Compositech's gravity belt thickening equipment employs the forces of gravity for filtration in order to allow liquid to drain from the sludge through a single woven cloth filter belt. Initially, the liquid sludge is conditioned by adding polymers to obtain a separation between the liquid phase and the solid phase. Once flocculated, the sludge passes through the feeding box onto the synthetic belt supported by a high-density polyethylene (HDPE) grid which is supported by a stainless steel framework. The free water is separated by a combination of gravity and atmospheric pressure. In addition to supporting the gravity belt thickener, the HDPE grids break the surface tension on the underside of the filter media and encourage the free-standing water to drain through and be collected in a drain pan below, while the filtered solids remain on top of the filter belt. A series of special plows continuously turn, push, compress, and distribute the sludge across the width of the belt, allowing for optimal drainage of liquids. The thickened sludge is removed from the separator belts by a doctor blade mounted at the discharge end of the thickener. At this point, the sludge can be easily pumped to the next stage of de-watering or disposal. Cleaning of the gravity concentration belt is accomplished by belt washing stations containing a pipe with nozzles where pressurized water is sprayed through the filtering surface. A pneumatic system provides for tensioning and the automatic centering of the gravity belt thickener.