Filtration is the most widely used method in the treatment of sludge produced by wastewater treatment. It can consist just in drainage though sand beds or it can be mechanical under vacuum middle or high pressure conditions which require more sophisticated equipment.
Filter presses operate applying very high pressures to the cake. Cake from high pressure resistant filter press can be secondarily squeezed under max 1.6 Mpa by water to realize the lowest cake residual moisture. In some wastewater treatment industries, the final cake can be used for landfill or burning directly.