福州地区垃圾焚烧飞灰中矿物组分和重金属污染特征

MINERAL COMPONENTS AND HEAVY METAL POLLUTION CHARACTERISTICS IN WASTE INCINERATION FLY ASH IN FUZHOU

采集福州某焚烧发电厂飞灰,分析和对比不同地区矿物组分和重金属污染特征。结果表明:此飞灰主要矿物组分除CaCO和SiO外,还包含可溶性氯盐(NaCl、KCl)和不可溶氯盐(AlOCl)。重金属总量顺序为Zn>Pb>Cu>Cd>Cr>Ni。与全国不同地区的飞灰一致,Zn和Pb总量均较高;Pb超出GB 16889—2008《生活垃圾填埋场污染物控制标准》的浸出毒性标准限值。形态分析结果表明,Cd(83.3%)和Cu(66.2%)的不稳定态占比高,Zn(47.0%)和Pb(36.6%)的不稳定态也具有一定占比。相比于短期浸出和浸提剂种类(纯水、醋酸和盐酸),5 mol/L盐酸长时间重金属浸出效果显著,Zn和Pb浸出浓度明显增强,且Zn最大;受形态和总量影响,Cu、Cd、Cr和Ni浸出浓度相对较低。因此,飞灰长期堆积在环境中仍具有较高的潜在风险。不同区域飞灰的矿物相及其重金属污染特征存在一定普遍规律,并具有地域特征。该研究成果可为后期飞灰固定稳定化方法提供数据支撑。

This study collected fly ash from an incineration power plant in Fuzhou, analyzed and compared the mineral components and heavy metal pollution characteristics in different areas in China. The results showed that the main mineral included the soluble chloride salts(NaCl, KCl) and insoluble chloride salts(AlOCl), apart from CaCOand SiO. The order of heavy metal total amount was Zn>Pb>Cu>Cd>Cr>Ni, and the total amount of Zn and Pb was higher, the same as that in some other areas in China;the leaching concentration of Pb exceeded the standard limit, GB 16889—2008 in the leaching toxicity test. The morphological analysis also showed that the unstable state of Cd(83.3%) and Cu(66.2%) accounted for high proportions, and that of Pb(36.6%) and Zn(47.0%) also accounted for certain proportions. Compared with the short-term leaching and the types of extractants(UPW, acetic acid and HCl), 5 mol/L HCl had a significant leaching effect under the long-term leaching condition, and the leaching concentrations of Zn and Pb significantly rose, and Zn leaching concentration was the highest in all heavy metal elements;the leaching concentrations of Cu, Cd, Cr, and Ni were relatively lower under the influence of total amount and speciation of heavy metal. Therefore, long-term storage of fly ash in the environment still possessed a high potential risk. The mineral components and heavy metal pollution characteristics of fly ash in different areas have certain universal laws and regional characteristics, which can provide data support for the development of fly ash immobilization and stabilization methods.