Patent ID: 8110112

Claim:
A method for concentration of biological particulates in a liquid comprising: flowing a first volume of process feed material that bears particulates entrained in a fluid through a hollow fiber filter to separate an amount of the particulates from the fluid by trapping the amount of particulates on a feed side of the hollow fiber filter; providing a wash liquid and a water soluble gas under pressure, the wash liquid becoming a foam liquid wash material as the gas is released from under pressure and agitated; and extracting the amount of particulates from the feed side of the hollow fiber filter by flowing the foamed liquid wash material through a fluid path extending from a permeate side of the hollow fiber filter across the hollow fiber filter to the feed side of the hollow fiber filter, the foamed liquid wash material biologically and analytically compatible with the particulates, by opening a valve that is controlled with a timer to dispense reproducible volumes of foam by controlling foam pressure and valve opening time, such that this step of extracting provides a second volume of concentrated particulates in the wash liquid.