Modern Belt Drying of Sludge – Innovative Sludge and Energy Management
Heindl, A., Ostermann, S., Dürr, J., HUBER SE
(free)
Abstract
Belt Drying is an important step for further thermal processing of sewage sludge. It has the advantage of using exhaust energy at rather low temperature levels and from different sources, continuous drying to a defined final dry substance content and safe operation. Sludge has to be pre-processed either by extruding or by back mixing to create surfaces for sufficient heat and mass transfer and to promote even and effective drying. When sludge from external sources has to be dried a sludge management and an intelligent moisture control is essential for a successful belt drying process. Thus dryer capacity can be fully exploited in all operation conditions and undisturbed operation can be assured. The presentation is finished by a calculation of the specific energy demand of a waste water treatment plant with digester and belt drying, expressed in kWh / inhabitant and year.
Keywords: Belt drying of sewage sludge, sludge management, control of dry substance content, specific energy demand of a waste water treatment plant with anaerobic digestion and integrated belt drying
Advantages of Belt Drying In general belt drying of sewage sludge has the following advantages:
- Constant output dry substance content and even drying,
- Highly automated continuous process with easy operation,
- Possible use of cheap, low temperature (waste) energy in the temperature range of usually 70 – 150°C,
- Operating with different temperature levels from different sources possible,
- Low footprint for a given water evaporation,
- Safe operation due to limited temperature in dryer,
- Low wear,
- Low amount of maintenance and cleaning work,
- Low specific electric and thermal energy demand.
