A device for thermally treating products in containers, including supply and discharge conveyors for containers with at least one irrigation or spraying zone for irrigating or spraying the containers with a process liquid, for example water and a circulation circuit for at least partially reusing said process liquid, the circulation circuit including at least one pump with at least one separation unit with several essentially parallel lamellae for cleaning the process liquid from particles, for example broken glass and/or sand, and the pump pumps the process liquid along the lamella.
