Yukio Noma and Akiko Kida

Hiroshima Prefectural Health and Environment Center

+ Correspondence should be addressed to Yukio Noma:
(1-6-29 Minami-machi, Minami-ku, Hiroshima 734 Japan)

Abstract

The fact that more than 70% of municipal solid waste is being incinerated is creating various problems at landfill sites. One such problem is that of incrustation caused by a calcium coating on water treatment equipment, pumps, mixer blades, rotating plates and the collector sewer. Incinerator ash contains inorganic compounds including calcium and heavy metals, especially air pollution control residues from slaked lime containing many free alkaline calcium compounds, a major cause of calcium scale. In order to prevent the build-up of calcium scale, carbonation treatment of highly alkaline municipal incinerator fly ash was studied. Moisture content, temperature and reaction time were shown to have an effect on carbonation. Carbonation was checked by the X-ray diffraction method and its effectiveness for insolubilization of calcium was determined by leaching tests (solid liquid ratio = 1/10 or 1/200) and column elution tests. Test results indicated that carbonated incinerator fly ash did not produce calcium scale and carbonation treatment was effective for the insolubilization of alkaline calcium compounds.

Key words: carbonation, calcium scale, solid-liquid ratio, municipal solid waste incinerator fly ash, leaching test