Natural fishbone was found effective for heavy metal stabilization (particularly Pb) in municipal solid waste incineration (MSWI) fly ash in a previous study presented by the authors. Natural fishbone containing hydroxyapatite (HAP) could stabilize Pb and Zn under appropriate conditions; however, undesirable release of Cu and P occurred in the presence of non-HAP fraction. Therefore, ignition of fishbone for optimizing this technique was investigated. Based on thermogravimetry and differential thermal analysis, mass loss test, and X-ray diffractometry, it was found that ignition not only removed the non-HAP fraction, but also increased the crystallinity of HAP in fishbone as a function of temperature. Various ignition temperatures were carefully evaluated based on the performance of candidate fishbones in metal stabilization under designated conditions. Accordingly, fishbone ignited at 430 °C (IGN-430) was selected. Both natural and IGN-430 fishbones were involved in the stabilization of heavy metals in fly ash under various scenarios. IGN-430 provided more efficient metal stabilization than natural fishbone under the same conditions, because it supplied more fishbone HAP at the same dose. The non-HAP fraction in fishbone was the main source of released P in the leachate and presumably facilitated Cu and Zn release from fly ash. This facilitation hindered metal stabilization, the influence of which was greater at higher liquid condition. Consequently, IGN-430 fishbone is preferred to natural fishbone used for metal stabilization in fly ash, as it provided a more efficient metal stabilization without undesirable release of the other elements. A solid-like condition was even more beneficial for heavy metal stabilization in fly ash by fishbone HAP.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- General Environmental Science
- Strategy and Management
- Industrial and Manufacturing Engineering