Product, Service & Design Innovation
This Waterless Toilet Is Helping Ghana Turn Poop Into Power, Clean Water

There are still 2.4 billion people without access to toilets, risking their health and safety on a daily basis. Costs, culture, and a lack of awareness of the dangers of unsanitary practices pose substantial challenges and have resulted in an ongoing search for a sustainable and affordable “next-generation” toilet.

Researchers at Cranfield University took on the challenge and developed the nano-membrane toilet. Without using any water or electricity, the toilet removes the water from human waste and leaves solids that can be used as fuel or fertilizer, all safely free of pathogens and parasites.

As The Guardian explains, the device uses a process called “pervaporation,” where mixtures of liquids are separated by vaporization through a membrane. The vapor is recovered and drained into a reservoir so it can be used for irrigation or household washing. A rotating, sealing “flush” scraper mechanism sends waste down into a collection tank, where sediments collect at the bottom and liquid waste is filtered. The solid waste is then removed into a gasifier, which converts it into gas and energy.

The nano-membrane toilet is currently being trialled in Ghana. According to Alison Parker, a water and sanitation expert at Cranfield University, the demand for western-style seat toilets in Africa is high, while squat toilets remain culturally preferable in Asia.

Parker and her colleagues are weighing a range of options for bringing the technology to market, The Guardian reports. A rental model that removes the need for customers to pay upfront seems likely, and the costs of maintenance - which would be provided by local entrepreneurs - could be bundled into the rental package. This model has been proven with other companies, including the Clean Team project in Ghana, which rents portable toilets and charges a fee for waste collection 2-3 times per week.

“We are delighted to see this innovative solution gaining national recognition through Cleantech Innovate. The Nano Membrane Toilet has the potential to change millions of lives by providing access to safe and affordable sanitation," said Professor Elise Cartmell, Director of Environmental Technology at Cranfield University.

The nano-membrane toilet received $800,000 in financial support in 2012 from the Bill and Melinda Gates Foundation’s Reinvent the Toilet Challenge, which provides funding for the research and development of toilets that: remove germs and recover valuable resources from human waste; operate without connections to water, sewer, or electrical lines; are financially feasible for use in either the developed or developing world; and other criteria. Several universities and companies have received grants through the Challenge, including Kohler Co., which is field testing closed-loop flush toilet systems. Meanwhile, researchers from the University of the West of England and the charity Oxfam are developing a toilet that uses urine to generate electricity.


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