Wastewater methane used as fuel

By Andrew Freiden - bio | email
Posted by Terry Alexander - email

HENRICO, VA (WWBT) - When you think of an industry that's "going green" wastewater treatment is probably not the first to come to mind. After all, these facilities handle raw sewage on a daily basis. But they've been recycling for years in Henrico County, turning waste into valuable fuel.

In order to get clean water from sewage you need to take out all the solid stuff, but you can't just throw it away. At the Henrico County Water Reclamation Facility, bacteria does the hard work of cleaning it up.

"This is called anaerobic digestion in the absence of oxygen," said James Grandstaff, Henrico County Water Reclamation.

James Grandstaff says it's happening in four of these huge covered tanks, kept at a constant 98 degrees, the bacteria go to work, literally eating the solids for 30 straight days.

"Stabilize sludge, biosolids, reduces pathogens that exist prior to treatment. So when you go for final disposal you don't have pathogens or vector for disease," Grandstaff said.

But you do end up with a whole lot of methane gas as a byproduct. Instead of releasing methane, a greenhouse gas into the atmosphere, it's burned off in these flares just like at landfills. But not all of it goes to waste. Some is captured and used as a heating fuel.

"We produce 180 million cubic feet per year and we use 40 percent of that to heat our buildings and to heat the contents of the digesters," he said.

It's a clever setup and it saves the county money. The methane replaces 1,200 gallons of fuel oil a day. That's about a $2,400 a day or more than $800,000 a year.

And there may be more savings to come. The county is looking at other ways to use the methane that currently gets burned off. Maybe even as a source of electricity down the road; proving that even raw sewage can be a clean industry.

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