Hydraulic conductivity and heavy metal retention of contaminated soil treated using enzyme induced calcite precipitation method
Contamination of heavy metals are known to affect the physical and mechanical properties of soil, particularly increasing the permeability due to the decrease of dielectric constant. This could increase the risk of transmission of heavy metal contaminants and threaten environmental sustainability. H...
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| 格式: | Thesis |
| 语言: | English English |
| 出版: |
2023
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| 主题: | |
| 在线阅读: | https://eprints.ums.edu.my/id/eprint/35833/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/35833/2/FULLTEXT.pdf |
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| 总结: | Contamination of heavy metals are known to affect the physical and mechanical properties of soil, particularly increasing the permeability due to the decrease of dielectric constant. This could increase the risk of transmission of heavy metal contaminants and threaten environmental sustainability. Hen , after mitigation measures should be provided. Commonly, they are improved using conventional or alternative materials to meet the geotechnical requirement. However, most of the e materials are costly, slow and long treatment cycles and environmentally unsustainable. Recently, soil improvement using biomedication or bio-inspired techniques have gained attention due to their cost-effectiveness, sustainability and environmental friendliness. Enzymatic induced calcium carbonate precipitation (EICP) is one such technique that utilizes free urease enzyme to produce calciun1 carbonate precipitation via urea hydrolysis process. This study investigated the properties of copper mine wastes from Mamut, Lohan and Bongkud, Sabah and u ed EJCP to improve the engineering properties of heavy-metal contaminated oil. The study examined the effect of variation of cementation concentrations (0.5 M and 1.0 M), curing periods (1,3, and 7 days), degree of compaction (70 and 80 % of thE maximum dry density (MDD)) and curing temperature (5 °C, 15 °C and room) on the hydraulic conductivity, calcium carbonate content, as well a heavy metal retention. Results from the three locations indicate differences in grained particle size , acidity, specific gravity, natural moisture, organic content and heavy metal contaminant SOIL While all three locations met the requirement of EICP biocementation, Lohan ,,.a selected due to the feasible coarse-fine grain composition and lowest MDD, in addition to its risky location and higher level of contamination. To mitigate the issue of oil heterogeneity and to produce reliable soil samples with same characteristic of heavymetal contamination, a locally-sourced metal-spiked Stulang Laut was tested ,, in both Lohan. The effect of EICP in both Lohan and Stulang soils were found to be similar with higher reduction of hydraulic conductivity under higher concentration of cementation solution at 1.0 M and higher degree of compaction at 80%. The effect of curing duration can be seen as early as the first 24 hours. The precipitation rate then decreases with days, with the bigger drop observed on ]-day to 3-day curing for 0.5 M compared to 1.0 M. The highest permeability reduction is observed on ample cured under room temperature (25 °C) followed by 15 °C and 5 °C. Meanwhile, higher calcite carbonate content is observed at cementation concentration of 1.0 M. It was
calcite carbonate content is observed at cementation concentration of 1.0 M. It \\ as |
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