Blood circulates through your kidneys every 40 minutes. Each day, your kidneys cleanse 180 liters of blood. The kidneys release the wastes as urine. Water and nitrogen products can collect in the blood of damaged or diseased kidneys. This causes life-threatening conditions. A kidney machine eliminates wastes by artificially filtering the blood. In this process, called hemodialysis, blood circulates through a machine functioning as the patient’s kidney. The treatment applies the process of diffusion, which occurs when molecules move from higher to lower concentration. This occurs because the concentration of waste in the cleansing solution is lower than that of the blood. Cleansed blood is returned to the patient.