SUCCESS STORY: Where there's muck there's hope

Posted: 8 June 2004

Waste is a life and death issue in many parts of the world. Poor sanitation and rubbish collection, along with a poor water supply, play a big part in the deaths of some 1.8 million people, mostly children, who die from diarrhoea each year. According to the World Health Organisation more than a third of these deaths could be avoided if sanitation was improved. Now a couple of English professors believe they have found a way to deliver low cost solutions.

For Leeds civil engineering professors Ed Stentiford and Duncan Mara this is their life's work. And this year they are working on EU-funded projects in Vietnam, Thailand, Bangladesh, Nepal and Colombia helping to clean up towns and cities lacking the infrastructure that is often taken for granted.

The key in these cash-strapped economies is to sidestep high-tech solutions and use locally-available technology and resources, processing waste safely and recycling it or turning it into compost and producing irrigation water from sewage where possible.

These principles are illustrated by Professor Mara's specialism - low-cost sewers - which are currently being built in the city of Cali in Colombia.

He said: "Often engineers in developing countries want hi-tech water treatment systems, but these are high-cost too. They depend on unreliable electricity and equipment that can break down, needing expensive spares. We try to convince them that they should make the most of the resources they have to hand like cheap land, plentiful labour and sunshine."

Waste ponds

The concrete sewers of western cities, which run under roads and require large-scale construction are out of the question in places like Cali. Instead, low-cost sewerage can bring sanitation to poor districts at 20 per cent of the cost. Small diameter pipes run through back yards of houses and carry away sewage that usually runs in open ditches.

Treating the sewage highlights another example of the low-cost ethos advocated by the Leeds team. Human waste is treated by aerating it to help bacteria break it down. In our cities this is done with equipment that stirs the sewage slowly. In the developing world, where capital is short and electricity unreliable, the Leeds team recommends a different approach - waste stabilisation ponds.

These are large ponds where the sewage is allowed to collect and green algae carries out the aeration. The set-up costs are 10-30 per cent of western treatment systems and when the waste water has been treated it can be used for irrigation or fish farming. "Land is cheap and there's plenty of sunshine so the message is to capitalise on what they have plenty of," said Professor Mara.

Canal project

Rubbish is the other half of the equation. Even in the least developed countries each person produces half a kilogram every day. Poor or inadequate collection results in dumping in streets, clogged sewers and drainage systems, contamination of water sources and a profusion of rats, insects and disease.

Professor Stentiford advises on ways of tackling the problem. These include changing popular attitudes, organising effective collection and sorting of waste to enable recycling where possible.

Waste pickers of Ho Chi Minh City, Vietnam
Waste pickers of Ho Chi Minh City, Vietnam
Waste pickers of Ho Chi Minh City, Vietnam© Leeds University
On the Tan Hoa-Lo Gom canal project in Ho Chi Minh City, Vietnam, these ideas have been put into practice. In the tightly-packed district, rubbish collection was patchy and much ended up in the waterways. Rubbish collected was taken away in imported compactor trucks to landfill, which made things difficult and hazardous for the waste pickers who make a living combing tips for recyclable material.

The district now has an efficient collection system and recycling has been made easier and safer. Locally built tricycles carry away rubbish to a transfer station. The garbage is not densely packed and tables have been built to aid the waste pickers.

Labour intensive

"We've improved waste collection and removed the health risk. They're handling waste better now and getting it out of the city.

"Where rubbish was thrown into the canal, it is now going to the transfer station and landfill. With sorting they can get back 75 per cent of the value of plastic, for example, but the next stage is to use organic material by composting it," said Professor Stentiford.

"The secret is to achieve the same performance as the developed-world but not using the same technology, as this would be too costly. In many less-developed countries, labour is cheap, so where material sorting is done by machine in Europe it is a labour-intensive process in these countries."

According to the UN, one-in-six of the world's population lacks adequate safe water supplies and another 2.4 billion do not have adequate sanitation. The Leeds team is making a small difference to some of those lives.

"We use local staff and build on indigenous skills by providing education and training. We're fighting a losing battle against population growth so hopefully we are making a difference by helping to transfer expertise," said Professor Stentiford.

Source: The Reporter (University of Leeds monthly newsletter No. 449, 7th June 2004)