Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China; Suzhou Institute of Hohai University, SuZhou 215100, China; Jiangsu Research Center for Geotechnical Engineering Technology, Hohai University, Nanjing 210098, China.
Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China; Suzhou Institute of Hohai University, SuZhou 215100, China; Jiangsu Research Center for Geotechnical Engineering Technology, Hohai University, Nanjing 210098, China.
Waste Manag. 2024 Dec 15;190:306-317. doi: 10.1016/j.wasman.2024.09.025. Epub 2024 Oct 7.
The long-term effectiveness of stabilized/solidified sediments (S/S sediments) is increasingly attracting attention. This study investigated the long-term leaching characteristics and mechanisms of S/S sediment through an 841-day tank leaching test, considering the influence of cement content, curing time, and zeolite. The results indicate significant correlations among pH, heavy metals, TN, NH-N, and COD. The specimens with 6 % cement cured for 30 days (C6(30)) demonstrated considerable heavy metal stabilization, with stabilization rates for Cr, Ni, Cu, Zn, As, and Pb reaching 99.81 %, 99.06 %, 98.93 %, 99.61 %, 97.58 %, and 99.97 %, respectively. Compared to C6(30), partial replacement of cement with 10 % zeolite (C5 + Z0.5(30)) not only more effectively stabilized heavy metals except As, but also reduced the release of COD and NH-N by 4.23 % and 10.04 %, respectively. However, there was a risk of TN, NH-N, and COD exceeding permissible limits during long-term leaching. Microscopic analysis results suggested that hydration products and low porosity contributed to stabilization of heavy metals. Leaching mechanisms was revealed that surface wash-off controls the leaching of Cr and Pb, while diffusion controls the leaching of Ni, Cu, Zn, As, COD, TN, and NH-N. Considering stabilization performance, cost and carbon emissions, C5 + Z0.5(30) is an effective strategy for reducing long-term environmental risks of S/S sediments.
稳定/固化沉积物（S/S 沉积物）的长期有效性越来越受到关注。本研究通过为期 841 天的罐式浸出试验，考虑水泥含量、养护时间和沸石的影响，研究了 S/S 沉积物的长期浸出特性和机理。结果表明，pH 值、重金属、TN、NH4-N 和 COD 之间存在显著相关性。养护 30 天、水泥含量为 6%的试样（C6(30)）对重金属具有显著的稳定作用，Cr、Ni、Cu、Zn、As 和 Pb 的稳定率分别达到 99.81%、99.06%、98.93%、99.61%、97.58%和 99.97%。与 C6(30)相比，用 10%沸石部分替代水泥（C5+Z0.5(30)）不仅更有效地稳定了除 As 以外的重金属，而且还分别减少了 4.23%和 10.04%的 COD 和 NH4-N 的释放。然而，在长期浸出过程中存在 TN、NH4-N 和 COD 超过允许限值的风险。微观分析结果表明，水化产物和低孔隙度有助于重金属的稳定。浸出机理表明，表面冲刷控制 Cr 和 Pb 的浸出，而扩散控制 Ni、Cu、Zn、As、COD、TN 和 NH4-N 的浸出。考虑到稳定性能、成本和碳排放，C5+Z0.5(30)是降低 S/S 沉积物长期环境风险的有效策略。
