Inside Bill Gates’ effort to turn human waste into potable water
Author Nicholas Derenzo Illustration Jameson Simpson
Earlier this year, Bill Gates took one small sip for man, one giant gulp for mankind. In a much-publicized photo (inset), the richest man in America was seen grinning and drinking a glass of water. But it wasn’t—as you might expect for a man of his status—Evian or Fiji water. In fact, about five minutes before the shot was taken, that very water had been raw human sewage. As part of its ongoing quest to help the more than 2.5 billion people who don’t have access to effective sanitation, the Bill and Melinda Gates Foundation has invested in Janicki Bioenergy’s Omni Processor. This low-cost, hyperefficient sewage treatment plant produces clean drinking water that meets both FDA and World Health Organization standards and generates the very energy it requires to run. Late last year, Janicki Bioenergy, which is based north of Seattle, got a prototype up and running in Washington state, and this year, the company enters the developing world with a plant in Dakar, Senegal. Here’s how it works.
1. The sewage sludge is fed into the plant by conveyor belt and dried in a tube that separates solid waste from water. The Omni Processor’s intensely hot incinerator reaches 1,000 degrees Celsius, scorching enough to kill all pathogens and, perhaps more important for those living downwind, to operate without the expected offensive smell.
2. Converted into vapor, the water is spun in a centrifuge to remove remaining particles and then fed through two layers of filters. Next, it is cooled and condensed, at which point it is filtered one more time. The latest model can yield 86,000 liters of pure drinking water each day.
3. The remaining solids are then fed into an incinerator, yielding a high-powered steam that drives a generator, which in turn produces the very electricity that runs the plant (the Dakar unit produces 150 kW per day), plus excess energy that can be diverted back to the surrounding community. Another byproduct is a phosphorus-rich, disease-free ash that can be used as fertilizer. And the circle of life continues.