Recycling sludge stirs questions

Recycling sludge stirs questions

June 13th, 2010 by Pam Sohn in News

In the past three years, Chattanooga has saved taxpayers and farmers money by converting leftover sludge from Moccasin Bend Sewage Treatment Plant into nearly 350,000 tons of biosolids that can serve as fertilizer for crops not eaten by people.

"We call ourselves Chattanooga's No. 1 recycler," plant Superintendent Alice Cannella said.

Most of the biosolids go to farms in Sequatchie, Marion and Bledsoe counties in Tennessee and Jackson County, Ala.

"It's called beneficial reuse," Ms. Cannella said. "With the costs of today's fertilizers, it saves the farmers money because it is high in nitrogen and alkalinity. We give it free to the farmers, and we spread it. It also saves us money because we're not burying it in landfills and using up landfill space."

But questions have been raised nationally about the safety of using biosolids on farm fields, and in Sequatchie County, a petition with 90 signatures prompted county commissioners to pen a resolution in April banning the stuff on fields there.

County Executive Michael Hudson said the resolution hasn't been voted on yet, pending a legal opinion from the University of Tennessee's County Technical Assistance Service.

"We're weighing our options to see whether we have any options," Mr. Hudson said. "It's a state-funded and state-regulated program. ... We're educating ourselves."

BEND BIOSOLIDS

2007

* Tennessee: 108,949 tons

* Alabama: 13,639 tons

2008

* Tennessee: 103,702 tons

* Alabama: 25,495 tons

2009

* Tennessee: 57,468 tons

* Alabama: 37,538 tons

Source: Moccasin Bend Sewage Treatment Plant

SPREADING SLUDGE

In 2009, 95,006 tons of treated sludge from Moccasin Bend Sewage Treatment Plant was placed on farm fields in Tennessee and Alabama.

In Tennessee, that included:

* Hamilton County: 3,891 tons on 488 acres

* Sequatchie County: 21,355 tons on 725 acres

* Marion County: 17,766 tons on 639 acres

* Bledsoe County: 11,693 tons on 419 acres

* Grundy County: 2,762 tons on 221 acres

In Alabama, it included:

* DeKalb County: 2,405 acres on 334 acres

* Jackson County: 26,293 acres on 1,355 acres

Source: Moccasin Bend Sewage Treatment Plant

Environmental and citizens groups have challenged similar programs in other communities, saying the smelly material, though treated with lime to kills organisms, still contains metals and other leftovers from industrial wastewater.

In Tennessee, the waste can be spread only on hay fields or where crops are not grown for human consumption. The hay, however, will be eaten by cattle, which are eaten by humans.

Scientists say many contaminants bioaccumulate -- become concentrated inside the bodies of living things -- and can travel up the food chain.

In Sequatchie County, one farmer spearheaded a challenge..

Lloyd Stewart, of Dunlap, said biosolids spread on a farm adjacent to his smelled so bad his grandchildren were sickened and the family contemplated moving them away.

"Sludge has copper and arsenic and lead in it," he said. "And this is spread on a field beside the river that is a drinking source. (Regulators) say it's soaking into the ground and not running in the river, but shucks, I know it's not all going into the ground."

The Tennessee Department of Environment and Conservation regulates the local biosolids program and requires material not be spread too near houses, wells or water, according to department spokeswoman Tisha Calabrese-Benton.

"EPA has provided guidance on how solids generated in a wastewater treatment plant can be managed," she said.

Sludge must be placed in a landfill, but when the sludge has lime added as a disinfectant, it is transformed into biosolids, she said.

Ms. Cannella said Moccasin Bend biosolids are treated with two processes and stabilized with lime.

"The lime raises the pH to 12, so all the undesirable organisms are killed," she said.