Andritz – Belt Drying System – provides highly desired Class A Biosolids in a highly marketable sludge pellet / granual. The process granulates the dewatered sludge in a mixer with product that has already been dried. The moist granulate produced here is distributed evenly over the belt in the dryer by a specially designed feed module. The even layer of material on the belt creates optimum conditions for even distribution of the drying air. This, in turn, is necessary for even heating and drying of the sewage sludge. The layer of material on the belt forms a
filter medium for the air flowing onto the granulate layer from above and thus prevents entrainment of dust. The low temperature of the drying gases (< 150°C) and the low dust content in the system facilitate safe operation. The dried material is not exposed to mechanical stress during drying and is pre-cooled before the dryer discharge. The technology – simple, convincing, and successful.
The belt dryer is particularly attractive economically because it uses waste heat with a low temperature.