Belt Drying of Sludge

This professional book deals with belt drying of sewage sludge, mainly of municipal but also of industrial origin. The wastewater treatment resulting in sludge production is briefly described. The types of sludge and their degree of stabilization is treated in depth as they have a high impact on their suitability for belt drying and the necessary exhaust air treatment. Different belt drying systems with or without condensing units and with extruding of dewatered sludge or partial recirculation of dried sludge are presented. Specific water evaporation and energy demand are tabulated for each dryer system on basis of indications of dryer manufacturers, measurements or information of dryer operators. Different sources for thermal energy are stipulated and complete systems of energy supply with internal or external usage of exhaust energy described. Occurring gas compounds in dryer exhaust air and their special features are mentioned in depth. The components and complete systems for exhaust air cleaning are discussed also in their efficiency of removal of individual odorous gas components or of total amount of volatile organic compounds. Conveying systems and storage of dewatered sludge as well as of dried sludge are described together with the related safety issues. Dryer control as well as ATEX, SIL and HAZOP issues and economic aspects are discussed briefly in individual chapters.