A filter chamber is integrated into the dryer. In the filter room of the 3 chamber dryer, there are 190 fine filter cartridges with a surface of over 2648 ft3 (75m3). The filters are made from fine needle-felted fabric. They have a special coating, are anti-static and water and oil resistant. They have a dustproof anchor due to the stitched-in tension ring with dual beading. The filter cartridges house a stainless steel support cage, which guarantees the full filter surface even when operating at low pressure.
The filter cartridges are connected together in a pipe frame. Using several pneumatic cylinders, the frame, and the connected filter, is vibrated and cleaned of adherent filter cake at defined intervals. A screw feeder beneath the filter conveys the filter dust into the holding chamber and mixes it with the dried sewage sludge.
Exhaust fans can be found over the filter chamber. Pressure sensors are arranged in the drying chambers. The dryer is kept in a constant state of low pressure using the exhaust fans. If the fan output increases above a pre-set value, the vibrating procedure automatically begins and the filters are cleaned in the continual drying procedure. The filter medium has a density in order to keep the dust value of the exhaust gas below 1 mg. As a result, the dryer is 95% below the TA Luft (air) threshold.