• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.404-410
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• 2009

In this study, research for physical and chemical characteristics were conducted through analysis of sediments, grading and heavy metals (e.g., Mn, Cu, Cd, Zn and Pb ) in sewers which are classified by drainage types. After that, cement solidification and yellow soil calcinations made heavy metals stabilized and then, ways of recycling it were examined. The grain size distribution of all sediments was relative graded. When evaluating heavy metal pollution through index of geoaccumulation (Igeo), Cu showed moderately pollution or strong pollution in forest and street site and Zn was assessed by moderately pollution in military, residential, and street site. Analysis of Pearson Correlation coefficient of heavy metal indicated that all items in street site have tight relationship respectively. Especially, Cd-Zn, Cu-Pb, Cu-Mn, and Pb-Mn have relationship at 99% confidence intervals in statistical analysis. Recycling it with cement solidification was satisfied with compressive strength standard under 55% deposit contents and Zn, Pb, Mn were stabilized effectively. If time and temperature plasticity and compressive strength would be standard, it is revealed that yellow soil calcinations is valuable aggregate when it has 50-60 Wt% contents. When considering economic feasibility and stabilization of heavy metals, cement solidification would be more appropriate than yellow soil calcinations as solution to recycling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.584-591
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• 2017

Metal removal from water has not been explained clearly by either adsorption onto the surface of absorbents or precipitation as metal hydroxides because those occur simultaneously to a certain extent. For a better understanding of the metal removal mechanisms, batch experiments were performed using soil calcined at $850^{\circ}C$ under various pH conditions for Cu, Pb, Zn, Cd, and Cr. The results showed that the metal removal efficiency with the exception of Cr decreased abruptly, even within 5 min, showing more than 90% removal. The pH of each reactant increased gradually from around 7 to 9 with time. The increases in metal removal at higher pH appear to be associated with metal hydroxides precipitation. Comparative experiments, which were carried out changing the pH by reacting with commercial activated carbon (CAC), natural yellow soil (NYS), and calcined yellow soil (CYS), showed that the pH of the CYS only increased with time. Calcination processes might lead to a change in the physical properties of the soil matrix resulting in a high pH when reacted with water. Apart from adsorption onto the surface of the absorbents, these results show that the adsorption and/or precipitation of hydroxides onto the surface of adsorbents also play important roles in regulating the dissolved metals under alkaline conditions.