HUBER installs its first combined solar and regenerative sewage sludge drying project

KULT® Solar Active Dryer SRT in Hayingen

The Hayingen wastewater treatment plant is situated in the idyllic valley of the river Lauter, situated on the long hiking trail from the Black Forest into the Allgaeu. The wastewater treatment facility blends perfectly into the local landscape.

Whilst it is accepted that the need for large surface areas is required for a pure solar drying plant, the local topography made it necessary to position the plant on the plateau next to the wastewater treatment plant. The new dewatering unit was installed to dewater the sewage sludge to 440 t/a with approx. 22 % DR. This resultant sludge would then be transported to the new drying plant via the municipality's road network.

The HUBER SRT sewage sludge drying system with combined solar and regenerative drying provides for sewage sludge dewatering and drying in one place. Only solar radiation available at site is used for drying. The additional regenerative component consisting of a heat pump assists the replacement of solar drying at times of little or no solar radiation. For this purpose the pump uses the heat of the wastewater treatment plant effluent and delivers it into the dryer.

The HUBER drying plant consists of a purpose built structure containing the dewatering unit, separate electric measuring and automatic control devices for the complete plant, and the subsequent dryer. The dryer cover is of a double plate construction used within the greenhouse industry. Inside the dryer the sludge is placed onto the perforated bottom, transported and mixed by a turning device. The air that has been heated by the heat pump then flows through the sludge layer. The dried sewage sludges automatically leaves the plant and is transported into a granulate collecting tank. With the integral design, manual feeding with sewage sludge or dryer evacuation by means of a wheel loader is unnecessary, which results in a safer working environment for the operating staff.

The plant is at present in the test run phase and achieving the required drying result of 90 % DR. Further adjustment and optimisation of the process will be tailored to suit the local conditions and plant requirements.