In October 2012, graduate student Clément Cid attended a meeting in Durban, South Africa, with the glamorous title of Second International Faecal Sludge Management Conference. Convened by the Sustainable Sanitation Alliance, the gathering brought together delegates from around the world to discuss the challenges associated with installing and maintaining sanitation systems in locations that lack the infrastructure to provide water and electricity.

He was there to present Caltech’s solar toilet, which earlier that year had won the Bill and Melinda Gates Foundation’s first Reinvent the Toilet Challenge in Seattle. But Cid didn’t really come to Caltech with a sanitation job in mind. “I mean, who wants to start working with shit? You kind of have to fall into it,” he points out.

In fact, when Cid began working with Michael Hoffmann, Caltech’s James Irvine Professor of Environmental Science, in 2011, his research focused on the use of lithium batteries to drive water splitting for hydrogen fuel production. But when Hoffmann heard about the Toilet Challenge, he recruited Cid and others to put together a proposal for a self-contained toilet and wastewater treatment system that could safely dispose of human waste for less than five cents per user per day. In the end, his team created a system that uses a solar-powered electrochemical reactor to break down water and human waste, producing fertilizer and hydrogen gas that can be stored and used in fuel cells as backup electricity, as needed.

The solar toilet’s treated water can also be reused for flushing. Through that work, Cid began to see how big a problem the lack of proper sanitation is throughout much of the developing world. According to the Gates Foundation, about 2.5 billion people across the globe practice open defecation or lack adequate sanitation facilities while another 2.1 billion use facilities that do not safely dispose of waste. This is a source of environmental pollution and contributes to the spread of diarrheal diseases such as cholera and dysentery, which kill about 700,000 children every year.

“It’s one thing to read all of the numbers, but it’s another to actually meet a person who lives in these places,” says Cid. That’s what happened at the faecal sludge conference. There, he spoke with a pit emptier, who digs up human waste in the Durban area and dumps it in a nearby treatment facility. He met with a local politician who told him that most everyone in his village defecates in a field—a practice that is not only unsanitary but also makes people, especially women and girls, feel unsafe at night.

“Hearing those kinds of stories was a real switch point for me,” says Cid. “I decided there that I wanted to focus on this problem, to make it my principal project—to really try to make a change.”  Since then, Cid and the rest of Hoffmann’s team have built working prototypes of their solar toilet, which are housed in shipping containers and include safety features such as doors that lock and minimal lighting.

The Caltech group worked with two universities and a local municipality to install three toilet systems in India and China, where people now use them regularly. There are also plans to set up several larger units with multiple stalls in South Africa. In 2013, Cid traveled to India for the first time, spending several nights in a remote village that has only one toilet. Deepen Sinha, father of Caltech undergraduate Anusha Sinha, grew up there, heard about Hoffmann’s solar toilet, and got in touch with the team to see if the system could be installed in his home town.

Although the technology was not yet ready to be used in such a remote location, Cid wanted to visit the site to experience how people were living and to see how they might react to the solar toilet. “Contrary to the popular belief that people often resist changes involving behavior, I found that the villagers were really willing to try the technology and to volunteer to take care of whatever maintenance would be needed,” says Cid.

Since that first trip, Cid has returned to India three more times to install and service the sanitation systems as well as to train local people to analyze the performance of the toilets. “Because these are first-generation prototypes, they do tend to break down. And we need to keep up with their maintenance so that people know that they can rely on them,” says Cid. “So even a relatively minor problem, like a broken pipe, can require that one of us flies over and fixes it.” In part that’s because there aren’t enough trained sanitation engineers around locally to evaluate the problems and fix them. But also the first solar toilets were built with American components that use the imperial system of measurements while most of the parts available in India use metric measurements.

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Cody Finke
Photo by Mario de Lopez Photography

“Sometimes I have to bring a second suitcase full of Home Depot connectors and pipes,” says Cid. Graduate student Cody Finke helped Cid install two of the toilets and did one of the servicing trips to India last year. He was struck by how unsustainable the process was in terms of maintenance. “The technology is awesome, but there’s no way it’s going to work if you don’t have a plan for maintenance,” Finke says. And, he points out, in the ideal situation where the team’s solar toilet really takes off and is adopted on a large scale across India—a country with a population of 1.2 billion—there could eventually be as many as three-quarters of a billion units up and running.

“You can’t send Clement to repair 750 million toilets,” he says with a chuckle. That problem got Finke thinking, and, in talking with other members of the group, he realized that the solution could be right in their pockets. They could create a mobile-based program that would empower anyone with a  cell phone—more than three-quarters of the planet’s population, according to the World Bank—to serve as a maintenance engineer for one of their toilets.

Since the solar toilet unit is relatively simple, running on one reactor unit with well-understood parameters, Finke determined that he could use inexpensive sensors to monitor the status of its parts and have the system send alerts of any malfunction via cell phone text or audio message to a local operator. That operator would then go check on the toilet unit and follow step-by-step pictorial instructions on a video display that shows how to replace the malfunctioning part.

And now that the units are being built with metric parts in the country where they will be used, replacement parts can be easily accessed at local markets, eliminating the need for suitcases filled with spares. “The cool thing about our technology is we’ve designed it so everything can be repaired with just a single screwdriver,” says Finke.

“The parts can simply be replaced.” In June 2015, Finke, Cid, and their colleagues won first place in Vodafone’s Wireless Innovation Project for their maintenance solution, a project that they have dubbed Seva, meaning “service” in Hindi. The Vodafone prize came with $300,000 in funding that will be awarded over three years. Thus far, the team has solved the self-diagnosis problem, and Finke is writing the algorithms to automate the system and interface the sensors with a mobile phone.

He says they hope to begin field-testing by early 2016. For Finke, the solar toilet and maintenance project is just the sort of thing he hoped to get involved with when he came to Caltech. Although he started out in the MD/PhD joint program that Caltech offers with USC, he decided in his first year of medical school that it wasn’t for him.

“I came in wanting to make a difference in the environmental and social problems around the world—health, pollution, these sorts of things,” Finke says. “But I quickly realized that, in my opinion, what was needed was better technology. For sanitation, you don’t solve the problem by treating dysentery and other diseases; you need technology that will prevent people from getting those diseases in the first place.”

So he dropped the medical portion and met with Hoffmann, whose website described projects aimed at developing light-harvesting materials for solar panels and determining the source of aerosol pollution. “I was interested in those projects because they both dealt with aspects of environment and health,” he remembers. “But then Mike said, ‘Right now we’re actually working with poop,’ and I said, ‘That’s great!‘

It’s an even more critical problem that’s both environmental and social.’” Organizations across the globe agree with Finke. In 2014, Indian prime minister Narendra Modi launched a campaign known as the Swachh Bharat Abhiyan to clean up the country, pledging that the sanitation problem in India will be fixed by 2019. One of the United Nation’s Millennium Development Goals for global action, approved in 2000, has been to halve, by 2015, the proportion of the population without sustainable access to basic sanitation.

While progress has been made in that direction, the UN has recommended ongoing work in this area. Similarly, the Gates Foundation says the need for better waste management in the developing world is clear. They put on the Reinvent the Toilet Challenge in part to get people talking about sanitation, a topic that can be quite taboo in many cultures.

With the Gates Foundation’s support, the Caltech solar toilet team has teamed up with companies like Kohler and Eram Scientific in India, helping those companies to adopt some of the solar toilet’s technology for use in other systems, including one for recycling treated wastewater at apartment buildings in India. The Techers have also formed a joint venture with a government-run environmental group in China called GIEI and an environmental engineering firm called CIES with the goal of manufacturing self-contained solar toilet units with multiple stalls for use in schools and other public places.

All of the groups share a common goal to make the largest positive impact on the sanitation problem in the shortest amount of time. As Bill Gates said after the Reinvent the Toilet Challenge, “Imagine what’s possible if we continue to collaborate, stimulate new investment in this sector, and apply our ingenuity in the years ahead.”

Written by Kimm Fesenmaier


Header photo by Mario de Lopez