BROOKSVILLE — It's hauled around on a trailer, performs an important if unsavory function, and should help to curtail residents' complaints about foul odors in their neighborhoods.
It also costs more than a half-million dollars, but county staff insists it will pay for itself in several ways.
The new centrifuge that County Commissioners agreed on Tuesday to buy for $558,000 will be hauled from one county wastewater treatment plant to another to perform its essential, if malodorous, mission.
Spinning at high speeds, the centrifuge will remove liquids from the more than 8-million gallons of so-called "bio-solids'' that are left over each year after Hernando County's sewage has been treated at the plants.
For many years, the treated slurry from the plants has been trucked away and spread over open fields around the county. Now, these bio-solids that will be spun through the centrifuge will become a thick sludge that can be dumped at the county landfill. Officials estimate they will create about 1,200 tons of the stuff annually.
County utilities director Joseph Stapf said this is a welcome alternative for a few reasons.
First, it should stop most of the complaints from residents about the smells associated with the spread of treated sewage (more on that later).
Plus, the sludge is in high demand at landfills because it speeds up the breakdown of other materials dumped there. It also produces methane gas, which is marketable, Stapf said.
Commissioners had balked at the steep price of the centrifuge, especially during these dire economic times, but Stapf said the machine would save at least $121,000 per year, noting it would cut down on transportation costs by not having to haul the slurry far out in the country to spread on fields.
The cost of the centrifuge comes from the utilities budget, which is supported through user fees, not the general fund property tax dollars.
When sludge is prepared for spreading on rural land, it is treated with lime, which produces many of the pungent odors associated with sewage treatment plants. The centrifuge would cut out this step.
"It isn't going to eliminate the odor issue entirely but it is going to eliminate a source of odor,'' Stapf said.
Another plus, he said, is that the public should stop complaining that the county is spreading toxic waste on the ground and putting residents at risk. Stapf said people who smell the treated sewage assume the material is toxic, even though it is safe.
"That's always a concern among people who live around an area where it's been applied,'' he said. "People think that if it smells bad, it is bad.''
He said that the practice really is falling out of favor. "I personally do not believe that land application of bio-solids is long for this world,'' he said.
County commissioners this week also granted a $1.57-million price increase in the contract the Utilities Department has with the engineering firm designing the major sewage treatment improvements on the horizon.
After the firm began work, it was determined that a planned $10-million replacement for the Spring Hill Wastewater Treatment Plant would cost more that $25-million.
County officials decided to return to another plan that will shift sewage to the plant at the county airport and close the Spring Hill plant.
Design of an airport plant with a larger capacity, larger sewer lines, a reuse line from the airport plant back to the golf course at Timber Pines and other tasks were all added to the scope of work for the firm, TBE Group, Inc. The original cost of this plan was $3.6-million.
Barbara Behrendt can be reached at firstname.lastname@example.org or (352) 848-1434.