Mechanical sludge disintegration is categorized into different types, such as stirred ball milling, lysis-thickening centrifuge, high-pressure homogenizer (HPH), ultrasonication, high-pressure jet and collision and rotor-stator disintegration. These treatments are applied on secondary sludge or mixtures of primary and secondary sludges. Stirred Ball Milling occurs in a cylindrical grinding chamber equipped with a central rotating shaft. Beads are put into the chamber to provide more shear force for sludge disintegration. Lysis-Thickening Centrifuge is designed based on a thickening centrifuge machine. Additional cutting blades are installed in the rotating shaft for sludge disintegration. High-Pressure Homogenizer is an alternative mechanical treatment technology. The major principle of HPH relies on abrupt pressure gradient, high turbulence, cavitation as well as strong shearing forces, which are aroused under the strong depressurization of highly compressed sludge suspensions. Electrokinetic disintegration, as a newly developed sludge pre-treatment technology, has been extensively implemented in industry.