Sludge conditioning
An overview of sludge conditioning − chemical and thermal
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Chemical conditioning through reagent dosing is designed to coalesce (or agglomerate) the smaller sludge particles (1−10 µm) to produce larger ones, and to reduce the colloidal (the sub-0.1 µm particle/macromolecular size range) content of the particulate matter. This then increases both the particle sedimentation rate and the permeability of the cake − the solids sediment formed from the particles. In doing so, the efficiency of the downstream thickening and dewatering processes is increased.
An overview of sludge conditioning − chemical and thermal
Thickening and dewatering processes often need pre-treatment (conditioning) to help separate the water from the solids
The chemical pre-treatment of sludge helps remove water upstream of thickening and dewatering processes
Conditioning is the pretreatment of sludge upstream of thickening and dewatering to promote solid-liquid separation
Thickening processes concentrate the sludge by removing part of the free water, such that the product can still be pumped
Dewatering processes mechanically remove a significant proportion of the sludge water to produce a 15-45% cake product
In sludge drying the sludge moisture is removed as water vapour by heating, generating a pelleted or powdered product
Sludge stabilisation − alkaline stabilisation, lime and solids dosing, plus anaerobic and aerobic digestion
Thermochemical methods are used to either significantly reduce the sludge solids content or pre-treat sludge upstream of AD
Sludge is the main waste stream from the treatment of wastewater