School of Civil Engineering, Architecture and Environment, Hubei University of Technology, 430068, China; School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore; Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Hubei University of Technology, 430068, China.
School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore; Nanyang Environment & Water Research Institute, Nanyang Technological University, 639798, Singapore.
Chemosphere. 2022 Sep;303(Pt 1):135011. doi: 10.1016/j.chemosphere.2022.135011. Epub 2022 May 21.
Each year, extensive dredged clay slurries containing heavy metals need to be treated before being reused; in such contaminated slurries, lead (Pb) is frequently identified. Quicklime (CaO)-activated ground granulated blast-furnace slag (GGBS), magnesium (MgO)-activated GGBS, and ordinary Portland cement (OPC) are usually used to remediate the lead (Pb)-contaminated soil; nevertheless, using these curing agents (or binders), particularly CaO-GGBS and MgO-GGBS, to treat Pb-contaminated slurry with high water content is rarely reported. Moreover, inconsistent results were obtained from previous studies in terms of the mechanical and leaching performance of Pb-contaminated soils with the three binders. Based on the above-mentioned reasons, this study used CaO-GGBS, MgO-GGBS, and OPC to treat the Pb-contaminated clay slurry, and compared the effectiveness of the three binders in improving the mechanical and leaching properties of the slurry. Laboratory tests were performed to examine the leaching, strength, mineralogical, and micro-structural performance of treated clay slurries. The results showed that GGBS-based binders were more effective than OPC in improving the strength and Pb leachability of contaminated slurries. When suitable ratios between activators (CaO and MgO) and GGBS were used, a similar or even higher UCS was produced by CaO-GGBS than MgO-GGBS. Similar leachate pH and Pb leachability could be achieved between CaO-GGBS- and MgO-GGBS-treated contaminated clay slurries. Therefore, it is not rigorous to state that MgO-GGBS is better in improving the strength and leachability of Pb-contaminated soils than CaO-GGBS only by comparing the two GGBS-binders based on the same activator/GGBS ratio, as reported in some previous studies. The leachability of Pb was affected by the pH, but the addition of GGBS facilitated the decrease of Pb leachability in slurries. The XRD result showed the formation of CSH and Pb(OH), which facilitated the reduction of Pb leachability.
每年都需要处理大量含有重金属的疏浚泥浆，然后才能再利用；在这些受污染的泥浆中，经常会发现铅（Pb）。通常使用生石灰（CaO）-激活磨细高炉矿渣（GGBS）、氧化镁（MgO）-激活 GGBS 和普通波特兰水泥（OPC）来修复受铅（Pb）污染的土壤；然而，使用这些固化剂（或粘结剂），特别是 CaO-GGBS 和 MgO-GGBS，来处理高含水量的受铅污染的泥浆很少有报道。此外，以前的研究在使用三种粘结剂处理受铅污染的土壤的机械性能和浸出性能方面得到了不一致的结果。基于上述原因，本研究使用 CaO-GGBS、MgO-GGBS 和 OPC 处理受铅污染的粘土泥浆，并比较了三种粘结剂在改善泥浆机械性能和浸出性能方面的效果。进行了实验室试验，以检查处理后的粘土泥浆的浸出、强度、矿物学和微观结构性能。结果表明，与 OPC 相比，GGBS 基粘结剂在提高受污染泥浆的强度和铅浸出率方面更为有效。当使用合适的激活剂（CaO 和 MgO）与 GGBS 的比例时，CaO-GGBS 产生的 UCS 与 MgO-GGBS 相似，甚至更高。在处理受污染的粘土泥浆时，CaO-GGBS 和 MgO-GGBS 处理的浸出液 pH 值和铅浸出率相似。因此，仅通过比较基于相同激活剂/GGBS 比例的两种 GGBS 粘结剂，如一些先前的研究报告中所述，就断言 MgO-GGBS 在提高受铅污染土壤的强度和浸出率方面优于 CaO-GGBS，是不严谨的。铅的浸出率受 pH 值的影响，但 GGBS 的添加有利于降低泥浆中铅的浸出率。XRD 结果表明形成了 CSH 和 Pb(OH)，这有利于降低铅的浸出率。
