Scientists
from Nanyang Technological University (NTU) have invented a new toilet
system that will turn human waste into electricity and fertilizers and
also reduce the amount of water needed for flushing by up to 90%
compared to current toilet systems in Singapore.
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 L of
water while flushing solids require just 1 L.
The
existing conventional water closet uses about 4 to 6 L of water per
flush. If installed in a public restroom flushed 100 times a day, this
next generation toilet system, will save about 160,000 L in a
year—enough to fill a small pool 10 x 8 x 2 m.
The
NTU scientists are now looking to carry out trials by installing the
toilet prototypes in two NTU restrooms. If all goes well, the world can
expect to see and even sit on the new toilet in the next three years.
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.”
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.
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.
At
the same time, the solid waste will be sent to a bioreactor where it
will be digested to release bio-gas which contains methane. Methane is
odourless and can 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.
Assisting
Assoc Prof Wang in the project are four other NTU researchers—Asst Prof
Chang Wei-Chung, Dr Chen Chia-Lung, Dr Apostolos Giannis and Dr
Rajinikanth Rajagopal. This next-generation toilet and resource recovery
system took the team one and a half years to develop and will be
showcased to the industry at the upcoming WasteMET Asia 2012, held from
the 1st to 4th July this year at Marina Bay Sands’ Sands Expo and
Convention Center.
NTU joins global waste-to-energy network
In
conjunction with WasteMET Asia 2012, NTU will also be signing a
Memorandum of Understanding (MOU) with the Earth Engineering Centre of
Columbia University in the US to be part of a global community in
waste-to-energy research.
The
collaboration paves the way for NTU to join a global network of
Waste-to-Energy Research and Technology (WTERT) groups, and the
WTERT-Singapore will be the first such regional node in Southeast Asia.
Each WTERT group around the world aims to bring together academic,
industry and government research groups concerned with sustainable waste
management, to share research data and best practices through
information disseminated via online web portals, publications and
presentations.
Professor
Ng Wun Jern, Executive Director of the Nanyang Environment and Water
Research Institute (NEWRI), which houses R3C, said: “This partnership is
a global step forward for Singapore in advancing the waste management
industry towards a resource reclamation industry.”
“As
part of WTERT, we are able to share our knowledge broadly with the
other members in waste reclamation community, and to spread awareness
about Singapore’s ground breaking research in this area, such as the
No-Mix Vacuum Toilet system which R3C has developed,” he added.
