Cement and zeolite stabilization/solidification of heavy metal-contaminated sediments: 841-Day leaching characteristics, mechanisms, and microstructure

IF 7.1 2区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Waste management Pub Date : 2024-10-07 DOI:10.1016/j.wasman.2024.09.025

Nan Hu , Geng Chen , Yonghui Chen , Minguo Lin , Panpan Tang , Wanlu Zhang , Zi Ye

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引用次数: 0

Abstract

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, NH₃-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 NH₃-N by 4.23 % and 10.04 %, respectively. However, there was a risk of TN, NH₃-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 NH₃-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.

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重金属污染沉积物的水泥和沸石稳定/固化：841 天沥滤特性、机制和微观结构。

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。考虑到水泥含量、固化时间和沸石的影响，本研究通过为期 841 天的槽浸出试验研究了 S/S 沉积物的长期浸出特性和机制。结果表明，pH 值、重金属、TN、NH3-N 和 COD 之间存在明显的相关性。水泥含量为 6%、固化时间为 30 天的试样（C6(30)）表现出相当高的重金属稳定率，其中 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% 的沸石部分替代水泥（C5 + Z0.5(30)）不仅能更有效地稳定除 As 以外的重金属，还能将 COD 和 NH3-N 的释放量分别减少 4.23% 和 10.04%。不过，在长期浸滤过程中，TN、NH3-N 和 COD 仍有可能超过允许限值。显微分析结果表明，水化产物和低孔隙率有助于重金属的稳定。浸出机制显示，表面冲刷控制着铬和铅的浸出，而扩散控制着镍、铜、锌、砷、COD、TN 和 NH3-N 的浸出。考虑到稳定化性能、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。

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来源期刊

Waste management 环境科学-工程：环境

CiteScore

15.60

自引率

6.20%

发文量

492

审稿时长

39 days

期刊介绍： Waste Management is devoted to the presentation and discussion of information on solid wastes,it covers the entire lifecycle of solid. wastes. Scope: Addresses solid wastes in both industrialized and economically developing countries Covers various types of solid wastes, including: Municipal (e.g., residential, institutional, commercial, light industrial) Agricultural Special (e.g., C and D, healthcare, household hazardous wastes, sewage sludge)