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Start Reinventing Toilets to Change the World
10 May 2019

Reinventing Toilets to Change the World

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Since the second half of the nineteenth century, humans have been enjoying the toilet more or less in the form as we know it today. In contrast to outhouses and other cruder systems, the cistern and the S-shaped drain pipe allowed the toilet to find a place inside our homes where we can take care of the necessities without suffering any of the unpleasant consequences: just flush it and you’re done. And although we may often forget to cite it as one of the greatest advances of all time, the truth is that most of us couldn’t imagine civilization without the toilet.

However, even today the toilet remains an unattainable luxury for a large part of humanity. According to the World Health Organization (WHO), only 39% of the global population has access to a safe sanitation network; 2.3 billion people don’t even have a latrine. The problem is that the toilet was conceived in developed societies for developed societies; where there are no water or sewer pipes and no treatment plants, the device itself is perfectly useless.

Only 39% of the global population has access to a safe sanitation network. Credit: Olli Pitkänen

For a large part of the world’s population, this lack is much more than a mere inconvenience—it’s a lethal risk. According to the WHO, every year 280,000 people die from diarrheal diseases caused by inadequate sanitation, although other agencies estimate even higher figures. To this is added the transmission of infections such as cholera, dysentery, hepatitis A, typhoid or polio, as well as various tropical parasites. At least 10% of the population, estimates the WHO, consumes food irrigated with wastewater.

Gates’ innovation

In 2011, the Bill and Melinda Gates Foundation, led by the Microsoft co-founder, launched the campaign called Reinvent the Toilet Challenge. Its objective is to promote technological innovation in toilets that don’t require a connection to sanitation, water or electricity networks, that eliminate pathogenic microorganisms and recycle resources such as energy, water and nutrients, that can be operated for less than 5 cents per user per day, and that can be installed and promote entrepreneurship in depressed urban areas.

In the case of Bill Gates, the economic aspect is a facet that the project does not ignore. Although entities such as the World Bank, the Asian Development Bank and the African Development Bank are promoting the expansion of sanitation systems in urban areas of the third world, the former CEO of Microsoft is taking a different path; he wants to directly do without the sanitation networks. According to Gates, the reinvented toilets will not only save $233 billion dollars in costs linked to diseases, but also create an emerging business that by 2030 will generate $6 billion a year.

Several institutions around the world have taken up the challenge laid down by Gates, which to date has supported the projects of 16 research teams with a total of $200 million and has promised $200 million more for the coming years. One of the solutions in development, from the California Institute of Technology, consists of a toilet powered by solar energy and equipped with an electrochemical reactor that degrades waste to produce fertilizer and hydrogen. In turn, this gas can be stored in fuel cells to supply energy in the absence of sunlight. Another prototype, from the University of Loughborough (United Kingdom), carbonizes the waste to generate salts and clean water, and is powered by the combustion of the biological carbon produced.

A third design, from the University of Toronto (Canada), dries and incinerates the stool at low temperatures for 24 hours, while the urine passes through a sand filter and is disinfected by ultraviolet light. According to what the project manager, chemical engineer Yu-Ling Cheng, told OpenMind, the product development phase is already underway. “Major technical innovations have been developed. Now we are focused on cost reduction, improving operability, and addressing all the required details for a viable commercial product,” she explains.

The University of Toronto is working in a design that dries and incinerates the stool. Credit: University of Toronto

First tests in the real world

Some of the proposals are already making their way to their first tests in the real world in places like Durban, a South African city that is growing at a faster rate than its sanitation infrastructure can keep up. There the Nano Membrane Toilet created at Cranfield University (UK) is being tested. This is a toilet whose receptacle tilts downward to be emptied and mechanically cleaned without consuming water, depositing the waste in an internal container.

From there, the solids are transported by an Archimedes’ screw to be dried and burned, providing energy for the processing of the liquid through a membrane that produces water suitable for washing or watering plants. “We are still working on the integration of the back end components, the membrane and combustor, with the flush and screw,” Alison Parker, the person in charge of communication for the project, told OpenMind.

Projects such as Cranfield’s depend to a large extent on the mechanical functioning of certain components that must operate correctly in harsh conditions and with minimal maintenance. In other cases, the obstacle is to ensure that the high technology developed in the laboratory can be brought to the field within the strict cost limit imposed by the Gates challenge.

This is the case with the toilet developed by Duke University, which uses diamond electrodes doped with boron for the electrochemical treatment of wastewater. Since this material is not exactly cheap, researchers have tried other alternatives. “Rather than running experiments to find the best material for a job —no matter the cost— we found a solution that was not good, but good enough and much cheaper,” said Jeffrey Glass, one of the people responsible for the project. Thanks to this change, the Duke toilet is already being tested in Durban and in a textile factory in India.

It is still too early to know if these or other ongoing projects will come to fruition in commonly used products. But in addition to the main objective of bringing sanitation to where there is none, Gates trusts that these new generation toilets will also become a desirable option for citizens of developed countries, as alternatives to traditional ones. “The toilet has not changed in more than a century,” says Gates. It’s time.

Javier Yanes


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