Patent ID: 8133457

Claim:
A unit for preparing a sample for the microbiological analysis of a predetermined volume of liquid that may contain microorganisms, said unit comprising a filter module and a collection module for receiving liquid coming from said filter module, with said filter module comprising an inlet compartment for inletting said predetermined volume by an inlet opening of said filter module, said inlet compartment being adapted to contain the whole of said predetermined volume, as well as an evacuation compartment for evacuating said predetermined volume by an evacuation opening of said filter module to said collection module, said evacuation compartment being separated from said inlet compartment by a filter membrane, the filter and collection modules being rotatably mounted relative to each other, and having, relative to each other, a first relative predetermined position, in which said evacuation opening of said filter module is in register with a first opening of said collection module and a second relative predetermined position different from said first position, in which said evacuation opening of said filter module is in register with a second opening of said collection module characterized in that said inlet and evacuation compartments are on opposite sides from each other relative to said filter membrane with said inlet compartment being arranged such that, when said predetermined volume is in said inlet compartment the liquid is in contact with the filter membrane over at least the majority of its surface; wherein said filter module comprises a body within which is fixed said filter membrane as well as a separation membrane that is situated between said inlet opening and said filter membrane, said separation membrane having a pore diameter greater than the pore diameter of said filter membrane, and wherein said filter module comprises another opening formed in said body and giving access to a compartment of said body situated between said separation and filter membranes.