It’s Sweet Smell of Success at Sludge-Conversion Firm : Environment: The Ohio firm’s process allows sewage residue to be changed into fertilizer.

TOLEDO, Ohio —  A sludge treatment company has concocted a way for communities to turn their sewage into, well, not exactly gold, but something akin to pay dirt.

It’s a commercial fertilizer that looks, smells and acts like soil.

Cities have been trying to deal with sludge for decades. Some burn it, others haul it to landfills. A few dumped it in the ocean--a practice that Congress outlawed last year.

“Sludge has always had a bad name. But we’ve developed a process that can turn sludge into something useful,” says Pat Nicholson, president of N-Viro Energy Systems Ltd.

Thirty-three communities in the United States, England and Australia are using the process, in which sludge is treated with lime and cement kiln dust to kill disease-producing bacteria.

The kiln dust removes odor from sludge the same way baking soda absorbs refrigerator smells.

The patented process was developed in 1984 by Nicholson and Jeffrey Burnham, a microbiology professor at the Medical College of Ohio in Toledo. N-Viro began marketing it in 1987.

Last November, N-Viro received the President’s Environmental and Conservation Citation for excellence in innovative technology.

The company builds and operates sludge processing plants for communities. It also sells the technology so municipalities can build and manage their own operations.

Last year, 33 N-Viro plants were operating worldwide, and 30 are expected to open this year.

N-Viro processed more than 1 million tons of sludge last year. Marketed as N-Viro Soil or N-Viro Aglime, most of it was used by farmers. Some was used for land reclamation or landfill cover.

The company eventually plans to sell N-Viro soil for residential use.

N-Viro has been treating Toledo’s sludge since December, 1989. The city generates about 50 tons a day. Before N-Viro, it was spread on farm fields, a practice some communities oppose because of the smell and health risk.

Farmers now ask for the product, which sells for about $5 a ton, says Christopher Mahoney, national sales manager. It is odorless and easily spreadable like other fertilizers.

Donald Romes, Toledo’s utilities project manager, says he is pleased with N-Viro.

“About four years ago, there was nowhere to go with our sludge. Now we have more demand than product. We don’t have to worry about stockpiling it,” he says.

Although communities technically don’t make any money with the N-Viro product, they drastically reduce sludge disposal costs. It costs about $150 a ton to produce N-Viro, compared to as much as $400 a ton to dump it in a landfill and about as much to compost it.

Farmers also cut production costs. A study by William Meyer, an agricultural consultant, showed that N-Viro Soil can reduce farmers’ expenses by up to $40 an acre, depending on the crop.

John Walker, a physical scientist with the EPA in Washington, said N-Viro is one of the best sludge products. But he said local officials should examine the various processes before deciding which is best for their community.

“Each of these form a different kind of end product, which is used differently,” he said.

The city of Milwaukee about 70 years ago created a sludge byproduct called Milorganite. The sludge is burned at a high temperature, creating a small pellet that can be used as a fertilizer.

The method, however, destroys much of the bacteria needed to control odor and enrich crops. It also costs up to $700 a ton to make.

Terry Ward, spokesman for the Milwaukee Metropolitan Sewage District’s Milorganite division, said the city produces 45,000 to 60,000 tons of Milorganite a year. It is marketed worldwide as fertilizer for golf courses and gardens.

He said he is familiar with the N-Viro process. But he believes that Milorganite may be better for lawns because it contains more iron.

“We applaud everyone who is coming into this particular venue, and we say that anyone coming into this is doing the right thing,” Ward said.