By Melanie Sevcenko, The Guardian.
No matter how you spin it, the business of raw sewage isn’t sexy. But in Colorado, the city of Grand Junction is making huge strides to reinvent their wastewater industry – and the result is like finding a diamond in the sludge.
The Persigo Wastewater Treatment Plant is processing 8m gallons of Grand Junction’s human waste into renewable natural gas (RNG), also known as biomethane. The RNG is then used to fuel about 40 fleet vehicles, including garbage trucks, street sweepers, dump trucks and transit buses.
It’s possible through a process called anaerobic digestion, which breaks down organic matter into something called raw biogas. The biogas is then collected and upgraded to RNG – at pipeline quality – and can be used as electricity, heat or transportation fuel.