Abstract: A hemodialysis apparatus separates constituents from blood plasma utilizing layered gel membranes of differing permeabilities configured as a U-tube. Physical filter pressing of blood plasma is accomplished by pinching gel beds along the U-tube axis where localized pressure rise and centrifugal forces are established. The U-tube fold also establishes chemical countercurrent pumping across the gel beds. Capillary and electroosmotic gel filtration further accomplishes selective chemical removal and readsorption.