Abstract: 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.