96/04066 Municipal solid waste — incineration, air pollution control and ash management

Abstract

Recycling valuable elements from municipal solid waste incineration fly ash and air pollution control (APC) residue has become the focus of research to manage this kind of residual waste. This paper assesses the possibility of energy savings to increase the economic sustainability of the electrodialytic (ED) recovery process by using pulsed stirring during extraction of As, Cd, Cr, Cu, Pb, and Zn from fly ash and APC residue suspensions and analyzing the data with multivariate statistical methods. Fly ash and APC residue in different batches were ED treated using different stirring frequencies of the ash suspensions, i.e., manually, 25%, 50%, 75%, and 100% (constant) stirring. An automatic camera was used to record the effect of pulsed stirring on the distribution of the ash suspensions during ED treatment and revealed three stages of the ash suspension during ED treatment that was presented in a conceptual model. The results showed that applying both pulsed and constant stirring could increase the acidification, the redox potential of ash suspensions, and the contact between ash particles and H+, thus boosting the extraction of metals. The regression coefficients and variable influence on projection values based on partial least squares models show similarity between 50% stirring and 100% stirring, indicating that it is possible to save energy by applying the stirrer only 50% of the time for all ashes, without compromising the extraction of the metals.