Abstract: A membrane filter comprises one or several tubular flow channels (1) for liquid which is to be treated in the filter. The walls of the flow channels consist on the inner side of membranes, which are supported by a supporting structure. An outer casing (2) surrounds the flow channels and limits a collection space (5) for permeate between the casing and the flow channels. According to the invention the flow channels (1) and the said collection space (5) are connected to separate outer circuits, comprising pumps to bring the liquid which is to be filtered (retentate) as well as permeate to circulate concurrently pass the membrane filter. The collection space is filled by filling bodies, which constitute an essential mechanical hinder for the flow of circulating permeate. Means in the form of disks (8) provided with holes, which abut against the outer casing, are arranged at the inlet to the flow channels.

Abstract: A method for producing milk with a lowered bacterial content is provided. Raw milk is divided by centrifugal separation into one fraction consisting of cream and another fraction consisting of skim milk. The skim milk fraction is directed into a microfilter in which part of the fat globules, protein, and bacteria are separated off. From the microfilter there is obtained a permeate which consists of skim milk having a lowered fat, protein and bacterial content, and a retentate having an increased fat, protein and bacterial content. The retentate is subsequently sterilized.