42. Sludge Drying by Belt, Disk, and Rotary Kiln Dryers

Sludge is produced as a residue of the treatment of industrial and municipal wastewater and includes mostly water and insoluble and semisolid materials. The amount of the sewage sludge has become problematic together with the increasing population in cities and production of more wastewater. Sludge treatment systems have been developed to cope with the increasing amount of sewage sludge. Commonly used sludge treatment systems are sludge thickening, dewatering, drying, and incineration. The main goal of the sludge treatment is to remove the moisture content of the sludge by reducing the volume and weight. Water present in the sludge is also removed by thickening and dewatering process, but the highest volume reduction occurs in sludge drying process.

There are many different types of sludge drying method according to the energy sources and applications. The selection of the suitable sludge drying technology according to the plant requirement is of great importance. Sludge characteristics, energy requirement, final use of the dried sludge, and area requirements can be effective on the process selection.