Sludge Conditioners are the chemicals or substances added to a suspension to promote and strengthen flocs prior to thickening or dewatering processes. Although some sludge will «flocculate naturally» (e.g. activated sludge) or be delivered by the flocculation treatment stage , it still has too high a resistance to filtration and too high a compressibility factor to guarantee proper water/matter separation and make it possible to use the various dewatering units.
This is the purpose of conditioning, a step that uses chemical type processes (adding mineral reagents or synthetic polymers) and, occasionally, physical type processes (heat).
Therefore, adequate sludge conditioning forms the basis of satisfactory dewatering unit operation: it is used to attain the objectives set in terms of final dry solids content, recovery and operating costs.