Case Study: Centrifuges Solve Problem of Increasing Flows And Decreasing Land

Challenge
The Florida panhandle is booming, especially scenic Walton County, the sixth fastest growing county in Florida. Also booming are the challenges for Regional Utilities of Walton County. The utility runs the water supply system, sanitary sewer collection system and the three activated sludge wastewater treatment plants that serve the county's southern region.

Now, due to the growing population, wastewater flow rates have increased by 15% each year in recent years causing the utility to struggle to keep up with drying and disposing of its digested sludge.

Walton County's continual growth places a large burden on the treatment plants, especially their sludge drying beds. A couple of days of rain would put them way behind.

Solution
Why not add more drying beds? Regional Utilities looked at that option but decided against it because:

• Cleaning sand beds is labor intensive, mostly cleaned by hand.
• Rain is a continual problem, especially in the summer.
• The main consideration was simply the amount of land required for more drying beds - in a place where an acre of land can cost $6 million.

They also considered land applying their sludge, but they would have been paying to haul 98% water.

After looking at all of the options Regional Utilities found their answer: one centrifuge and its building takes up less space than half of one drying bed.

As part of their upgrade, Regional Utilities ordered three skid-mounted Centrapac centrifuge dewatering systems. The Centrapac system is completely prefabricated and pre-engineered for operation. After initial set up, the centrifuge automatically adjusts to achieve maximum cake solids.

Regional Utilities had looked at several different centrifuges but chose USFilter because they wanted the whole package and a company they knew would take care of them.

Results
After nearly one year of operation, the Centrapac system operates 3-4 days a week for 8-10 hours at a time. They feed the sludge between 65 to 75 gpm and are able to achieve 18% dry solids. It couldn't be easier -- it's all automated. The operators turn it on and walk away.

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SOURCE: Siemens Industry, Inc. - Water Technologies