| Summary: | 碩士 === 國立屏東科技大學 === 環境工程與科學系 === 92 === Spectacular development of local steel industry initiates an encouraging economic growth in Taiwan, but it generated about 2 million tons per year of steel slag. In the past, slag is disposed by solidification / stabilization and landfilling, and this time it is lavish of resources and does not be suitable for Taiwan. Utilization of steel slag and enhancement living environment will be the solution for tomorrow，s world, while vitalization of steel slag covers a diverse field as the improving agent for soil, raw material for cement, and absorbent of heavy metals and organic matters from waste water. Steel slags from basic oxygen furnace （BOF）and desulfurization process（De-S）were adopted as absorbent of arsenate and phosphate in waste-water treatment, because of these slags pose superior absorption capability for VA group element.
The chemical compositions of BOF slag and De-S slag were analyzed by X-ray fluorescence（XRF）, and the concentrations of arsenate and phosphate were measured by inductivity couple plasma emission spectrometer（ICP-AES） for all adsorption experiments in this study. All efforts in research are focused on the optimization of parameters including：（1）pH value：optimal removal efficiency of two different slags is at pH=5,（2） particle size：optimal particle size is over 200 mesh,（3）shaking time： optimal shaking time is 120 minutes, （4）shaking temperature：both slags have similar effect between temperature range from 20 to 50℃,（5）kinetic adsorption model：the results shows that data is good for fitting to the Langmuir isotherm adsorption model. The maxium adsorption capacity of De-S slag for arsenate and phosphate are 13.12 mg/g and 147.06 mg/g , respectively, while that of BOF slag is 3.36 mg/g for arsenate and is 125 mg/g for phosphate performs.（6）anion competing effect：Both of sulfate and chlorine ion have less affection for the absorption of arsenate and phosphate, and the result is consistent with the specific adsorption theory,（7）results of toxicity characteristic leaching procedure (TCLP)：results indicate that all heavy metals were full met to the regulation levels of TCLP regarding to Taiwan EPA.
The study shows that De-S or BOF slag can effectively remove As and P from waste-water, For concluding, the steel-making slags are powerful adsorbent to arsenate or phosphate in waste-water treatment. These two substances might be lighten used as value-adding applications in environment through this study.
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