4 toilets of the future that are backed by Bill Gates

Global sanitation is one of the most pressing public health crises in the world: Some 2.5 billion people don't have access to clean living conditions.

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In 2012, the Gates Foundation issued a challenge to design a revolutionary toilet that was safe, sustainable, and affordable for people in these areas.

The four winning designs were awarded grants totaling $3.4 million, with the expectation that they could help transform underserved areas.

RTI toilet
RTI International

From a waterless toilet that relies on nanofibers to a solar-powered machine that produces fertilizer, the designs are as complex as they are clever.

Here are where the four winners stand four years later. 

 

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Developed by researchers at Cranfield University, the Nano Membrane Toilet earned an $810,000 grant.

nano toilet
Cranfield University
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The innovative system uses no water whatsoever.

Instead, the movable tank rotates 270 degrees to let the waste fall to the bottom of the tank, where it separates from liquid.

A rubber scraper removes any excess waste before the bowl rotates back to its normal position.

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Bundles of extremely thin fibers, known as nanofibers, help move the water vapor into a vertical tube in the back of the tank.

From there, a silo of beads help condense the vapor into water droplets, which move through a pipe into a holding tank in the front of the toilet.

Cranfield researcher Alison Parker tells Tech Insider that one toilet can accommodate up to 10 people for no more than $0.05 a day per user. A trial run will take place in Ghana later this year.

The system also can create jobs, as someone must visit the site weekly to replace the tank's waste (which will have turned into fertilizer) as well as the toilet's battery every few months. 

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At the University of Colorado Boulder, a $780,000 grant helped scientists create "Sol-Char," a method of burning a biomass (in this case human waste) to produce biological charcoal, or biochar.

Sol Char Toilet
Sol-Char

Sol-Char relies on solar power. As the sun's energy gets absorbed by the eight solar dishes, it travels through bundles of fiber-optic cables that burn a person's solid waste so that it becomes "char."

This char can be used to replace traditional wood charcoal or chemical fertilizers. A user's urine, meanwhile, can be used as a nitrogen-rich fertilizer.

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Sol-Char can comfortably handle a family of four, and can also expand as needed provided it has enough solar dishes to receive the incoming energy.

Sol Char Toilet
Sol-Char

"In terms of our latest model, we have been working in the lab on improving the efficiency of the core technology and reducing the cost," Anna Segur, Sol-Char's program manager, tells Tech Insider. "We are looking for partners and investors to build a Phase II prototype for field testing that incorporates all these improvements."

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In India, where 774 million people still lack clean access to a toilet, the $450,000-backed eToilet could revolutionize sanitation.

etoilet
Eram Scientific Solutions

Developed by Eram Scientific Solutions Private Limited, the eToilet is India's first automatic, unmanned, electronic public toilet. Each unit costs roughly $6,800 for buyers, and just a few cents to use. 

As Ria John, a senior manager at Eram, tells Tech Insider, the 35-square-foot stall can be modified to fit its setting.

There are eToilets for the general public, for schools, individual communities, and toilets just for women that come with sanitary napkins and their own incinerators.

 

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To date, more than 1,600 eToilets and 500 sewage treatment plants have been set up in 19 states across India.

Adambakkam Bus Depot etoilet
Eram Scientific Solutions

Each toilet comes with a 225-liter tank for flushing, self-cleaning toilet seats that cycle every 5 to 10 users, and backup power systems in the event of a local outage. According to Eram, the goal is to kickstart a strong sanitation infrastructure in India.

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The Gates Foundation's largest grant, of $1.3 million, went to RTI International for its Integrated Waste Treatment System.

RTI toilet
RTI International

The design is something of a combination of the other three: It disinfects liquid waste, dries out and burns solid waste, and turns that into electricity that further powers the toilet. 

According to Myles Elledge, senior director for International Development Policy and Planning at RTI, it's meant for a shared setting to accommodate up to 50 people a day. One unit will cost roughly $2,500.

In October of 2015, RTI researchers went to CEPT University in Ahmedabad, India to conduct field tests, where it was received well and the technology reportedly worked as intended.

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As with all of the designs, the primary criticism centers on whether a complex machine is the best solution in underserved areas.

RTI toilet
RTI International

Critics point to the need for simplicity, not technology that can break down at random.

Still, the need for better sanitation is real. The RTI International team is working to improve the disinfection unit that handles incoming urine as well as the combustion process that turns solid waste into dried-out pellets for energy.

A fully automated system could restore dignity to millions.

Bill Gates Public Health
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