METHOD AND DEVICE FOR MEMBRANE FILTRATION (VERSIONS) Russian patent published in 2002 - IPC

FIELD: cold sterilization of drinks and drugs, clarification of juices, wines and beer, plasmapheresis, concentration of cells, treatment of sewage water, preparation of clean water. SUBSTANCE: filtration is performed from flow of solution perpendicularly to direction of transport on rigid semi-permeable ceramic membranes of high porosity. Specific feature of this method is avoidance of formation of helium layer on membrane surface during entire filtration process; filtration shall be combined with alternating sign transmembrane pressure and directive flows of liquid being filtered. At positive transmembrane pressure, liquid being filtered moves along surface of membrane and filtrate is removed outside; at negative transmembrane pressure, part of filtrate (no more than 20%) is returned through membrane pores, thus cleaning them from stuck particles; subsequent flow of liquid being filtered is mixed with these particles when positive transmembrane pressure is created again and filtration is carried out on clean membranes. Device proposed for realization of this method includes filter-piston reciprocating in rigid housing owing to three valves of unidirectional flow, two elastic tight membranes, two spacer rings and other structural features. According to second version, membrane filter is made in form of rigid structure fixed in housing. Filter may consist of one porous semi-permeable cylinder or cassettes from several semi-permeable tubes of small diameter. For creating the pulsating transmembrane pressure, use is made of membrane-type piston which is reciprocating by means of solenoid. Solenoid may be also used for reciprocating of filter-piston. It is good practice to use floating or immovable units for forming required working clearance along membrane surface when rigidly secured membrane filter is used. EFFECT: avoidance of sticking of membranes with no reduction of their throughput and change of their characteristics. 15 cl, 7 dwg