After the biosolids are partially dewatered at the belt filter press they are trucked to the solar dryers for final processing. The solar drying building is a green house structure with computer controlled fans, ventilation, and tilling equipment. Instruments measure both the inside and outside climate for temperature, humidity, wind speed, and solar radiation. Using information from these sensors the computer controls the ventilation doors and ceiling fans to create optimum drying conditions.

Four large fans on one end of the solar dryer work independently to control the inside humidity by exhausting moisture laden air.

Dewatered biosolids are almost completely dry. The mole is an electric tiller also controlled by the computer. It tills the solids to aid drying. Ceiling fans are automatically controlled to blow the hotter air at the ceiling onto the solids.

"Herkules" the electric mole tills the wet biosolids. Using a series of ultrasonic sensors, Herkules can navigate the interior of the solar dryer. It can run forwards and backwards or turn avoiding walls or any other obstruction that would cause it to get stuck.

Herkules shows off the control center for its motors and sensors.

Old versus new. The old sludge drying beds are in the foreground, behind are the new solar dryers that have made the beds obsolete.

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