共享题干题Bill Gates believes the world needs better toilets. Specifically, toilets that improve hygiene, don’t have to connect to sewage systems at all and can break down human waste into fertilizer.
 So on Tuesday in Beijing, Mr. Gates held the Reinvented Toilet Expo, a chance for companies to showcase their takes on the simple bathroom fixture. Companies showed toilets that could separate urine from other waste for more efficient treatment, that recycled water for hand washing and that sported solar roofs.
 It’s no laughing matter. About 4.5 billion people  more than half the world’s population  live without access to safe sanitation. Globally, Mr. Gates told attendees, unsafe sanitation costs an estimated $223 billion a year in the form of higher health costs and lost productivity and wages.
 The reinvented toilets on display are a culmination of seven years of research and $200 million given by the Bill and Melinda Gates Foundation, which the former software tycoon runs with his wife, since 2011. On Tuesday, Mr. Gates pledged to give $200 million more in an effort get companies to see human waste as a big business.
 Mr. Gates said in an interview that “it will be at least a decade” before the reinvented toilets reach tens of millions of people in the poorest areas, and they will have to prove both practical and economical. “Nobody wants overnight solutions” in sanitation,he added.
  Though the products on display on Tuesday were nowhere as flashy, Mr. Gates has drawn criticism for giving thousands of dollars to universities in developed countries to create high-tech toilets that will take years to pay off  if they ever do.
 “Sometimes doubling down is necessary but you’ve got to be reflective.” said Jason Kass, the founder of Toilets for People, a Vermont-based social business that provides off- grid toilets. “Has any of the approaches done in the last five years created any sustainable lasting, positive impact vis a vis sanitation? And the answer, as far as I can see, is no. It might be a thing like the space program where people have fantasies about colonizing the moon and Mars, but it’s really not that practical,” he said.
 Mr. Gates acknowledged that some reinvented toilets, in small volumes, could cost as much as $10,000, but added, “That will pretty quickly come down. The hard part will be getting it from $2,000 to $500. I’d say we are more confident today that it was a good bet than where we started, but we are still not there.”
 The Gates Foundation said the World Bank, the Asian Development Bank and the African Development Bank would commit $2.5 billion in financing for sanitation projects that provide people in all parts of a city  including the poorest neighborhoods  with safely managed sanitation services.
 “We see ourselves on the cusp of a sanitation revolution,” Mr. Gates told expo attendees on Tuesday.
 At a showroom in an art center in Beijing, companies including China’s Clear,Ecosan and CRRC, Sedron Technologies of the United States, India’s Eram Scientific and Switzerland’s Blue Diversion Autarky displayed toilets that could separate urine and recycle water for hand washing.
 During his opening remarks, Mr. Gates said he started getting interested in sanitation after he stopped working full time at Microsoft and began traveling more frequently to poor countries with his wife, Melinda.
 Holding up a beaker of fecal matter, Mr. Gates reminded the audience that human waste is disgusting, containing 200 trillion rotavirus cells and 100,000 parasitic worm eggs, among other bacteria.
 Mr. Gates’s efforts to bring the discussion of toilets into the mainstream have legitimized a topic that many have avoided talking about for decades, said Jack Sim, the founder of the World Toilet Organization, a Singapore-based nonprofit organization committed to improving toilet and sanitation conditions worldwide. “The subject of toilets has been a neglected subject for some time,” said Mr. Sim. “The Gates Foundation is part of this momentum of breaking the taboo.”