Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand.
Centre of Excellence in Geotechnical and Geoenvironmental Engineering, Department of Civil Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand.
Waste Manag. 2020 Jan 1;101:44-53. doi: 10.1016/j.wasman.2019.09.033. Epub 2019 Oct 3.
A general approach to managing municipal solid waste is by incineration. Unfortunately, large amounts of municipal-solid-waste-incineration fly ash (MSWI FA) is produced in the process, with their heavy metals content posing further problems to the environment. One fundamental treatment of MSWI FA heavy metals is called solidification-stabilization, where MSWI FA is solidified in cement-based materials to cap hazardous elements from being released into the environment. Mortar formed from this cement mixed with MSWI FA suffer from decreased compressive strength due to their chloride and sulfate contents. Thus, pre-treatment of MSWI FA to remove these salts before producing mortar is desirable. This study investigated treating MSWI FA with deionized water, 0.01 M and 0.1 M nitric acid, and 0.1 M and 0.25 M sodium carbonate to remove chloride and sulfate. Physical and chemical structures of treated and untreated MSWI FA was studied to understand the chloride and sulfate removal mechanisms. Treated MSWI FA was used as cement replacement in mortar, and the compressive strength was tested. Results suggest that all of the treatment solutions tested in this study can equally remove chloride (around 250,000 mg/kg), but sodium carbonate can remove sulfate at the highest extent (15,821 mg/kg). In addition, mortar with deionized-water-treated MSWI FA gave the highest compressive strength. Heavy metals leaching was tested by the Toxicity Characterization Leaching Procedure (TCLP) method, with results passing the standard.
一种处理城市固体废物的常用方法是焚烧。不幸的是，在此过程中会产生大量的城市固体废物焚烧飞灰（MSWI FA），其重金属含量给环境带来了进一步的问题。一种处理 MSWI FA 重金属的基本方法是固化稳定化，即将 MSWI FA 固化在水泥基材料中，以防止有害物质释放到环境中。由这种水泥与 MSWI FA 混合制成的砂浆由于其氯盐和硫酸盐含量而导致抗压强度降低。因此，在生产砂浆之前，对 MSWI FA 进行预处理以去除这些盐是可取的。本研究用去离子水、0.01 M 和 0.1 M 硝酸以及 0.1 M 和 0.25 M 碳酸钠处理 MSWI FA 以去除氯盐和硫酸盐。研究了处理前后 MSWI FA 的物理和化学结构，以了解氯盐和硫酸盐的去除机制。将处理后的 MSWI FA 用作砂浆中的水泥替代物，并测试了其抗压强度。结果表明，本研究中测试的所有处理溶液都可以同等地去除氯盐（约 250,000 mg/kg），但碳酸钠可以最大程度地去除硫酸盐（15,821 mg/kg）。此外，用去离子水处理后的 MSWI FA 制成的砂浆具有最高的抗压强度。用毒性特征浸出程序（TCLP）方法测试重金属浸出，结果符合标准。
