Sludge-based ceramsite for environmental remediation and architecture ingredients

Environment-friendly and cost-effective disposal and reutilization of sludge wastes are essential during the wastewater treatment process. Converting sludge wastes into ceramsite by sintering treatment is a promising strategy for sludge treatment. This paper summarizes existing processes and technologies for regenerating ceramsite from sludge wastes. The synthesis process including raw material pretreatment, sludge characteristics analysis, batching, mixing and molding, drying and preheating, sintering and cooling is discussed. Then, the effects of additives, sintering temperature and time, and sludge content on the preparation and properties of sludge-based ceramsite are summarized. Integrating mechanistic insights and different physicochemical properties highlighted the understanding of the different applications (environmental remediation and architecture ingredients) of sludge-based ceramsite. High-temperature sintering sludge-based ceramsite exhibited excellent performance for the removal of contaminants due to the high porosity, large surface area, and good biocompatibility. Besides, the sludge-based ceramsite could also be used as concrete aggregate and asphalt mixtures due to its high strength, thermal insulation, and seismic resistance. Finally, the challenges and proposals for sludge-based ceramsite are proposed. This paper can provide a theoretical basis and guidance for the preparation and application of sludge-based ceramsite.