'Biosolids' plant takes stink out of sludge
Pellets to be used for fertilizer
By MICHAEL CASS • Staff Writer • May 4, 2008
The things you flush down your toilet could feed someone's lawn before summer's over.
Metro Water Services is running the final tests before it opens a new waste-water treatment facility on Second Avenue North. The $125 million Central Biosolids Facility will convert waste water produced by Metro residents and businesses into tiny pellets that can be used as fertilizer.
About 70 tons of pellets, known as "biosolids," will replace the 350 tons of treated sludge the city has been sending off to landfills every day. The stench that has sometimes annoyed residents of nearby Germantown and Salemtown also should be eliminated, Metro officials said. The city spent $10 million on odor control.
"Salemtown and Germantown continue to develop, so we had to do something," said Ron Taylor, chief engineer for the water department's operations division.
"To go from having to send all that material to landfills and sending a lot of trucks through developing neighborhoods to a point where we'll cut the trucks by 75 percent, that is a transformation."
But the biosolids project still makes some people queasy.
Some environmental activists say Metro is essentially taking sludge that would go to landfills and putting it on soil, where it could hurt animals and people.
" 'Biosolids' is just a pretty name the industry gives sludge," said Sherry Force, who runs a recycling and environmental awareness program at Granbery Elementary School. "We should continue to landfill it until we find a safe way to dispose of it.
"These people do not know what's in this material at any given time, yet they've sanctioned it to be spread out on agricultural fields."
Taylor said the Metro treatment process will eliminate disease-causing pathogens found in the sludge, however, and produce a safe, nutrient-rich class of pellets. The process meets the U.S. Environmental Protection Agency's standards for reuse of waste water.
But the EPA's blessing doesn't mean much to Force or fellow activist Bruce Wood.
"Maybe the federal government lets us get away with it, but they let us pollute the Cumberland River, too," said Wood, who leads a Nashville environmental and public health advocacy group called BURNT.
More sewage processed
The number of Metro sewer customers has increased about 15 percent in the past seven years, Water Services Director Scott Potter said at a Metro Council budget hearing last month. Taylor said Metro has been sending about 100,000 tons of sludge a year to landfills at a cost of about $3 million annually.
That will change under the biosolids process, which will take the residual sludge produced by the older waste-water treatment process — the smelly gunk now going to landfills — and break it down further.
The new facility will thicken the residual sludge to start removing water and use anaerobic bacteria — bacteria that don't need oxygen — to reduce pathogens and decompose the sludge. That part of the process, which takes place in large buildings called "digesters," produces methane gas.
The digested sludge then will go to one of five centrifuges, which will "dewater" it to remove excess liquid. Finally, it will go through a heat-drying system, powered by the methane gas from the digesters, to evaporate the remaining water, destroy the remaining pathogens and produce the biosolids.
The pellets will be heated to 200 degrees Fahrenheit when the process is over.
Metro has contracted with Arkansas-based Mannco Fertilizer Co. to market 25,000 to 30,000 tons of pellets a year, according to the company's Web site.
"Mannco has successfully developed markets for use on row crops, golf courses, horticulture and turf grass needs," the Web site says.
Jeff Gossage, Metro's purchasing director, said Friday that the marketing contract had been awarded but did not call back with details.
Greenway planned
Metro also is planning to build a greenway near the biosolids facility, said Shain Dennison, greenways director for Metro Parks. Construction could start this summer on the 1.5-mile stretch, which would be part of a greenway system connecting downtown to MetroCenter and would feature a spur to Germantown's Morgan Park.
"It's going to be a better thing when they get everything done," said Salemtown resident and blogger Mike Byrd, who has complained about the smell coming from the waste-water treatment plant in the past. "All the dominoes seem to be falling into place. … It's a great thing for Salemtown."
Metro also has built a smaller, $25 million biosolids facility at its Dry Creek waste-water treatment plant in the Rivergate area. The Dry Creek plant opened in 1961, three years after the Central plant opened north of downtown.
http://tennessean.com/apps/pbcs.dll/article?AID=/20080504/NEWS01/805040428/-1/ARCHIVE01
Pellets to be used for fertilizer
By MICHAEL CASS • Staff Writer • May 4, 2008
The things you flush down your toilet could feed someone's lawn before summer's over.
Metro Water Services is running the final tests before it opens a new waste-water treatment facility on Second Avenue North. The $125 million Central Biosolids Facility will convert waste water produced by Metro residents and businesses into tiny pellets that can be used as fertilizer.
About 70 tons of pellets, known as "biosolids," will replace the 350 tons of treated sludge the city has been sending off to landfills every day. The stench that has sometimes annoyed residents of nearby Germantown and Salemtown also should be eliminated, Metro officials said. The city spent $10 million on odor control.
"Salemtown and Germantown continue to develop, so we had to do something," said Ron Taylor, chief engineer for the water department's operations division.
"To go from having to send all that material to landfills and sending a lot of trucks through developing neighborhoods to a point where we'll cut the trucks by 75 percent, that is a transformation."
But the biosolids project still makes some people queasy.
Some environmental activists say Metro is essentially taking sludge that would go to landfills and putting it on soil, where it could hurt animals and people.
" 'Biosolids' is just a pretty name the industry gives sludge," said Sherry Force, who runs a recycling and environmental awareness program at Granbery Elementary School. "We should continue to landfill it until we find a safe way to dispose of it.
"These people do not know what's in this material at any given time, yet they've sanctioned it to be spread out on agricultural fields."
Taylor said the Metro treatment process will eliminate disease-causing pathogens found in the sludge, however, and produce a safe, nutrient-rich class of pellets. The process meets the U.S. Environmental Protection Agency's standards for reuse of waste water.
But the EPA's blessing doesn't mean much to Force or fellow activist Bruce Wood.
"Maybe the federal government lets us get away with it, but they let us pollute the Cumberland River, too," said Wood, who leads a Nashville environmental and public health advocacy group called BURNT.
More sewage processed
The number of Metro sewer customers has increased about 15 percent in the past seven years, Water Services Director Scott Potter said at a Metro Council budget hearing last month. Taylor said Metro has been sending about 100,000 tons of sludge a year to landfills at a cost of about $3 million annually.
That will change under the biosolids process, which will take the residual sludge produced by the older waste-water treatment process — the smelly gunk now going to landfills — and break it down further.
The new facility will thicken the residual sludge to start removing water and use anaerobic bacteria — bacteria that don't need oxygen — to reduce pathogens and decompose the sludge. That part of the process, which takes place in large buildings called "digesters," produces methane gas.
The digested sludge then will go to one of five centrifuges, which will "dewater" it to remove excess liquid. Finally, it will go through a heat-drying system, powered by the methane gas from the digesters, to evaporate the remaining water, destroy the remaining pathogens and produce the biosolids.
The pellets will be heated to 200 degrees Fahrenheit when the process is over.
Metro has contracted with Arkansas-based Mannco Fertilizer Co. to market 25,000 to 30,000 tons of pellets a year, according to the company's Web site.
"Mannco has successfully developed markets for use on row crops, golf courses, horticulture and turf grass needs," the Web site says.
Jeff Gossage, Metro's purchasing director, said Friday that the marketing contract had been awarded but did not call back with details.
Greenway planned
Metro also is planning to build a greenway near the biosolids facility, said Shain Dennison, greenways director for Metro Parks. Construction could start this summer on the 1.5-mile stretch, which would be part of a greenway system connecting downtown to MetroCenter and would feature a spur to Germantown's Morgan Park.
"It's going to be a better thing when they get everything done," said Salemtown resident and blogger Mike Byrd, who has complained about the smell coming from the waste-water treatment plant in the past. "All the dominoes seem to be falling into place. … It's a great thing for Salemtown."
Metro also has built a smaller, $25 million biosolids facility at its Dry Creek waste-water treatment plant in the Rivergate area. The Dry Creek plant opened in 1961, three years after the Central plant opened north of downtown.
http://tennessean.com/apps/pbcs.dll/article?AID=/20080504/NEWS01/805040428/-1/ARCHIVE01
posted by Sludge at 7:48 AM
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