【Paper】
Simultaneous Treatment of Heavy Metals and Salts in Fly Ash by Scrubbing Using Chelating Agent Solution
Tsutomu Imaoka*, Michihiro Yamaga**, Wataru Nishijima**, Mitsumasa Okada** and Yuzo Inoue***
* Department of Environment Information, Faculty of Environmental Studies, Hiroshima Institute of Technology
** Department of Materials Chemistry and Chemical Engineering, Hiroshima University
*** Waste Management Division, National Institute for Environmental Studies
† Correspondence should be addressed to Tsutomu Imaoka:
Department of Environment Information, Faculty of Environmental Studies,
Hiroshima Institute of Technology
（2-1-1 Miyake, Saeki-ku, Hiroshima-city, Hiroshima, 731-5193 Japan）


Abstract
The objective of this study is to evaluate the effectiveness of the scrubbing of municipal solid waste incinerator fly ash using the chelating agent to simultaneously perform both heavy metals insolubilization and salts elution ash. High amounts of Pb and Zn were eluted from the non-treated fly ash used in this study. Scrubbing of the fly ash using 10 times volume of a chelating agent solution with 10％ chelating agent for fly ash by weight resulted in 100％ and 90％ insolubilization of Pb and Zn, respectively. Na, K and Cl in the fly ash were leached into twice volume of the supernatant. However, these ions remained in the fly ash, because a large amount of the supernatant was retained in fly ash. Therefore, a large amount of the supernatant was required in order to achieve high removal efficiency of these salts. On the other hand, elution of Ca and SO4 depended on the volume of the chelating agent solution, because solubility of CaSO4 in water is very low. Scrubbing using the chelating agent solution also produced the benefit of waste reduction of the fly ash: 37％ of waste reduction was achieved.


Key words: fly ash, heavy metals, salts, chelating agent solution, waste reduction