本研究旨在利用淨水污泥餅吸附廢水中的磷，藉以評估淨水污泥餅之再利用性。實驗中以平鎮淨水場之淨水污泥餅做為吸附材料，並以人工含磷廢水及光電業實廠含磷廢水為對象，探討磷的吸附行為。研究中先採用人工含磷廢水進行等溫吸附和吸附動力實驗，探討各種操作條件對淨水污泥餅之磷吸附容量與吸附平衡時間的影響；再以批次反應槽和連續流管柱操作方式，實際應用淨水污泥餅去除光電業實廠廢水中的磷，驗證淨水污泥餅處理實廠廢水中磷之可行性。 等溫吸附實驗結果顯示，在反應溫度25 ℃、初始pH值為2.5、初始磷濃度200 mg P/L，最大吸附容量(qm)為37.88 mg P/g。Freundlich、Langmuir和B.E.T.等溫吸附模式皆可模擬本研究之實驗結果，其中Freundlich吸附模式較合適於描述淨水污泥餅對磷之吸附行為。吸附動力實驗結果顯示，當吸附劑量提升、初始pH值為酸性及初始磷濃度低時，吸附反應速率快，吸附平衡時間約為6小時。淨水污泥餅吸附磷，為一吸熱反應。反應速率與各操作因子的關係，符合假二階動力模式。由反應後溶液pH值變化可以推論，淨水污泥餅表面氫氧官能基置換水中磷酸鹽為除磷之主要反應機制。 淨水污泥餅處理光電業實廠廢水之試驗結果發現，在反應時間6小時的批次反應操作中，淨水污泥餅直接處理酸性鋁蝕刻清洗製程廢水，磷的去除率可達80 %，而直接處理中性pH值之ROR廢水，其去除率僅為25 %；當調整ROR廢水pH值與鋁蝕刻清洗製程廢水相同時(pH=2.42)，磷去除率亦可由25 %提升至80 %。在連續流管柱反應器中，流速為0.51 cm/min，設定磷貫穿點濃度為4 mg P/L，管柱於處理鋁蝕刻清洗製程廢水和ROR廢水，分別可操作3100和60分鐘。 This study evaluated the feasibility of reusing water treatment plant sludge cake for the adsorption of phosphate in wastewater. The adsorbent material was obtained from Ping-Jan water treatment plant and the adsorption behaviors for synthetic wastewater as well as the photoelectric industry wastewater containing phosphate were studied in the experiment. Isothermal adsorption and adsorption kinetic tests were carried out for the adsorption of phosphate in synthetic wastewater in order to investigate the effect of various operation conditions on the adsorption capacity and equilibrium time. Then batch reactor and continuous flow column tests were conducted to confirm the feasibility of using sludge cake for removing phosphate from photoelectric industry wastewater. The results of isothermal adsorption test showed that the maximum adsorption capacity (qm) was 37.88 mg P/g when temperature was 25 ℃, initial pH value was 2.5 and initial phosphate concentration was 200 mg P/L. Freundlich, Langmuir and B.E.T. isotherm models described well the same experimental isotherm data. However, Freundlich equation demonstrated the best fit among the three models. The results of adsorption kinetic tests reveled that the adsorption rate was increased with the increase of adsorbent dosage, the decrease of initial pH value, and the decrease of initial phosphate concentration. In general, the adsorption equilibrium time was about 6 hrs. In addition, the adsorption of phosphate onto sludge cake was a process of endothermic reaction. The phosphate adsorption kinetic data can also be well fitted by Pseudo-Second-Order Model. During the adsorption process, the decrease of phosphate concentration accompanied with the increase of pH value in solution demonstrated that phosphate replaced OH functional group on the surface of sludge cake, which indicates that ligand exchange is the dominating mechanism for phosphate removal. The results of batch operation using sludge cake as adsorbent to treat phosphate containing wastewater in photoelectric industry indicated that 80% of phosphate removal from low pH value of aluminum etching cleaning process wastewater was obtained in 6 hrs. However, only about 25 % of P removal efficiency was reached in treating the neutral pH value of ROR wastewater. When adjusting the pH value of ROR wastewater to the same level as aluminum etching cleaning process wastewater (pH=2.42), the P removal efficiency could also increased from 25 to 80 %. The results of continuous flow column tests, carried out at flow velocity of 0.51 cm/min and breakthrough phosphate concentration of 4 mg P/L, reveled that column reactor could operate for 3100 and 60 min in removing P from aluminum etching cleaning process wastewater and ROR wastewater, respectively.
