Scientists in Singapore have invented a new toilet system that will turn human waste into electricity and fertilisers and also reduce dramatically the amount of water needed for flushing.
Dubbed the No-Mix Vacuum Toilet, it has two chambers that separate the liquid and solid wastes.
Using vacuum suction technology, such as those used in aircraft lavatories, flushing liquids would now take only 0.2 litres of water while flushing solids require just one litre.
A conventional water closet uses about 4-6 litres of water per flush. If installed in a public lavatory and flushed 100 times a day, this next generation toilet system, will save about 160,000 litres in a year – enough to fill a small swimming pool.
The scientists are now looking to carry out trials by installing the toilet prototypes in two Nanyang Technical University restrooms.
If all goes well, the world can expect to see and even sit on the new toilet in the next three years, they predict.
Associate Professor, Wang Jing-Yuan, director of the Residues and Resource Reclamation Centre (R3C) at NTU who is leading the research project, said that their ultimate aim is not only for the new toilet system to save water, but to have a complete recovery of resources so that none will be wasted in resource-scarce Singapore.
“Having the human waste separated at source and processed on-site would lower costs needed in recovering resources, as treating mixed waste is energy intensive and not cost-effective,” Prof Wang said.
“With our innovative toilet system, we can use simpler and cheaper methods of harvesting the useful chemicals and even produce fuel and energy from waste.”
So how does it work? The No-Mix Vacuum Toilet diverts the liquid waste to a processing facility where components used for fertilisers such as nitrogen, phosphorus and potassium can be recovered.
At the same time, the solid waste can be sent to a bioreactor where it will be digested to release bio-gas which contains methane.
Methane is odourless and can potentially be used to replace natural gas used in stoves for cooking. Methane can also be converted to electricity if used to fuel power plants or fuel cells.
“Grey water” (used water from the laundry, shower and kitchen sink) can be released back into the drainage systems without further need for complex waste water treatment, while leftover food wastes can be sent either to the bioreactors or turned into compost and mixed with soil, resulting in a complete recovery of resources.
This next-generation toilet and resource recovery system took the team one-and-a-half years to develop.