Digesters can break down things other than sewage. The same basic biological processes can help break down agricultural waste. But the sewage-to-fuel process surprises people the most, an example of making something valuable out of hazardous materials.
On more than one occasion I’ve taken students to tour my local sewage treatment plant. (I think they should know what happens to their waste as part of being generally informed citizens and residents of the planet.) The anaerobic digesters at the plant produce methane. At least sometimes, that methane has been burned to provide heat to breakdown more waste. And sometimes it’s burned off in a flame atop the digester.
Most Americans don’t know much about where their waste goes or how it’s treated and released into the general environment. Here’s hoping we can get over our embarrassment about our bodily waste and educate ourselves at least about the basics of wastewater treatment.
Dr. E. Kirsten Peters was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.