City Explores Switching to Microwave System at the Wastewater Treatment Plant

Urbana Sludge Being Loaded into Microwave

Assistant Editor
Urbana Daily Citizen - Urbana, Ohio

January 11, 2007

Urbana consultant Dave Stewart said recommending the city switch from the N-Viro system to the microwave system at the wastewater treatment plant is a "slam dunk."

"It's one of those easy recommendations," said Stewart, an employee of Wilbur Smith and Associates and a longtime treatment plant consultant for the city.

Using the N-Viro method of treating sludge costs the city an estimated $250,000 a year, Stewart estimated, adding the necessary purchase of lime is nearly $100,000 of this cost.

With the microwave system, he said, the city would save that annual $100,000 cost.

"The savings would pay for the unit," Urbana Director of Administration Bruce Evilsizor said.

Purchasing the unit and rehabing a building at the treatment plant is estimated to cost $1.5 million, Stewart said. He agreed money saved by switching to the microwave system would exceed the cost of paying for it.

Plant Superintendent Chad Hall also says microwave is the way to go.

"I thought it was absolutely amazing," he said of observing the process in Fredericktown, just north of Columbus.

Hall said that besides saving the city money, the microwave system would simplify plant operations and maintenance.

Less storage space required

Hall said a big factor is that the microwave system creates a smaller product than the current N-Viro system.

Whereas, the N-Viro method produced 2,284 tons of sludge cake to be hauled and applied as fertilizer to 571 acres of farmland in 2005, the microwave system would have produced 306 tons of cake that could be applied to 76 acres.

Reducing the amount of resulting fertilizer is considered important since the Environmental Protection Agency is requiring six-month storage capacity rather than the former three-month capacity and since there are restrictions about when the fertilizer can be applied to farmland,

Stewart said the N-Viro method was good in its time, that re-using bio-solids as fertilizer is preferable to hauling it to landfills.

Now, he said, there is something better than N-Viro.

He said the microwave goal basically is the same as the N-Viro goal, heating and pasteurizing sludge so it can be re-used as fertilizer.

Mike Burch of Burch BioWave Inc., the company that created the microwave system, said the microwaves dry the material from the inside out, removing liquid and pathogens, but retaining nutrients beneficial for fertilizer.

A portable microwave demo unit has been at the Urbana plant since just before Christmas to give government and industry representatives in Champaign and other area counties a chance to observe this relatively new method.

Hall said people from Logan, Miami, Shelby and Greene counties are scheduled to visit while the demo unit is here.

Created by Burch BioWave Inc. in Fredericktown, the microwave system has been in operation in that community over two years. A private company in Rosecommon, Ireland, has used the system to handle sludge from nearby communities for 19 months. And, Zanesville is switching to the microwave method this month.

If approved by the city council, Urbana will be the fourth purchaser of such a microwave unit, which would be manufactured in New Hampshire reportedly in about a four-month time frame.

Stewart said the system takes a lot of electricity and that operating the demo unit here should indicate how much it will take.

"We know (the system) will save the city money. We don't know how much," he said.

Burch said the company may soon have representatives in Florida and in Colorado to promote the patented system, which is approved by the U.S. Environmental Protection Agency.

Loaded Microwave Belt before Processing

Processed Sludge Material Exiting the Microwave