NAIROBI (Reuters) - Entering Nairobi's fetid slums the senses are first assaulted by a gagging stench and the sight of garbage everywhere, some even hanging from trees or smoldering in acrid fires.
The city government does not recognize the "informal settlements" where more than 60 percent of the population live, so no services are provided and no garbage collected.
The result is frighteningly unsanitary conditions.
Rubbish, "flying toilets" -- excrement in plastic bags -- and even aborted fetuses pile up in dumps along the muddy tracks or find their way into the rivers, where children play along the banks.
Garbage pollutes the air and seeps into ground water, or is picked over by pigs and other farm animals, its toxins entering the food chain and causing intestinal diseases.
Now a "community cooker" project in Africa's biggest slum, Kibera, offers a way not only of getting rid of garbage, but of creating work for unemployed youths, and providing hot water and cooking facilities.
The people developing the project, a Nairobi architectural practice, the United Nations Environment Program (UNEP) and a Kenyan non-governmental organization, hope it can be a prototype for cookers all over Africa.
The cooker, dreamed up by Kenyan architect Jim Archer, has taken eight years to develop and is still overcoming design problems.
"My thinking was how do we get rid of the rubbish and ... how can we induce people to pick it up. Then I thought, well if we can convert it to heat on which people can cook..."
Industrial incinerators from Europe would cost $50 million. "This was way out of the realms of reality ... and it wouldn't give anything back," Archer said.
He set out to design and find financing for a simple, labor intensive device with a minimum of moving parts that would be easy to repair and require no imported technology.
Archer consulted engineering companies in Britain.
"They just couldn't understand simplicity. They could computer control it. They could mechanically handle the rubbish. But we want this to be labor intensive because there are so many people with no jobs."
Then Archer found brass foundry worker Francis Gwehonah, nicknamed "Firebox" because of his remarkable self-taught skill at furnace building.
"It is a talent in me. I haven't gone through any kind of training," says Gwehonah.
First attempts to burn the rubbish produced choking smoke and soot that brought complaints from Kibera residents that the cooker caused more pollution than it eliminated.
By trial and error Gwehonah found that if he superheated a steel plate in the cooker he could ignite discarded sump oil, another pollutant.
By vaporizing droplets of water to split off the oxygen and mixing it with the burning oil, he has pushed up the temperature to more than 600 degrees centigrade and is working to get it even higher to destroy all the toxins in the smoke.
The scheme, run by a community group in Kibera's Laini Saba area, where 50,000 people live, has more benefits than burning garbage.
Local youth workers who go door to door collecting rubbish -- for which they are paid a small fee by slum dwellers -- can exchange it for cooking time or hot washing water.
John Githinji, from the 40-strong youth group that collects the rubbish, stoked the furnace with sweat pouring from his face. "People throw rubbish on the ground and it causes sickness," he grunted through the smoke.
Water will also be boiled for drinking and eventually the cooker will be used for baking bread and cakes to sell.
"The trash has started to help us a bit after the cooker came. There are less diseases like diarrhea and the environment has improved. ... I think burning the rubbish will bring good health to this community," said Patricia Ndunge as she fried onions on the cooker.
About 60 percent of the slum rubbish can be burned if the temperature is high enough. Much of the rest can be sold to recycling companies.
The project, funded by Archer and his business partner, UNEP and a local paints company, has cost around $150,000 to develop, but once the prototype is perfected, future cookers should cost less than $10,000.
Kenya's big supermarket chain Nakumatt has pledged to fund at least 20 more slum cookers and Archer believes they can eventually be adapted to distil dirty water, fire pottery kilns and operate scrap metal foundries.
"Most people dump in rivers and roadsides, on top of roofs, or on railway sidings. Finally there is somewhere we can take our waste, " said Celine Achieng of the Umande Trust NGO working in Kibera, where more than 800,000 people live.
"This will solve a lot of problems. We are trying to change perceptions to persuade people not to take their waste to the river."