Dewatering sludge at wastewater treatment plants has traditionally been a major operational concern. Most large operations must use mechanical filter presses or centrifuges to efficiently dewater their sludge. For many smaller operations, however, this equipment is too expensive and too large for their needs. Therefore, many smaller facilities rely on the sand filter drying beds for sludge dewatering. Removing dried sludge from sand filter drying beds can be a problem because small tractors or loaders cannot be operated on the loose sands of a conventional drying bed. Because of this, the methods used in the past for cleaning the beds have included hand labor and various forms of mechanical devices which are not directly supported by the sand structure.
In Florida, the Sarasota County - Solid Waste Operations Division (SC-SW0) had a problem with their mixed-media, vacuum sludge-drying beds which are used to dewater chemically oxidized septage sludge. The material used for the fixed media would deteriorate under constant use and replacement was very expensive. The SC-SW0 preferred to continue its practice of running a small tractor onto the drying bed to remove the sludge, keeping labor, and time for cleaning and sludge removal to a minimum. However, a solution had to be found that would allow the SC-SW0 to operate their small tractor on top of the sand filter bed and use a front load bucket to remove the sludge.