| Summary: | 碩士 === 國立宜蘭大學 === 環境工程學系碩士班 === 103 === Liquid fertilizer obtained through kitchen-waste composting was found that it has the ability of removal of heavy metals from a soil by its high organic content. Both Ca2+ and Mg2+ have also been identified that they could replace heavy metals adsorbed on soil particles in neutral and acidity. A soil with severe contamination (termed Soil I), containing Cr (918 ppm), Cu (1015 ppm), Zn (1105 ppm), and Ni (529 ppm), as well as another soil with moderate contamination (termed Soil II), containing Cr (842 ppm), Cu (595 ppm), Zn (661 ppm), and Ni (751 ppm), were collected for reclamation in this study through the treatment of soil washing. Washing reagents were prepared by mixing CaCl2 and MgCl2 with the dissolved organic matter (DOM) solution, which was diluted from the liquid fertilizer. The removals of Cr, Cu, Zn, and Ni were examined when the washings were conducted for 60 min twice with 1:80 (S/L) and 100 rpm shaking at pH 2.0 and 40°C. Approximately 29.7%, 80.6%, 86.9%, and 77.6% of Cr, Cu, Zn, and Ni were removed from Soil I, respectively; about 16.2%, 98.1%, 74.3%, and 33.3% of Cr, Cu, Zn, and Ni were respectively removed from Soil II. The results also identified the addition of Ca2+ and Mg2+ encouraged the removal of metals. The maximum removal was obtained after the washing employing the mixture of 0.2M CaCl2/0.2M MgCl2/DOM. When Soil I was treated with this mixture, the removals of Cr, Cu, Zn, and Ni were respectively increased 5.5%, 9.1%, 16.8%, and 27.0% in comparison to that obtained by the same treatment but without any addition of Ca and Mg.
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