Patent TW-400245-B (TW)
Title: Method for regenerating a filtration aid and method for filtering a liquid carrying organic impurities
Inventor: RAHIER GEORGES
IPC: B01J20/34
Filed: 1996-06-01
Granted: 2000-08-01
Abstract: A method for regenerating a filtration aid made of natural or synthetic polymeric grains which are incompressible when subjected to filtration pressure, which have a sphericity coefficient in the range from about 0.6 to about 0.9, which have an average grain size in the range from about 20 mu m to about 70 mu m, which are adapted to form a filter cake having a porosity in the range from about 0.4 to about 0.8 and a density in the range from about 1000 kg/m<3>, said filtration aid being adapted to be mixed with a liquid carrying organic impurities which are essentially comprised of yeasts and to be deposited together and mixed with said impurities on a filtration medium of a filtration installation after filtering said liquid, thereby forming on said filtration medium a filtration mass comprising the filtration aid grains charged with said organic impurities which are trapped in the cavities between the filtration aid grains, wherein said method comprises the following steps : (a) washing said filtration mass by means of a caustic soda solution with a concentration in the range from about 2% to about 5%, at a temperature of at least 80 DEG C, during a time period in the range from about 60 minutes to about 120 minutes, said washing step being carried out in situ in the filtration installation without demounting said filtration mass; (b) carrying out after step (a) an intermediary step consisting in adjusting the filtration mass temperature between 40 DEG C, and 60 DEG C and the filtration mass Ph between 5 and 6; (c) after step (b), in situ washing of the filtration mass in the filtration installation by means of an enzymatic composition at a temperature in the range from about 40 DEG C to about 60 DEG C during a period of time in the range from about 100 minutes to about 200 minutes, said enzymatic composition being essentially comprised of agents capable of lysing yeasts; (d) after step (c), carrying out an additional step consisting in a second washing by means of a soda solution in order to eliminate the waste products produced during the enzymatic treatment step (c), the size of said waste products having been reduced sufficiently to make possible said elimination. A method for filtering a liquid carrying organic impurities which are essentially comprised of yeasts by means of an alluvial filtration process, using a filtration aid made of natural or synthetic polymeric grains or natural grains which are incompressible when subjected to filtration pressure, which have a sphericity coefficient in the range from about 0.6 to about 0.9, which have an average grain 5ize in the range from about 20 um m to about 70 um m, which are adapted to form a filter cake having a porosity in the range from about 0.4 to about 0.8 and a density in the range from about 1000kg/m<3> to about 1500 kg/m<3>,said filtration aid being adapted to be mixed with said liquid carrying impurities and to be deposited together and mixed with said liquid carrying impurities and to be deposited together and mixed with said impurities on a filtration medium of a filtration installation after filtering said liquid, wherein said method comprises, after one or more filtration steps, a step of regeneration in situ of said filtration aid by carrying out the method according to any one of claims 1 to 13.