| 摘要: | 近年來我國逐漸提高下水道普及率，同時也衍生出數量龐大的污泥，急待妥善之處理與資源化。本研究利用台北市迪化污水廠之厭氧下水污泥餅作為製備吸附劑之原料，利用一階段化學活化法裂解都市下水污泥製備吸附劑，並探討活化劑量、碳化時間與溫度等變數對吸附劑性質之影響，隨後以重金屬鉛、鎳、銅、鎘及鋅之吸附量為指標，建立最佳吸附劑之製備條件，以提供下水污泥資源化之可能方向。 根據本研究XRD圖譜結果指出下水污泥物種型態以quartz為主，此外還存在著少量的albite、anorthite、kaolinite、illite及Fe phosphate hydrate等物種。根據FTIR結果分別說明當波數1000-1260 cm-1處會有C-O或O-H鍵結，在2800-3000 cm-1處可觀察C-H鍵結，3200-3600 cm-1則有N-H或O-H震動。 最佳吸附劑製備條件部分，當每單位汙泥可吸收4毫莫耳的KOH，碳化時間為1小時，碳化溫度為600℃，此時所製備出的吸附劑產率為63.39 %，BET比表面積為235.86 m2/g，對重金屬鎘、鉛、鋅、銅及鎳吸附量依序為16.95 mg/g、28.26 mg/g、11.92 mg/g、16.25 mg/g及20.94 mg/g。 就吸附環境而言，吸附量因pH上升而增加，較佳的環境為pH=6 (pH=1-6)，此外當重金屬溶液初始濃度增加，吸附量也隨之增加，利用Langmuir吸附模式可算出鎘、鉛、鋅、銅及鎳之理論最大吸附量分別為22.47 mg/g、35.71 mg/g、14.49 mg/g、24.21 mg/g及29.76 mg/g。 本實驗成果顯示，以KOH活化法裂解都市下水污泥製備吸附劑，不但可解決大量污泥待處理之問題，同時製備出具經濟效益之吸附劑，為一具有發展潛力之技術。 The buildup of sewer system in Taiwan has resulted in the increasing generation of sewage sludge. For environmental concerns, the recycling of sewage sludge has been in great demand in the nation. This study investigated the preparation of activated carbon adsorbent, by using anaerobic sewage sludge from Dihua Sewage Treatment Plant as a starting material, and adopting a one-stage carbonization-activation pyrolysis process. The feasibility study focuses on the effects of operational parameters, such as pyrolysis time, temperature, and concentration of activator (i.e., KOH), on the characteristics of the carbonized adsorbent. The results indicate that quartz was identified by XRD technique as major crystal species in the starting sewage sludge, while with the presence of small amounts of albite, anorthite, kaolite, illite and Fe phosphate hydrate. As shown by FTIR spectrum of the carbonized sludge, C-O and O-H bonds were identified at wavenumber 1000-1260 cm-1, and C-H bond at 2800-3000 cm-1, as well as N-H and O-H at 3200-3600 cm-1, respectively. The carbonized sludge with high sorbent performance could be obtained by heating the KOH-treated (i.e., soaked with 4 mmole KOH per gram of dry sludge) sludge at 600 ℃ for one hour. This yielded 63.39 w/w% carbonized adsorbent, with a BET surface area reaching 235.86 m2/g. Moreover, the adsorption performances, as tested by Cd, Pb, Zn, Cu, and Ni, (i.e., at an initial heavy metal concention of 1000 mg/L, and pH<1) were ranged from 16.95 mg/g, 28.26 mg/g, 11.92 mg/g, 16.25 mg/g to 20.94 mg/g, respectively. The adsorption capacities of the carbonized sludge adsorbent, however, was pH-dependent (i.e., optimum at pH=6 in the tested range pH=1-6), and increased with increasing initial concentration of heavy metal. In this study, the maximum theoretical absorption capacities as estimated by Langmuir model for Cd, Pb, Zn, Cu, and Ni were found to be 22.47 mg/g, 35.71 mg/g, 14.49 mg/g, 24.21 mg/g, and 29.76 mg/g, respectively. The results of this study suggest that preparation of carbonized sludge adsorbent, using sewage sludge as starting material and adopting a one-stage pyrolysis with KOH as activator is not only technique feasible but also material recycling-benificial. |
