Mr Gates said of the technology: "The current toilet simply sends the waste away in the water, whereas these toilets don't have the sewer".
Holding a beaker of human excreta that, Gates said, contained as many as 200 trillion rotavirus cells, 20 billion Shigella bacteria, and 100,000 parasitic worm eggs, the Microsoft Corp. co-founder explained to a 400-strong crowd that new approaches for sterilizing human waste may help end nearly 500,000 infant deaths and save $233 billion annually in costs linked to diarrhea, cholera and other diseases caused by poor water, sanitation and hygiene. They signed up to the sanitation project.
A number of financial institutions, including World Bank, the Asian Development Bank, and the African Development Bank, have announced that they would work to unlock $2.5 billion for sanitation projects in the cities of low and middle-income countries.
"It's also important for national and local governments to create an enabling environment with policies and regulations that encourage innovative sanitation service models, including with the private sector", he said.
"Our goal is to be at 5 cents a day of cost", Gates said in a telephone interview before the exhibition.
"Getting rid of that waste is key to human health", he said, adding that in the West "it all gets cleared up and we take that for granted". "And I certainly couldn't think Melinda will have to ask me to refrain from talking about toilets and faecal sludge at the dinner table", he said. "But I'm quite enthusiastic about what has been accomplished in just seven years".More news: Demi Lovato's First Instagram After Rehab Is a Voting Photo
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The showcased products aim to revolutionise sanitation technology by operating off-grid to separate liquid and solid waste and remove harmful by-products.
"The technologies you'll see here are the most significant advances in sanitation in almost 200 years", he said, according to a text of his prepared remarks.
However, there are still some 57 million households without their own toilets and, of those, 17 million - mainly in the countryside - face serious hygiene issues.
He explained how a toilet designed by Swiss engineering firm Helbling worked, discharging some liquid but filtering most of it back into the flushing tank for reuse.
In China, the foundation is working with three local partners to improve toilet facilities. Even the little water used is treated enough to reuse for flushing or for irrigation.