Understanding Direct Flow and Crossflow Microfiltration in Food and Beverage Industry Applications

Direct flow (sometimes called “dead end”) filtration is applied when all the fluid to be filtered is driven, typically in industrial applications due to a supply pressure, in a direction perpendicular to a filtering surface; few applications are done by gravity feed. Contaminants are captured within the filtration media or build up on the surface, causing the differential pressure across the filter to rise as it blocks over the duration of the filtration process. The filtrate exits the filter on the downstream side. Once a certain differential pressure has been reached, after which the fluid flow rate decreases and/or the filter reaches its terminal differential pressure, filtration is stopped and the filter is either discarded or may sometimes be regenerated for re-use (Figures 1a–1b).