Solar sludge drying

The solar dryer consists of two lightweight halls equipped with a mechanism for loosening, turning, and moving sludge during drying. The halls are designed as ventilated greenhouses heated by solar energy. Saturated vapors are removed by longitudinal ventilation flaps installed in the ridge of the hall, while fresh air is drawn in through double-sided longitudinal slits along the length of the hall. The hall is covered with a special double-layer blown film. Solar energy (greenhouse effect) is mainly used for drying. In the event of excess heat from sludge management operations, a heating system using hot water units (4 per hall) with a total maximum output of 220 kW can be used to intensify drying. The system includes an intermediate storage facility for dewatered sludge, which serves as an operational depot for imported sludge or sludge from dewatering. Dewatered sludge is transported to the solar halls by a wheel loader. In the future, the dried sludge will be used as a renewable energy source.

The contract was awarded in the form of Design&Build.

The basic parameters of the construction are:

• Dimensions of the solar hall (2 in total)
• Floor plan dimensions of usable area 125 x 12 m
• Usable area of the hall (drying area) 2 x 1,500 m²
• Dewatered sludge fed into the halls 3,465 t/year
• Average initial dry matter content 20.6%
• Amount of dried sludge 1,189.7 t/year
• Amount of water evaporated by solar energy 2,275.4 t/year
• Estimated average evaporation in the location 817 kg/m²/year
• Dry matter in dried sludge (annual average) 60%