Abstract: There is disclosed a micro- or ultrafiltration process using a membrane module consisting of hollow fiber, tubular, or capillary membranes, comprising feeding the liquid to be treated in the space between the membranes; withdrawing the permeate, a product stream which is obtained by passing the liquid under the action of pressure gradient through the pores of said membranes from the outsides thereof to the insides thereof to trap the colloidally suspended particles on the outer surfaces and/or inside the pores of said membranes, from the inside of said membranes; withdrawing the filtrate, a product stream which is obtained by collection of said particles on the outside surface of said membranes due to adsorption and/or other particle collection mechanisms, under the action of pressure difference across a control valve, or any other flow control device, at the filter outlet.