Thickening is the first step for reducing the sludge volume by removal of free sludge water. Thin sludge is concentrated to thick sludge. Thick sludge has a higher viscosity, but must still be pumpable.
Sludge settles in gravity thickeners and is compressed by the weight of its own solids. Due to their higher specific density, primary and digested sludge can be better gravity-thickened than secondary sludge.
Secondary sludge (e.g. waste activated sludge) is preferably thickened mechanically, separate from primary sludge. Polymers are added to the thin sludge for flocculation. Generation of large and strong flocs depends on the right choice and dosage of polymers, and on intensive mixing of polymers and sludge. Sludge water is released between the flocs and drains by gravity through a filter medium (cloth or fine screen) while flocs are retained thereon.
We manufacture various kinds of highly effective HUBER machines for sludge thickening. They are all made of stainless steel and can be distinguished by their design, size and capacity. We offer best-performing equipment for every application: