At dawn every Sunday, Joseph Irungu leads an army of 50 men pushing hand carts fitted with old 42-gallon oil drums through the narrow alleyways of one of Kenya's most populous slums.
With their bare hands, they use buckets to draw the feces from the pit latrines in Korogocho, fill the oil drums and push them to a river to deposit the waste. Every trip leaves the men with splotches of sewage on their faces and hands.
Irungu has been leading this sanitation brigade since 1998, when the Nairobi City Council refused his request to drain the pit latrine at his plot of rental houses.
"It was too much," he said. "I had to do something, so I picked up a bucket and drained it myself. I realize that many other landlords were facing similar problems and a business opportunity presented itself."
Irungu's enterprising spirit was echoed across the continent Tuesday, when the world's largest charitable foundation announced its newest venture: an effort to reinvent the toilet to bring safe, clean sanitation to millions of poor people in the developing world.
At the AfricaSan Conference in Kigali, Rwanda, the Bill & Melinda Gates Foundation announced $42 million in grants to encourage innovation in the capture, storage and repurposing of waste as an energy resource.
More than 2.6 billion people around the world don't have access to safe sanitation. Instead of using toilets connected to sewer lines, most leave their waste on the ground or in a ditch or pit. The result is unsightly, unsanitary and contributes to illness.
Some 1.5 million children die each year from diarrhea-related diseases. Because the Gates Foundation believes most of these deaths could be prevented with proper sanitation, safe drinking water and improved hygiene, foundation officials are in Africa this week to launch this new initiative.
The foundation is focusing on toilets and sanitation, in part, because it's the least attractive part of world development, said Frank Rijsberman, director of the foundation's water, sanitation and hygiene initiative.
"It's almost taboo. Who wants to talk about shit? It's not exactly a subject in polite conversation," he said.
Before the end of the year, the foundation hopes to have 50 to 60 groups working on ideas for the next generation of toilets, which should run without water or electricity and not be attached to a sewer system. Rijsberman said they're aiming for a toilet that is useful in more than one way, such as one that turns waste into something that can be used for energy.
If all goes as planned, in three to five years there will be a handful of solutions that will lead to products or innovations to serve tens of millions of people, he said.
Irungu, 47, says the main problem in communities like the Korogocho slum is the lack of sewage facilities and access to water. He has already seen a positive impact from his efforts, including a decrease in cholera outbreaks.
"This place used to smell because people would go the toilet in (plastic) bags and throw them in the streets because they could not go to the toilets which were overflowing with waste," he said.
Paying to use clean toilets and water is an extra expense many slum dwellers cannot afford, so they end up using the dirty facilities that can expose them to diseases. The use of a toilet costs about two cents, or two Kenyan shillings.
If better toilets are introduced Irungu will lose his business, but he says he feels guilty disposing waste in a river. He says he has no alternative. The slum was built on rocky land, so many landlords dig shallow pit latrines that fill quickly because they are sometimes used by as many as 30 people.
For every latrine drained, Irungu takes home about $2, a solid income in an area where many residents earn less that $1 a day. Through this work he has been able to educate his five children, he said.
Korogocho resident Veronica Wanjiru, 29, who has two children aged 7 and 11, says cleanliness is a problem.
"Most of the tenants choose to use a donor-funded toilet facility which you pay 2 shillings," she said. "Many of us cannot afford this fee so our children use potties until they are even 14 years or for those who cannot afford that they use paper bags which are then thrown into a ditch."
Wanjiru said that if her family used the public toilet twice a day, it would cost her 12 shillings (13 cents), which she cannot afford. Instead, her children leave their waste in a portable, self-contained toilet chair. She dumps its contents into a ditch.
"I know that disposing of feces in the ditch is bad but I have no choice. I have no toilet. I don't have a steady job," said Wanjiru, who washes clothes for a living. "Disposing the feces in the ditch is bad because that is where my children play."
The Gates Foundation was created in 2000 by the Microsoft Corp. chairman and his wife. (Msnbc.com is a joint venture of Microsoft and NBC Universal.)