The present invention relates to modification to permeate channels and permeate materials in a cross-flow filtration system to improve performance in counter current filtration having both retentate channels and permeate channels wherein a solution is pumped through one of the channels and drawn through a membrane to one of the other channels to assist in positive pressure driven filtration by using the osmotic pressure, concentration, or preferential solubility difference between the retentate and permeate flow streams thereby increasing or altering the flux through the membrane separating the flow streams.