The Feasible Study on the Reuse of Fly Ash Produced in the Sewage Sludge Incinerator Using Solidification/Stabilization Technique

摘要

The quantity of sewage sludge has been increased as the number of sewage treatment plants increased and a large portion of sludge has been treated as ocean disposal and incineration. Incineration and recycling processes could be expected widely to use where the ocean disposal would be prohibited. Many type of incineration process produces fly ash and/or bottom ash which contains very low organic compounds and very small particles. Cement-based solidification/stabilization is one of the preferred chemical treatment techniques for inorganic hazardous wastes, such as fly ash. In this study the reuse of fly ash produced from the sewage sludge incinerator was researched and evaluated using the solidification/stabilization technique. The experimental results showed that the unconfined compressive strength could be obtained over 500 kg/cm~2 in the condition of ambient temperature curing and the mixing ratio of fly ash 20%. Up to 65% of fly ash ratio the compressive strength could satisfy all Korean standards for the concrete brick (82 and 163 kg/cm~2), and within 50% over 300 kg/cm~2 could be maintained. The addition of fly ash could increase the compressive strength with the pozzolanic effect and also small particle could fill micro pores inside the specimens from the microstructure SEM analysis. This brick also satisfy the Korean standards for the absorption ratio. From the leaching test, the elution concentration of heavy metals was not detected or very low near detection limit It means that specimens stabilized could be very stable and safe in the environment. The experimental results showed that the fly ash from the sewage sludge could be widely reused and satisfy the unconfined compressive strength and leaching test.