A filter that functions as an artificial kidney and typically used in a haemodialysis system to remove impurities from the blood of a patient suffering from sudden failure or chronic malfunction of the kidneys. The device typically consists of sheets of a semi-permeable membrane that are placed as disposable (single-use) inserts between permanent (reusable) support plates to form parallel layers; the blood and dialysate circulate in separate alternating compartments. The impurities and fluids in the blood are moved across the membranes to the dialysate under a pressure gradient (diffusion and ultrafiltration) for removal.