Apparatus for static membrane filtration

In a filtration apparatus for static membrane filtration of liquids, including an outer vessel comprising a centrifuge tube containing a liquid medium to be filtered, and having an open top and a closed bottom, and a filter unit provided with a filter element disposed in the liquid medium within said tube, the medium to be filtered being under excess pressure and in contact with said filter element of the filter unit, the improvement which comprises the filter unit having means defining an open upper end and a portion thereof at said upper end is reduced in wall thickness for storing rising liquid medium, means defining an unsealed gap or clearance situated between the filter unit and said centrifuge tube, and a filter membrane being disposed on the outside of the filter unit facing the bottom of said tube, the membrane having an edge and being sealed around said edge, and having a filtration active layer pointing outwardly thereof for filtering the medium so as to allow a filtrate thereof to collect in the filter unit.