焚烧飞灰重金属含量及浸出长期变化规律研究

通过对24个飞灰样品的重金属全量消解和高精度X射线荧光光谱法（HDXRF）快速检测结果进行线性回归分析，发现HDXRF法可较准确测定飞灰中Cu、Pb、Zn、Ni和Cd含量（线性回归决定系数R²³0.90）.采用HDXRF法对某焚烧厂飞灰重金属含量6个月快速检测及浸出毒性测定数据统计分析发现：飞灰重金属月均含量较稳定（变异系数CV<0.14）但日均含量波动较大（CV>2.54）；飞灰中Pb、Cu和Zn含量呈正相关（相关系数r>0.78）；金属浸出浓度受浸出液终点pH值影响显著，超标频率依次为Pb（68.9%）、Cd（66.1%）、Ni（24.0%）、Cu（14.2%）和Zn（1.6%）.短期飞灰金属含量和浸出毒性数据受焚烧工况，烟气处理工况和垃圾组分等多种因素共同影响，不具有代表性.为评估垃圾分类源头削减重金属效果，建议采用快速检测方法对焚烧飞灰重金属含量进行长期监测.

Study on the long-term changes of heavy metal content and leaching behavior of municipal solid waste incineration fly ash

Both acid digestion and high definition X-ray fluorescence spectrometry (HDXRF) methods were used to measure the contents of Cu, Pb, Zn, Ni and Cd for 24fly ash samples. The good correlation(coefficient of determination R²≥0.90) determined by linear regression analysis between the results from these two methods demonstrated that HDXRF was an accurate and rapid technique for the determination of heavy metal content. Then, HDXRF was used to evaluate fly ash samples collected from a typical grate incinerator for six months. The results showed thatthe monthly average contents of heavy metals remained consistent with coefficient of variation (CV) less than 0.14, whiletheir daily average contents fluctuated significantlywithCV over 2.54; changes in contents of Pb, Cu and Zn were positively correlated; andthe metal leaching concentration was significantly affected by the pH of the end point of the leaching solution, Pb and Cd were the elements that exceed the stipulated limit (GB 16889-2008) most, followed by Ni, Cu and Zn.The short-term variations of metal contents and leaching toxicity were affected by many factors, including the conditions of incineration, purification technologies of flue gas, and compositions of wastes, et al. To assess the effectiveness of garbage sorting in reducing heavy metals at source, a rapid detection method (e.g., HDXRF) could be adopted to monitor heavy metal contents of fly ash for a long period.