Value Addition of Wastewater Sludge: Future Course in Sludge Reutilization

Abstract

Sludges are inevitable products of wastewater treatment processes, which have to be managed efficiently to meet stringent laws and regulations being enforced day by day. Currently, there exist three major options for complete sludge management—control at source by process modification; improvement in handling, processing, and disposal, and reuse to produce value-added products. The source control and improvement in handling and disposal practices have been reviewed by various authors and it is actually sludge reprocessing to value-added products that holds the future key to sustainable management. Thus, the primary focus of this review is the value addition of sludge comprising recovery of different components and development of commercial products. The production of various value-added products, namely, soil amendments, construction aggregates, fuels, biotechnology products, biosorbents, and miscellaneous have been examined addressing the key issues of production method limitations, benefits, and possible field application.