In a new WIRED article entitled “The city of tomorrow will run on your toilet water,” Professor Sybil Sharvelle describes uses for recycled wastewater and the fatty acids generated by the microbes in wastewater. From jet fuel to agricultural irrigation, wastewater has many circular uses.

Excerpt of article:

A wastewater facility can also create fuel in oxygen-free chambers, where microbes eat the solid waste and release methane “biogas” as a byproduct. “This biogas can be burned to generate heat,” says You. In Ithaca, New York, that can fully power a wastewater facility itself, but You has also been experimenting with using biogas to heat nearby buildings, including a medical center. Heating a building with natural gas adds carbon emissions to the atmosphere, but as biogas comes from the crops we eat and poop into the sewer system, which grew by drawing down carbon from the atmosphere, so burning it forms a carbon loop.

Before those microbes create biogas, they also generate volatile fatty acids. These could be made into jet fuel, or maybe even a fuel for fleets of city vehicles, says environmental engineer Sybil Sharvelle, who studies wastewater at Colorado State University. “There’s a lot of value in all sorts of those volatile fatty acids,” says Sharvelle.

In addition to using the waste solids as compost, like Epic Cleantec is experimenting with, Sharvelle notes that urban farms could benefit from using recycled wastewater that’s been disinfected for use on crops, but with the nitrogen and phosphorus left in. Those are essential nutrients for plants, but are actually difficult to remove from water. “If you can leave nitrogen and phosphorus in the system, that’s a much more energy-efficient way to just make use of those nutrients directly,” says Sharvelle.

Read the full article at: https://www.wired.com/story/the-city-of-tomorrow-will-run-on-your-toilet-water/#:~:text=But%20in%202026%2C%20San%20Diego,water%20molecules%20can%20get%20through.