Which process in sludge treatment reduces the volume of sludge sent to the digester?

Thickening is a crucial process in sludge treatment that reduces the volume of sludge before it is sent to the digester. During thickening, water is removed from the sludge, resulting in a higher concentration of solids. This decrease in water content leads to a reduced overall volume, allowing for more efficient handling and processing in the digester.

The primary goal of thickening is to make the sludge more manageable and to enhance the efficiency of subsequent processes like digestion. By concentrating the solid materials, thickening prepares the sludge for the anaerobic digestion process, where microbial action breaks down the organic materials.

In contrast, elutriation typically involves washing the sludge to separate finer particles, which does not contribute to volume reduction overall. Chemical conditioning introduces clarifying agents to improve settling and separation but does not necessarily reduce the sludge volume. Wet oxidation is a more advanced treatment method used for the stabilization of sludge, but it also does not focus on the reduction of sludge volume before digestion as thickening does. Thus, thickening is specifically aimed at minimizing the volume of sludge sent for further treatment.