Few of us have anything good to say about wastewater. Once we’ve flushed the toilet or rinsed our hair, the used water simply disappears, never to be thought of again.
But Craig Criddle has a different perspective. “Instead of thinking about wastewater in the negative sense all of the time, let’s think about what resources are in it that might be useful,” says Criddle, a Stanford professor of civil and environmental engineering and senior fellow at the Woods Institute for the Environment at Stanford University.
Today, Criddle is leading an effort to find economical ways of recovering valuable products from wastewater. “There is value to be found in wastewater,” he says. “Of course, it’s got a lot of bad stuff that we’ve got to get rid of, like pathogens and salt. But it also has biodegradable organics and nutrients – like nitrogen and phosphorus – that are potentially useful.”
The most valuable component of wastewater is the water itself, he says: “Wastewater is 99.9 percent water. Right now, we’re looking at ways to drive down the cost of recovering good, clean water from wastewater for a variety of applications, like washing clothes and flushing toilets. And if you remove the salt, the water becomes even more useful for things like aquifer storage and ecosystem restoration.”
Most wastewater systems in the United States release treated water back into rivers, lakes or the ocean without reuse, Criddle says. “If that water is reused locally, it decreases the amount of freshwater that needs to be imported, often from distant locations at great expense,” he adds. More Details
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