Department of Civil and Environmental Engineering, Jackson State University, Jackson, MS 39217, United States.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085, China.
J Environ Sci (China). 2021 Mar;101:282-292. doi: 10.1016/j.jes.2020.08.023. Epub 2020 Sep 9.
Steel slag (SS) is one of byproduct of steel manufacture industry. The environmental concerns of SS may limit their re-use in different applications. The goal of this study was to investigate the leaching behavior of metals from SS before and after treated by microbially induced carbonate precipitation (MICP). Toxicity characteristic leaching procedure, synthetic precipitation leaching procedure and water leaching tests were performed to evaluate the leaching behavior of major elements (Fe, Mg and Ca) and trace elements (Ba, Cu and Mn) in three scenarios. The concentrations of leaching metals increased with the content of SS. After it reached the peak concentration, the leaching concentration decreased with the content of SS. The leachability of all elements concerned in this study was below 0.5%. The carbonate generated from the MICP process contributed to the low leachability of metals. After bio-modified by MICP process, the leaching concentrations of Ba from TCLP, SPLP and WLT tests were below 2.0 mg/L, which was the limit in drinking water regulated by U.S. EPA. The concentrations of Cu leached out from MICP-treated SS-sand samples were below 1.3 mg/L which is the limit regulated by national secondary drinking water. Compared with the regulations of U.S.EPA and Mississippi Department of Environment Quality (MDEQ), MICP-treated samples were classified as non-hazardous materials with respects to the leaching of metals. Meanwhile, maximum contaminant limits regulated by U.S.EPA states that MICP-treated SS are eco-friendly materials that can be reused as construction materials.
钢渣（SS）是钢铁制造工业的副产品之一。SS 的环境问题可能会限制其在不同应用中的再利用。本研究的目的是研究微生物诱导碳酸沉淀（MICP）处理前后 SS 中金属的浸出行为。采用毒性特征浸出程序、合成沉淀浸出程序和水浸出试验，评估了三种情况下主要元素（Fe、Mg 和 Ca）和微量元素（Ba、Cu 和 Mn）的浸出行为。浸出金属的浓度随 SS 含量的增加而增加。达到峰值浓度后，浸出浓度随 SS 含量的增加而降低。本研究中所有关注元素的浸出率均低于 0.5%。MICP 过程中生成的碳酸盐有助于降低金属的浸出率。经过 MICP 生物改性后，TCLP、SPLP 和 WLT 试验中 Ba 的浸出浓度均低于 2.0mg/L，低于美国环保署规定的饮用水限值。MICP 处理后的 SS-砂样中 Cu 的浸出浓度低于 1.3mg/L，低于国家二级饮用水规定的限值。与美国环保署和密西西比州环境质量部（MDEQ）的规定相比，MICP 处理后的样品在金属浸出方面被归类为非危险材料。同时，美国环保署规定的最大污染物限值表明，MICP 处理后的 SS 是可重复用作建筑材料的环保材料。
