Filter presses are sometimes called “Plate-and-Frame Filters” which describes the style of filters developed from the 1800’s onwards. The majority of today’s filters are more correctly called “Membrane Plate Filters”.

Many processes in the food, chemical or pharmaceutical industries make products that are liquid-solid suspensions or slurries. These mixtures are a little like a runny mud or Milk-shake. The solids in them do not dissolve in the liquid but are carried along in it. Filter presses separate the solids from the liquids so that the useful part can be
processed or packaged.

Filter presses generally work in a “batch” manner. They are loaded with slurry before completing a filtering cycle and producing a batch of solid filtered material, called the filter “cake”. The solid is removed, the press re-loaded with slurry and the batch cycle repeated.

A filter press uses increased pressure to maximise the rate of filtration and produce a final solid with a low water content. This is more efficient than filtration using a funnel and paper which utilises the low pressure caused by the weight of liquid above the filter paper.