Device could dry, sweeten sludge
Imagine a washing machine on spin cycle, and you have a mental image of a new, $270,000 device that should make things smell sweeter at Nevada County’s Lake Wildwood sewage treatment plant.
Nevada County supervisors are expected Tuesday to approve purchase of a centrifugal sludge thickener for the plant.
It’s basically a big drum that spins around after it’s filled with sewage sludge – solid material from the treatment process – and dries the sludge like a washing machine’s spin cycle squeezes water out of clothes.
There should be less odor once the sludge dryer is installed, said Michael Hill-Weld, director of Nevada County’s Department of Sanitation and Transportation.
Currently, sludge is laid out in drying beds in the sun before it is trucked away to a landfill or used to fertilize a non-food, agricultural crop, such as cotton in Kern County.
“It’ll be a faster way of drying it, (with) less odor,” Hill-Weld said. “As the area around the plant has developed … the impact of the odor … has had more of an effect.”
Another advantage of the centrifugal sludge dryer is that it removes more water from sludge than the solar drying beds do, which should make the sludge cheaper to ship.
The county pays to have sludge trucked to a landfill or to be used elsewhere as fertilizer, Hill-Weld said. So another thing county officials are looking at is possibly finding a market for sewage sludge.
“What we’re looking to do is turn it into a resource,” Hill-Weld said.
A potential way of doing that might be to mix dried sludge with yard waste at the McCourtney Road Transfer Station to produce compost, he said.
Organic gardening expert “Amigo Bob” Contisano will talk to county officials about possible markets for compost from the transfer station. Contisano will speak at 1 p.m. Thursday in the Transportation Department conference room of Rood Administrative Center.
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