We are talking about filter presses with squeezing (squeezing) for all those processes and machines that install a mixed plate pack (companion + membranes) or full membranes.

Usually, the membrane plates are chosen in these occasions:

– The sludge to be dehydrated has characteristics for which pressure filtration by pump is only possible up to 6-7 bar. Beyond this limit the pump is not able to increase the pressure. Therefore, if you want to obtain a cake with a high percentage of dry solids also with this sludge, it is necessary to use squeezing.

–The noble part of the filtration process is the filtrate and it is necessary to recover as much of it as possible. This is, for example, the case of the filtration of sludge from the processing of sugar beet or sugar cane.
In this case the squeezing is combined with washing the cake in such a way as to recover as much sugary substance as possible.

-It is necessary to eliminate contaminants present in the sludge. Also, in this case the squeezing is combined with the washing of the cake.

The squeezing process therefore involves sending a fluid under pressure at 15 bar (usually water, but also compressed air) into the interspace between the flexible element of the plates (the membrane) and the rear rigid support.

The swelling of the plates then causes the cake to squeeze/squeeze further dehydrating the sludge. The filtration cycle could therefore for example be:

PRESSING AT 7 BAR – CAKE WASHING – SQUEEZING – CAKE DRYING