Filter system for a printing machine

A filter system for a printing machine through which process water is circulated, the system comprising:

• a filter basin having an inlet and an outlet below the inlet;
• a supply line between the printing machine and the inlet for conducting the process water from the printing machine to the inlet;
• a return line between the printing machine and the outlet for returning the process water from the basin to the printing machine;
• a closed water-permeable conveyor belt having an upwardly concave upper stretch extending through the basin between the inlet and the outlet and displaceable in a travel direction through the basin, whereby the upper stretch defines in the basin an upper inlet zone including the inlet and a lower outlet zone including the outlet;
• a supply of an elongated fleece filter web;
• guides for feeding the filter web onto an upstream end of the upper stretch of the belt and off a downstream end of the upper stretch of the belt such that the filter web lies atop the upper stretch and hydrostatic pressure of the process water in the inlet zone presses the web down onto the upper stretch;
• and
• drive means for advancing the upper stretch of the belt and the web lying thereon in the travel direction such that the web advances through the basin.