It's not every day that one of the world's richest men walks on stage carrying a jar of human feces, but that's precisely what Bill Gates did in Beijing on Tuesday.
The Microsoft founder was in China to talk toilets at the Reinvented Toilet Expo, an event showcasing the latest in high-tech sanitation to entrepreneurs, development banks and government agencies.
Improving the technology behind toilets is one of Gates' self-confessed obsessions. "It's been done this way for centuries. What's been the latest advance in toilets, double-ply toilet paper?" he joked onstage.
Through his foundation, the tech mogul has spent the last seven years applying the same innovative approach that made him a billionaire to improving sanitation, and with good reason. (Note: the Gates Foundation is a funder of this blog and of NPR.)
According to the World Health Organization, more than 4.5 billion people do not have access to toilets where waste is treated and disposed of safely. When human waste is poorly managed, pathogens can seep into the environment, causing diseases like diarrhea, cholera and typhoid.
"This small amount of feces," Gates said, brandishing the jar of excrement, "could contain as many as 200 trillion rotavirus cells, 20 billion shigella bacteria and 100,000 parasitic worm eggs."
Gates' poop presentation has its roots in a visit to a slum in Durban, South Africa with his wife Melinda a decade ago.
"We visited communities where children were playing in lanes filled with human waste ... where the stench of community toilets was so bad that people didn't want to use them, and where families drank water contaminated with human waste," Gates said.
In 2011, the Gates Foundation launched the Reinvent The Toilet Challenge, calling on scientists, universities and companies to come up with a toilet that didn't require a sewer system to safely dispose of human waste. The foundation has since contributed $200 million to research and development.
The result? Two floors of sanitation solutions on display for the first time together in Beijing.
The 20 or so exhibitors fell mainly under two categories: reinvented toilets, household toilets with built-in waste processors and omniprocessors, commercial-grade waste treatment centers.
The reinvented toilets look and feel like your average latrine. But instead of being connected to a sewage system, which flushes waste far, far away, everything is processed internally by mechanisms often beneath or behind the potty.
The Nano Membrane Toilet, created by researchers at Cranfield University in the U.K., is just one example. Designed for the home, the unit operates without water or a power source.
Closing the toilet lid triggers a rotating mechanism which begins to process the deposited waste. The machine uses a "nanostructure membrane" to filter out pathogens from the liquid waste. Then it is stored as reusable water in a tank beneath the pedestal. Solids are turned into ash via a combustor and converted into enough electricity to charge your cell phone. The product is still in prototype phase, with field-testing planned for next year.
Using your poop to power your phone is one thing, but omniprocessors take human waste recycling to another level. These aren't toilets, but self-powered treatment plants which transform human waste into products with commercial value.
Sedron Technology's Janicki Omniprocessor turns large volumes of fecal sludge into clean drinking water, electricity and ash. Once plugged into a natural gas source, the system generates enough energy to power itself. Liquid waste is boiled and the air particles are filtered before being condensed into potable water.
"A sludge processor dries incoming waste, then the system burns solids to create ash and electricity. Then there's a drying process where we evaporate all the liquid to create clean drinking water," says Lucas Reid, a program manager at Sedron Technology.
Costing $2 million and roughly the size of a basketball court, the omniprocessor looks like a complex network of interconnected water tanks. Built for large communities, it produces almost 6,000 gallons of clean drinking water per day and between 100-200 kilowatt hours of electricity. The Washington state-based company has sold its first model to a client in Dakar, Senegal, and is keen to scale up production.
Highlighting the potential profitability of new toilet technologies was a key theme of the expo. "We need to shift our mindset from looking at sanitation as just waste to be processed and see it as an economic opportunity," said World Bank president Jim Yong Kim, who also gave a speech at the Beijing toilet expo.
According to Gates, the reinvented toilet market could generate $6 billion a year worldwide by 2030. Japan's LIXIL group, the sanitation giant behind toilet brands such as American Standard and GROHE, is so convinced of the potential profitability that it's partnering with the Gates Foundation to pilot reinvented toilets in at least two international markets.
Right now, the market for reinvented toilets and high-tech sanitation solutions is in its infancy. This makes the choice of China as the expo venue clear. With a population of 1.3 billion people and a booming start-up industry, data and business research firms Crunchbase and Pitchbook point to it as a good place to ramp up production and attract capital.
The country is also no stranger to toilet reform. In 2015 Chinese president Xi Jinping declared a "Toilet Revolution." He called on local governments to improve sanitation in an effort to attract more tourism, saying a bad "toilet landscape" had marred China's image.
But toilet innovations may be a harder sell in other countries. Sanitation just isn't sexy. In fact, it stinks. According to the World Health Organization governments, including many of those in Sub-Saharan Africa and Latin America, often neglect to consider safe sanitation when drawing up budgets and policies.
"To have any hope of solving sanitation problems," said Kim of the World Bank, "we have to break taboos and get over our discomfort in talking about poop."
He hailed the expo as a milestone in the global health. "Trust Bill and Melinda Gates to make poop cool, that's the real innovation," said Kim.
His highest praise, however, was for Gates Foundation staff. "I want to thank the people at the foundation who prepared the jar of poop for Bill," he said laughing. "That is truly a new level of dedication."
Katrina Yu is an Australian journalist, video producer and writer who has been based in China for five years. Her reports have appeared on the PBS Newshour, France24, Al Jazeera Online and SBS Australia.