Wastewater sludge is dried to minimize its mass and to save sludge hauling and disposal costs. Handling and storage of dried sludge is easy. The dried product can be used as fuel; its caloric value is similar to that of brown coal.
During thermal sludge drying almost all water is evaporated, including surface, capillary and cell water. Supply of heat is needed, preferably from combined power and heat generation systems. A great portion of the drying heat is recovered from the exhaust and re-circulated. Solids contents in the dried product of 90% DS and above can be achieved.
We supply three different kinds of HUBER Sludge Dryers:
- Medium-Temperature Belt Dryers wherein the sludge is convectively dried with hot air (80 – 130° Celsius). The dried product has a solid concentration ranging from 65% DS to over 90% DS. The sludge can be simultaneously disinfected.
- Solar-Regenerative Dryers utilize solar energy as well as low-temperature heat for sludge drying to a solids content of usually above 65% DS. We preferably use waste heat or heat from renewable sources. This type of dryer is particularly suited for small to medium-sized wastewater treatment plants.
- Contact dryers: The disc dryer is designed for the partial drying of dewatered sewage sludge to 40 – 45% DR and is heated with saturated steam (up to max. 10 bar). Our disc dryer is used in combination with fluidized bed incinerators for medium to large volumes of sewage sludge.