April 4, 2013
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A city of Delaware truck delivers sludge to Ringler Energy in Cardington. The city has changed how it disposes of sludge from the wastewater treatment plant.
The city of Delaware has changed how it disposes of its sludge, so now it gets used as energy instead of going to waste.
“We spent approximately $250,000 a year disposing of our sludge, and having it just go to a landfill with no beneficial re-use,” said Brad Stanton, director of public utilities, at the Public Works/Public Utilities Committee meeting April 2.
Sludge is the solid matter produced in wastewater treatment processes. It is defined by the Environmental Protection Agency as a pollutant. According to the city, Delaware transported 6,250 wet tons of sludge in 2012.
Stanton said for the last couple of weeks, the sludge has been hauled twice a day to a bio-gas facility in Cardington built operated by Quasar Energy and used by Ringler Energy.
“We recently entered into a contract with Quasar Energy out of Cleveland,” Stanton said. “They take (Ringler’s) hog waste and now our sludge, and anaerobically digest it. Through the anaerobic digestion process, methane is produced, then converted into electricity or natural gas.”
Anaerobic digestion is described as a natural process that farmers have used for years. The “digester” tanks contain bacteria that thrive without oxygen. The microorganisms are fed are organic waste, and their digestion produces methane.
“(Anaerobic digestion) was a popular technology over in Europe and now it’s finally getting over to the States,” Stanton said. “It’s really green and beneficial.”
Stanton told the committee, “We discussed building one of these facilities on Cherry Street, but did not have the biomass necessary to make it financially beneficial, so we’re hauling the waste to the farms.” Biomass can consist of agricultural manure, crop waste, alcohol and ethanol byproducts, food waste, and sludge.
The city said the energy produced from the sludge as electricity to heat Ringler’s livestock pens and farm buildings, and as natural gas for its truck fleet.
Stanton said switching its disposal will save Delaware money in landfill tipping fees. In addition, the drive to Cardington is 20 miles instead of 46 miles to the Bellefontaine landfill.
However, in a few weeks, Ringler will be picking up Delaware’s sludge.
“Eventually, they will haul it, and they will use their vehicles to travel from Cardington in Morrow County to our facility, fill up, and drive it back,” said Lee Yoakum, city community affairs coordinator. “Right now, we are hauling it because our intake area at the wastewater plant is not configured for a tractor-trailer. We’re actually doing that work right now to modify the discharge area.”
The city said it will pay Ringler $35 per ton for hauling and digesting, which is a $9 per ton savings from 2012. The city said it expects to save $55,000 a year.
“It’s a win-win for our residents in that we’re saving money in disposing of this byproduct, and we’re helping the environment at the same time,” Yoakum said.
Representatives from Ringler and Quasar did not return calls from The Gazette seeking comment.