These plants use a layer (precoat) of fossil flour or wood flour as a filtering medium, which is applied on top of a special cloth mounted on a rotating support called a drum. The vacuum between the top and bottom of the drum keeps the precoat on the cloth and allows the suction of the liquid to be filtered.
The precoat layer retains the solid while allowing the liquid to pass through. A steel blade slices through a light layer of precoat at each turn of the drum, knocking off the dried-out dirt and keeping the filter surface clean.
This product is particularly suitable for the recovery of the liquid part of the product.