Physicochemical aspects of sludge drying

Untreated municipal sludge could be regarded as hazardous waste material due to its high organic and metallic content. Decreasing sludge moisture content is the primary objective for all sustainable sludge management strategies. Although a signicant amount of free water in sludge is removed by mechanical dewatering processes, the moisture content of sludge is still higher than 70% (dry basis). According to the current regulations, the percent solids of sewage sludge shall be equal to or greater than 90%, based on the moisture content and total solids prior to storage for all kinds of land applications. In addition, high moisture content would make sludge conveying, pumping, and transportation extremely difcult. Composition of the sludge depends on wastewater characteristics and the treatment technology employed [1]. © 2015 by Taylor & Francis Group, LLC