Electrodialytic remediation of air pollution control residues

Air pollution control (APC) residue from municipal solid waste incineration (MSWI) consists of the fly ash, and, in dry and semi-dry systems, also the reaction products from the flue gas cleaning process. APC residue is considered a hazardous waste due to its high alkalinity, high content of salts, and content of mobile heavy metals. The volume of APC residue is presently increasing due to the increased focus on utilization of renewable energy sources, and thus occupation of new waste–to-energy plants. Various solutions for the handling of APC-residue exist in different regions, however, most commercial solutions are concerned with deposition; e.g. in abandoned mines. A demand for more environmentally friendly alternatives exists. Electrodialysis could be such an alternative, and the potential is being explored. Some main challenges are the extremely high soluble fraction together with the fact that many of the toxic elements are encapsulated in the particles rather than adsorbed to their surface.