Thickened sludge retains the free-flowing liquid-like properties of sludge. Sludge consolidation processes can be categorised as either thickening or dewatering, depending on the extent of water removal.

destruction, in which the organic carbon component of the sludge is either oxidised, ultimately to carbon dioxide, or reduced, predominantly to methane.consolidation, which reduces the sludge volume by removing the water along with the associated dissolved solids, and.There are essentially two methods by which the volume of sludge is reduced: These solids are referred to as biosolids and can be used as soil fertilisers or else their latent energy recovered by conversion to heat or a useful fuel (or biofuel). The organic solids component of the sludge, quantified as the volatile solids (VS) content, is normally considered to be the most directly useful. The suspended solids normally make up 2−5% of the sludge for municipal wastewater sludge. Regardless of its origins, sludge contains water, dissolved organic and inorganic materials and suspended solids. the secondary biological treatment stage, producing waste activated sludge (WAS) if the biological treatment is based on the activated sludge process.from the primary sedimentation stage, producing primary sludge, and.For conventional municipal wastewater treatment, the two principal sludge streams are: The sludge characteristics depend on both the original feedwater quality and the type of the unit operation from which the sludge is discharged. its instability, such as the leaching of toxic or otherwise harmful components.the risk it poses to public health, primarily from the pathogenic micro-organism content,.its volume, and so the cost of subsequent haulage and disposal,.Sludge is the main waste stream generated from water purification, both water for drinking and wastewater for environmental discharge.

Sludge in wastewater treatment