Cross-flow filtration applies tangential flow over the membrane, where the actual system pressure forces filtrate (permeate) through the membrane. The cross-flow/tangential flow greatly reduces the build-up of material/solids on the membrane surface (“self-cleaning” effect) allowing relatively long operating time between cleanings, when designed correctly.
Conventional filtration or “Dead-End” filtration, e.g. bag filters, use designs where flow and pressure are directed “perpendicularly” on the filter/membrane. Material/solids will relatively fast build up on the filter/membrane surface, and gradually reduce the flow and eventually block the surface. The filter either needs emptying or replacement (depending on design) before the filtration can continue.