Principle
Gravity thickening is the easiest way to thicken sludge. An example of a gravity based sludge thickener is the Dortmund Tank. This type of sludge thickener, very similar to a clarifier, may be applied either continuously or in batch. The water that flows over the overflow edge of the sludge thickener is returned to the purification process while the thickened sludge can be pumped to a dewatering. Other design possibilities are the lamella seperator and the flotation.
An important parameter for the design of a sludge thickener is the load of dry matter per unit area, usually expressed in kg dry matter / m² day. The guide values of the solids load vary with the type of sludge (primary sludge, activated sludge, sludge from biofilters, thermally conditioned sludge, ...). The expected dry matter content of the thickened sludge is also affected by the type of sludge, and thus can vary from 3 to 15% dry matter.
Scheme
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Applications
Production processes were waste sludge is generated
Primary pretreatment
Example of realisation
