Since 1995, the Florida city of Vero Beach used Jones and Attwood twin rotary drum thickeners (Ovivo USA) and two aerobic digesters to store 2 percent liquid biosolids. Ranchers and farmers applied 6.5 million gallons annually.
By 2010, watershed restrictions had reduced the agricultural sites available. City officials hired a contractor with a portable centrifuge to dewater and landfill the material. “We’d run a 400,000-gallon batch through the rotary drum thickener whenever the contractor arrived, which was monthly in summer and every three weeks during the three-month winter tourist season,” says Rob Bolton, director of the city’s Water and Sewer Department.
