PTFE membrane filter for exhaust air of vacuum toilet system

In a vacuum toilet system including a waste water tank, a toilet, a waste collection line connecting said toilet to said tank, a vacuum exhaust line, and a filter arrangement connected to said tank and interposed between said vacuum exhaust line and said tank,

• an improvement wherein said filter arrangement comprises:
• a filter housing arranged on said tank, wherein said housing comprises a housing wall bounding a flow channel, a vacuum exhaust outlet communicating from said flow channel to said vacuum exhaust line, and a drain opening communicating downwardly from said housing into said tank;
• and
• a filter element arranged in said filter housing, wherein said filter element has an outlet side surface and opposite thereto an inlet side surface, said outlet side surface bounds said flow channel with said flow channel between said housing wall and said filter element, said inlet side surface communicates with said drain opening, said filter element comprises a polytetrafluoroethylene (PTFE) filter membrane at said inlet side surface thereof, and said filter element is arranged so that contaminants filtered by said filter element out of a volume flow that flows through said filter element from said inlet side surface to said outlet side surface can run from said filter membrane through said drain opening into said tank.