This chapter provides an in-depth discussion of sludge thickening equipment in the context of water and wastewater treatment. It begins by outlining the definition and primary purpose of sludge thickening, along with current development trends in China and worldwide. The chapter then details major methods of sludge thickening, including gravity thickening, air flotation thickening, and centrifugal thickening, highlighting their advantages and disadvantages through comparative tables. Procedures for safe operation are described, with a particular focus on operating steps and routine maintenance for belt sludge thickeners. Finally, the chapter addresses common faults and troubleshooting methods, such as frequent deviation of the belt thickener cloth, severe mud runoff, cloth blockage, premature aging, and coagulant pump issues, providing practical solutions to ensure efficient and reliable operation.