Dose-mortality assessment on municipal solid waste incinerator (MSWI) ash

This study provides a novel attempt to put forward, in general toxicological terms, quantitative series of toxicity of various ashes of municipal solid waste incinerator (MSWI) for reusability in various applications. Previous study disclosed that growth inhibition of Escherichia coli DH5alpha occurred at concentrations above 0.156, 0.625 and 0.0195 gL(-1) for bottom ash (BA), cyclone ash (CA), scrubber ash (SA), respectively, suggesting the toxicity series of SA>BA>CA. However, the severity of such a toxicity series was not clearly revealed, thus whether ashes were still feasible for reuse in further applications was still remained uncertain. Compared to NaNO3, CrCl2 and CdCl2, the existing toxicities of ashes were apparently significant even these ashes were all satisfied by the TCLP guidelines for EPA regulations. Dose-response analysis based upon loss of cell viability (e.g., EC50) stated a toxicity series of SA>CrCl2>BA>CdCl2>CA>NaNO3. The ranking of Hill slope B in BA>SA>CA>NaNO3>CrCl2>CdCl2 clearly suggested the smallest tolerance (e.g., ranges from EC20 to EC50) for ashes very likely due to synergistic toxicity of multiple species present in ashes. The findings showed that toxicity attenuation of ashes should be the first-ranking task prior to practical reuse and recycle in applications.