Thickening

Thickening is the practice of increasing the solid content of sludge by the removal of a portion of its liquid content. A modest increase in solids content (from 3 to 6%) can decrease total sludge volume significantly (by 50%), entailing reduced size requirements for subsequent treatment units. Sludge thickening methods are usually physical in nature: they include gravity settling, flotation, centrifugation and gravity belts.