The press filter is a device whose objective is to separate the liquids from the solids contained in a sludge, usually from a physical-chemical decanter through a pressure filtration (from 5 to 15 bars or more). 

The press filter is characterized for being a simple and reliable method to achieve high compaction because they are capable of compressing and dehydrating solids to obtain 25% to 60% of weight of all the compacted sludge.