PCB工廠部份製程中需添加螯合劑以維持銅離子的濃度穩定，但螯合劑進入廢水中易與銅離子形成錯合物，導致採用一般的重金屬氫氧化物沉澱法無法有效去除廢水中銅離子，在此狀況下將會造成放流水水質超出管制標準，在本研究中希望藉由不同的加藥量與不同的處理方式，經由實驗尋求有效的處理改善方法及操作參數。 在實驗過程中利用羥乙基乙二胺(AEEA)為螯合劑，同時以人工合成廢水與實廠廢水為廢水來源，使用之沉降劑包括NaOH、Na2S與重金屬捕集劑，混凝劑則選擇氯化亞鐵及硫酸亞鐵，經由沉澱試驗與瓶杯實驗改變污染物濃度、藥品的劑量及溶液之pH值等參數，尋求對銅離子可能之去除機制與最佳操作參數。 實驗結果顯示添加氯化亞鐵及硫酸亞鐵做為混凝劑可提供鐵離子可置換羥乙基乙二胺(AEEA)螯合的銅離子，含銅離子廢水只含少量AEEA時於pH 2-6之條件下，只要添加鐵離子達一定量以上即可將銅離子去除至放流限值内。當廢水中含AEEA濃度較高時，採用硫酸亞鐵做為添加藥劑銅離子的去除效果比氯化亞鐵好。若以硫化鈉及市售重金屬捕集劑做為廢水處理之沉降劑，當添加之硫離子莫耳濃度大於水中銅離子莫耳濃度時，於很短時間內即可將廢水中銅離子去除至放流限值内。如果要獲得較佳的操作條件則應考慮，當有AEEA異常進入廢水系統時，初期可利用添加足夠濃度的硫離子方式加入系統，再以添加足夠鐵系混凝劑方式處理可得較佳處理效果。對於銅離子含量低之螯合廢水採用添加硫化鈉處理為較理想的處理方式。 For Printed Circuit Board (PCB) plants, chelating agent is frequently added into the system to maintain the Cu2+ concentration during manufacturing product process. However, the added chelating agent might suppress the Cu2+ to form settlement of Cu(OH)2. The result leads to Cu2+ concentration in effluent exceeding the limitation for environmental regulations. In this study, we used the various chemical reagents and coagulants to examine the efficiency of removal Cu2+ as chelating agent (Aminoethanolamine, AEEA) with the different concentrations are present in the wastewater. Also, the best operation parameters were experimentally determined. The target samples were obtained from wastewaters in a PCB plant and the man-made wastewater. The chemical reagents used are sodium sulfide (Na2S), sodium hydroxide (NaOH) and commercial heavy metal precipitant. The used coagulants include ferrous chloride (FeCl2) and ferrous sulfate (FeSO4). The results of chemical precipitation experiment and Jar test determine the best dose and pH for removal Cu2+ in the wastewater containing AEEA. The experimental results indicate FeCl2 and FeSO4 are used as coagulants that Fe2+ can exchange Cu2+ from AEEA in pH 2~6 solutions. The appropriate dose Fe2+ added can effectively remove Fe2+ to reach to environmental regulations in effluents. For high AEEA concentration wastewater, FeSO4 has the higher efficiency of Cu2+ removal than FeCl2 does. Regardless of pH consideration, Na2S is the best chemical agent for Cu2+ removal. The1:1 mole ratio of S2- relative to Cu2+ can reduce Cu2+ concentration below 3.0 mg/L. The best operation condition is considered that enough Fe2+ and S2- are added to the wastewater when a large of AEEA discharges into the wastewater treatment plant.
