Filter cake washing is an optional processing step in the filter cake post-treatment in combination with the membrane technology. This involves a chemical/physical treatment of the filter cake or replacement of the filtrate still contained in the filter cake with a washing medium. The dewatering properties of the suspension determine the required filtration or washing pressure. In addition, the maximum allowable pressure on the following factors depends on:

• • the permitted operating pressure of the press frame

• • the permitted pressure and temperature load of the membrane filter elements

FUNCTION FILTER CAKE WASHING

The washing medium is introduced during filter cake washing through a washing plate on an inlet side of the filter chambers. The washing medium then penetrates the filter cake within the entire chamber. The wash filtrate, which accumulates in the chamber pressure plate, then runs off through its defined bores. The fluid feed can also be reversed upon request. Optimum washing results are achieved in particular when the flexible membranes are pressurised with primary pressure to stabilise the filter cake during cake washing. The membrane will only be fully effective if the membrane pressure is slightly higher than the washing pressure.