Method for manufacturing filter having ceramic porous film as separating film

A method for manufacturing a filter utilizing a ceramic porous membrane as a separation film, comprising the steps of:

• providing a cylindrical porous substrate having a plurality of through-holes formed along a longitudinal direction thereof, said plurality of through-holes including at least a first through-hole positioned proximate the center of the cylindrical porous substrate and at least a second through-hole positioned proximate the outer circumferential surface of the cylindrical porus substrate;
• substituting air in fine pores of the cylindical porous substrate with a liquid;
• isolating an inner side of the plurality of through-holes in the cylindrical porous substrate on which a separation film is to be provided from the outer circumferential surface of the cylindrical porous substrate on which a separation film is not provided;
• continuously feeding the film deposition slurry into the plurality of through-holes to allow the slurry to contact an inner wall of said inner side of the plurality of through-holes;
• applying a differential filtration pressure between said inner side of the plurality of through-holes of the cylindrical porous substrate and said outer circumferential surface of the cylindrical porous substrate;
• and
• depositing the slurry on said inner side of the plurality of through-holes of the cylidrical porous substrate;
• wherein an organic polymer is added to the slurry in an amount sufficient to prevent a pressure differential in the slurry between positions adjacent the inner wall of said inner side of said first through-hole and the inner wall of said inner side of said second tbrough-hole, said organic polymer comprising at least one material selected from the group consisting of welan gum, agar, starch and gelatin.