Billions of years ago, when Earth’s atmosphere reeked of unbreathable gases, microbes evolved in the absence of oxygen. As Earth matured and the nitrogen-oxygen atmosphere formed, these anaerobic, or oxygen-averse, bacteria retreated into the mud of the ocean floor and other environments where they would be safe from oxygen-rich air.
For over a century, wastewater treatment has relied on aerobic bacteria that require oxygen to survive. Wastewater treatment plants provide that oxygen with huge and costly electrically powered blowers.
“The time has come for a technology change,” said Eric Hansen, the Stanford-trained civil engineer spearheading Silicon Valley Clean Water’s involvement in the project. “Taking those blowers out of the process helps to reduce the cost of water recovery and makes municipal treatment operations more sustainable.”
Reducing cost is just one advantage of wastewater treatment based on anaerobic bacteria, according to Sebastien Tilmans, the civil engineer who runs the Codiga Resource Recovery Center on the Stanford campus. At Codiga, which has a smaller version of the technology, the oxygen-averse bacteria clean wastewater and belch out methane. Commonly known as natural gas, this output can be burned as fuel or used as a chemical feedstock to make biodegradable plastics. That, Tillman said, exemplifies a change in thinking.
