Schwing Bioset, Inc. offers indirect-heated, thermal drying technology for producing Class A material from dewatered municipal wastewater treatment sludge. Based on the use of a fluidized bed dryer, the approach is to granulate and heat the biosolids within the dryer, and produce a dry, cool, dust free material as the end product. The media for providing the thermal energy can be by use of circulated thermal oil, steam or hot water. The energy for heating the media can be from combustion of natural gas, digester gas, or even waste heat sources. The use of a fluidized bed keeps the number of moving parts to an absolute minimum.
Features of the technology include:
• Flanged, welded construction with minimal sealing surfaces allowing for minimal odors and dust issues
• Use of recirculated inert gas in closed loop drying and cooling steps, results in very high energy efficiencies and low volume of offgas
• Low operating temperatures, inert drying gas, and other measures result in very high level of plant safety
• Dewatered cake is introduced directly into the dryer rather than backmixed, allowing for a much simpler, easier to automate process