Abstract:

Aiming at the problem of heavy metals leaching in the application of municipal solid waste incineration bottom ash resources, a continuous column leaching test device was constructed to simulate natural rainfall. The dynamic leaching analysis of 0—5mm and 5—10mm MSW incineration bottom ash was carried out. Attention was paid to the leaching of heavy metals Cu²⁺ and Zn²⁺ under different acid rain conditions and rainfall intensity. The results show that the pH value of the leachate has a great effect on the leaching levels of Cu²⁺ and Zn²⁺ during dynamic leaching. The level of Cu²⁺ leaching is stronger than that of Zn²⁺ in a strongly acidic leachate environment. Compared with the concentration limit of surface water environment in the Class Ⅴ, the concentration of Cu²⁺ leaching seriously exceeds the standard during the entire leaching time, relevant environmental risks need to be prevented in the application of slag engineering. The size of bottom ash has no direct correlation with the leaching level of heavy metals, but the content of leaching Zn²⁺ in the primary bottom ash with a small diameter of 0—5mm is higher, which is related to the occurrence form and the higher soluble Zn in the fine particles. The effect of leaching strength on the leaching level of heavy metals mainly reflects the liquid-solid ratio and water migration rate during the dynamic leaching process. When the leaching strength is lower, the liquid-solid ratio is lower and the heavy metal content in the eluate is higher.

Key words: MSW incineration bottom ash, column leaching, heavy metals, leaching concentration

摘要：

垃圾焚烧炉渣是一种活性材料，在其储存、预处理及应用等过程与雨水频繁接触时，炉渣中重金属随着水域环境发生迁移和浸出现象。本研究采用连续柱淋滤试验装置模拟自然降雨，开展了0～5mm和5～10mm焚烧炉渣的动态淋滤毒性浸出分析，重点研究了pH和降雨强度对Cu²⁺和Zn²⁺的浸出影响。结果表明，动态淋滤过程中，淋滤液pH变化对Cu²⁺和Zn²⁺的浸出水平影响显著，且在酸性较强淋滤液作用下Cu²⁺浸出水平比Zn²⁺更强，与Ⅴ类地表水环境浓度限值对比，在整个淋滤时间内Cu²⁺浸出浓度严重超标，在炉渣工程应用时需预防相关的环境风险；原生炉渣粒径大小与重金属浸出水平无直接相关性，但是0～5mm细炉渣中可浸出Zn²⁺含量更高，这与细颗粒物中Zn赋存形态和可溶出态含量较高有关；淋滤强度对重金属浸出水平影响主要反应了动态淋滤过程液固比和水分运移速率情况，当较低淋滤强度时具有低液固比，溶出液中重金属含量较高。

关键词: 生活垃圾焚烧炉渣, 柱淋滤, 重金属, 浸出浓度