12 - Incinerated sewage sludge ash blended cementitious materials

Abstract

Incinerated sewage sludge ash (ISSA) as solid waste material is produced worldwide where incineration is used to manage sewage sludge, and improper disposal of ISSA has become an environmental concern. This chapter therefore provides a summary of the physical and chemical properties of ISSA and the effect of using ISSA in various cementitious materials, such as sintered material, cement additives, and precursors. The appropriate use of the ISSA can improve the fresh and hardened properties of cement-related materials. Beyond that, air pollution control (APC) residues from the sewage sludge incineration process were considered hazardous waste that required some specific treatment before disposal. Especially, the novel use of the sulfate from the APC residues as activators for silica-aluminum precursors for alkali/sulfate-activated cement was reviewed. These multiple applications of ISSA and APC residues in various cementitious materials are considered important steps toward waste recycling as a sustainable material. Lastly, the leachability risk of the ISSA and APC residues is highlighted to alleviate public apprehension regarding sewage sludge incineration technology. Meanwhile, the immobilization mechanisms of potentially toxic elements were elaborated to facilitate the design of cementitious materials and the actualization of sustainable management for ISSA and APC residues.