The inventors in Singapore call it the No-Mix Vacuum Toilet and it has two chambers that separate the liquid and solid wastes. Using vacuum suction technology, like you find in airplane lavatories, flushing liquids requires only 0.2 liters of water while flushing solids require just one liter. The existing conventional commonly used in Singapore need 4 to 6 liters of water per flush so a single public toilet, that may be flushed 100 times a day, could save about 160,000 liters of water in a year – enough to fill a small pool.
The inventors are installing the toilet prototypes in two Nanyang Technological University restrooms. If all goes well, the world can expect to see and even sit on the new toilet in the next three years. NTU Associate Professor Wang Jing-Yuan, Director of the Residues and Resource Reclamation Centre (R3C), said that their goal 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. 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.”
NTU R3C's No-mix Vacuum Toilet. Credit: NTU
How it works
The No-Mix Vacuum Toilet will divert the liquid waste to a processing facility where components used for fertilizers such as nitrogen, phosphorous and potassium can be recovered.
The solid waste is sent to a bioreactor where it will be digested to release bio-gas which contains methane. Methane is used to replace natural gas used in stoves for cooking and can also be converted to electricity if used to fuel power plants or fuel cells.
‘Grey water’ - the term for 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.
Aiming to convert all waste to resource, the new toilet system which is part of a project that has received $10 million from Singapore’s National Research Foundation’s Competitive Research Programme in 2010, will be useful for new housing estates, hotels, resorts, and especially communities not linked to the main sewerage system and so require their own sewerage facilities.
Five NTU researchers will showcase the new loo at the upcoming WasteMET Asia 2012, held from the July 1st-4th at Marina Bay Sands’ Sands Expo and Convention Center.
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