Gravity thickener for sludge treatment
Graver Water Systems
In the Rota-Rake the water enters a central inlet well where its velocity is reduced. The large laminar flow achieved by the large increase in flow area allows the heavy solids to coalesce and further thicken to settable size. As the water flows evenly and gently from the bottom of the inlet well and makes its way radially across the unit, the lighter solids settle to the bottom where the sludge scraper rolls them toward the center of the unit, further thickenening the sludge in the process.
The effluent water is collected through weirs and the heavy-duty sludge scraper moves the solids with a minimum of agitation to the discharge sump. The arms for the sludge scraper are equipped with angled blades that sweep the entire bottom of the vessel and are driven from a central shaft that is attached to a low rpm speed reducer motor assembly. The arms are also equipped with thickening pickets that extend down into the discharge sump that provide further thickening of the settled floc. This two stage thickening of the sludge permits a relatively high density sludge to be removed from the thickener thereby resulting in a savings in blowdown waste.
