In an ongoing project at Stanford University, USA, researchers lead by Craig Criddle, an expert in wastewater management, and Brian Cantwell, a professor of aeronautics and astronautics, have designed rocket thrusters that run on nitrous oxide produced by wastewater treatment.
First, the oxygen levels at the treatment plant are reduced to encourage microbes that produce nitrous oxide and methane gas. These gases are used to power the plant and a small rocket thruster to break down the nitrous oxide into clean, oxygen-enriched air. “A single thruster about the size of a basketball could potentially consume every ounce of nitrous oxide produced by a typical treatment plant,” Cantwell said.
Using less oxygen also could reduce costs: In a typical treatment plant, aeration is responsible for about half of the operating expenses.