale and in continuous flow treatment.

In Malawi in 1993, imported chemicals from South Africa cost the Water Utilities more than $640,000 in valuable foreign exchange. Says Folkard, "The seeds do their job at a fraction of the cost.

Many countries could save huge amounts of money by adopting these ideas." Only two level teaspoons of crushed seeds are needed to treat a bucket of water (about 20 liters).

Mansoor Ali Lalani of the Water, Engineering and Development Center at the University of Loughborough is not so convinced. "I think that provided (sic) is produced locally and is available locally it remains a better alternative to Moringa. It creates larger flocs so the settlement is very quick."

And, he adds that depending on the water quality, less alum is needed per liter (35 milligrams compared with 150 milligrams of seed).

He does concede however that recent studies have indicated that alum residue in water may be carcinogenic, however, no harmful effects have been shown to come from Moringa.

Whether water is treated with conventional coagulants or the seeds, some harmful micro-organisms will remain which must be removed either by chlorination, simple sand filters, or in households by boiling.

The Moringa is a tough tree that survives in poor soils and uses its deep tap root to survive long periods of drought. Easy to propagate from seeds and cuttings, it grows rapidly to six meters in height and can flower and fruit in one year.

It seems to be a bit of a wonder plant because all parts are used in traditional medicines and the powdered seed is mixed with ointment to treat common bacterial skin infections.

It is also a good source of fuelwood and fodder for cattle and is suitable for agro-forestry because it does not throw heavy shade that prevents other crops from growing beneath its branches. Folkard is also confident that it can be easily controlled so that it does not become invasive and push out native flora.

But the benefits do not end there. The researchers are also looking at the tree's potential as a source of cooking oil. The seeds contain 40 percent of oil by weight and it gives a higher yield per hectare than either sunflower or ground nuts.

The team has also found that the dry residue left after pressing loses none of its coagulant properties. It can also be dried and stored for later water treatment as a low-cost by-product of extraction.

"Moringa oil is of high quality and has a high market value both for cooking and as the main ingredient in soap manufacture," points out Folkard. "The demand for oil in Malawi is greater than present production so soya bean oil is having to be imported from South America.

Which makes the cultivation of Moringa an attractive proposition for commercial farmers. In collaboration with Leicester, the Intermediate Technology Development Group (ITDG) of Zimbabwe has set up 17 small mills appropriate for small scale rural processing to test this idea.

It has concluded that the mills return an average of 51 percent on investment with profits of 21 percent on sales.

Zimbabwe's Plant Oil Producers Association has already expressed interest in trial plots. Says Folkard: "The Moringa is a classic example of the Third World producing what it does not consume and increasingly consuming what it does not produce."

The Leicester team are keen that small land holders also should be encouraged to grow the Moringa "as it will improve both their health and income." One tree would provide enough water treatment for five to six people for a year.

Finding out whether consumers will like the oil is future work for the ITDG, while in Kenya the Forestry Research Institute will look into Moringa tree management. For his part Folkard intends pushing ahead with implementation studies, possibly in Brazil, Tanzania and Zimbabwe.

A better supply of water for thirsty people in the Third World rests on the final outcome. Richard Carter of the water management department at Cranfield University states, "This is a project that commands our respect. We are sure it will be useful and relevant to the developing world."

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