Thickening
Thickening is the process of increasing the solids content of sludge and involves the removal of excess water by decanting as well as the concentration of solids by settling. Decanted water is usually recovered, while the solids are processed further or are disposed of.

Filter Presses & Belt Presses
Filter presses are used for dewatering sludges and to increase the amount of water recovery from the dewatering process. Filter press dewatering is achieved by forcing the water from the sludge at high pressure. The filter press unit consists of a number of plates or trays, each with a filter cloth, supported in a common frame. During sludge dewatering, these frames are pressed together forcing the liquid through the filter cloth and plate outlet. The plates are then separated and the sludge removed. With a belt press, the sludge is pressed between a continuous two-filter belt and roller system.

Centrifuges
Centrifugation is a separation process that thickens and dewaters sludges via the action of centrifugal force, thereby promoting accelerated settling of the particles in a solid-liquid mixture. Centrifuges are normally used in the dewatering of lime-softening sludges and for sludge thickening or dewatering.