Twenty-two universities submitted proposals and eight, including the National University of Singapore (NUS), have received the nod from the Bill and Melinda Gates Foundation to fine-tune their ideas.
The NUS team - the only team from Asia - won a US$280,500 (S$337,700) grant from the foundation last month to come up with a toilet that would cost less than five US cents a user a day.
The competition is intended to benefit the 2.6 billion people, or 40 per cent of the world's population, who have no access to safe and reliable toilets.
The teams will work on their projects for a year and the prototypes will be judged by the foundation in August next year.
Up to three prizes of between US$40,000 and US$100,000 will be awarded.
The foundation is headed by Microsoft founder Bill Gates and his wife, as well as his father.
The NUS team submitted a proposal for a toilet that turns faeces and urine into fertiliser and drinking water.
The communal toilet, expected to serve up to six households, separates faeces and urine and transfers the faeces to a collection point for drying and burning to be used as fertiliser.
Heat from the burning powers a desalination system that extracts water from urine.
The water is disinfected to make it drinkable.
Left-over liquid from the urine is concentrated so it can be used as fertiliser.
Project leader Ng How Yong, an associate professor at the NUS engineering faculty and director of the Centre for Water Research, said the toilet would be especially useful in rural areas that depend on agriculture.
He hopes that it can be implemented in developing countries such as India and Bangladesh as well as those in Africa.
Other finalists include Stanford University in the United States, the University of Toronto in Canada and the Swiss Federal Institute of Aquatic Science and Technology.
Their ideas include a solar-powered toilet that generates hydrogen and electricity, and a toilet that produces charcoal, salt and clean water from waste.
The competition is part of the foundation's US$42 million programme to improve sanitation in developing countries.
The World Health Organisation estimates that 1.8 million people die each year due to diarrhoea-related diseases, mostly caused by poor sanitation.
Children under five years old make up 90 per cent of the fatalities.
It added that improving sanitation can reduce assaults against women which take place in dimly lit and unsafe outdoor toilets.
The Straits Times, 19 August 2011
