School Civil and Environmental Engineering, Nanyang Technological University, Singapore.
School Civil and Environmental Engineering, Nanyang Technological University, Singapore.
Waste Manag. 2021 Feb 1;120:183-192. doi: 10.1016/j.wasman.2020.11.030. Epub 2020 Dec 10.
This study systematically investigated the acid washing of incineration bottom ash (IBA) of municipal solid waste, focusing on the removal and leaching of heavy metals (Pb, Zn, Cr, Cd, Cu, and Ni), as well as their pH-dependent behavior. A series of small-scale laboratory acid washing tests with different nitric acid concentrations and washing periods were conducted. The concentrations of metals in the washing water were measured to evaluate the metal removal efficiency. Then, one stage batch leaching test was conducted for washed IBA to evaluate the leaching reduction efficiency of washing. The results showed that the maximum metal removal efficiencies for Zn, Cu, and Ni (62-76%) were higher than those for Pb, Cr, and Cd (17-25%), which were reached at the highest acid addition for most of the metals. Increasing the washing period did not always increase the metal removal efficiency. The maximum leaching reduction efficiencies were higher for Zn, Cr, and Cu (93-98%) than those for Pb, Ni, and Cd (73-79%). Both washing and leaching processes showed a similar metal concentration-pH profile for each metal. For Pb, Zn, Cr, and Cd, the metal concentration-pH profile generally followed the metal hydroxide solubility versus pH curves. For Cu and Ni, the concentration of metal decreased with the increasing pH first and then kept at a stable concentration higher than the solubility of the hydroxide, indicating that Cu and Ni in the IBA washing water and leachates did not exist dominantly as their hydroxides.
本研究系统地考察了城市固体废物焚烧底灰（IBA）的酸浸过程，重点研究了重金属（Pb、Zn、Cr、Cd、Cu 和 Ni）的去除和浸出及其 pH 值依赖性行为。进行了一系列不同硝酸浓度和洗涤时间的小规模实验室酸浸试验。测量洗涤水中金属的浓度以评估金属去除效率。然后，对洗涤后的 IBA 进行了一个阶段的批量浸出试验，以评估洗涤对浸出的减少效率。结果表明，Zn、Cu 和 Ni（62-76%）的最大金属去除效率高于 Pb、Cr 和 Cd（17-25%），大多数金属在最高加酸量时达到最高去除效率。增加洗涤时间并不总是会提高金属去除效率。Zn、Cr 和 Cu（93-98%）的最大浸出减少效率高于 Pb、Ni 和 Cd（73-79%）。洗涤和浸出过程都显示出每种金属相似的金属浓度-pH 分布。对于 Pb、Zn、Cr 和 Cd，金属浓度-pH 分布通常遵循金属氢氧化物溶解度与 pH 值曲线。对于 Cu 和 Ni，金属浓度先随 pH 值增加而降低，然后保持在高于氢氧化物溶解度的稳定浓度，这表明 IBA 洗涤水和浸出液中的 Cu 和 Ni 并不主要以其氢氧化物的形式存在。
