Method for removing fluid from a blood filter at the end of a blood treatment session and treatment apparatus for executing the method

A system for displacing dialysate fluid from a dialysate chamber of a blood filter used for a blood treatment of a patient, said system comprising:

• a control or regulating device configured to control or regulate the execution of a method comprising:
• after the blood treatment of the patient and prior to emptying a blood chamber of the blood filter such that the blood chamber contains full of blood, closing or sealing the blood chamber against atmosphere, wherein the blood filter includes a membrane arranged between the blood chamber and the dialysate chamber, wherein the blood chamber is connected with an arterial blood line leading to the blood chamber and with a venous blood line leading away from the blood chamber, and wherein the dialysate chamber is connected with a dialysate inlet line leading to the dialysate chamber and with a dialysate outlet line leading away from the dialysate chamber;
• and
• while the blood chamber remains closed or sealed against the atmosphere and prevented from emptying, displacing the dialysate fluid from the dialysate chamber by actively or passively introducing air or a liquid into the dialysate inlet line such that the air or liquid enters the dialysate chamber, wherein no fluid from the dialysate chamber transfers across the membrane during the displacing.