含EDTA銅製程廢水之處理研究

Abstract

本研究主要處理半導體與薄膜電晶體液晶顯示器（TFT-LCD）產業所排放之銅製程廢水，其廢水含高濃度銅離子約5000 mg/L，但於製造過程中因常使用到強螯合劑EDTA用以控制銅離子濃度，導致廢水中含大量螯合銅而難以利用傳統氫氧化法予以沉澱處理，因此，本研究欲找出有效處理效率且符合經濟效益之處理含EDTA銅製程廢水方法，目標將銅離子濃度去除至1 mg/L以下。 本研究利用單一理化方法，包括Fenton氧化法、銅-鋁置換法與硫化鈉添加法，得到最佳銅離子去除率可達99 %以上，但最低銅離子濃度僅為1.8 mg/L。考量其去除效率與經濟效益後，決定以同時添加鋁片及硫化鈉之結合性理化方法，找出最佳操作條件為控制反應pH值為13、每單位克重銅添加0.5 g 60% Na2S與1.0 g 0.4 cm* 0.4 cm鋁片，於反應60分鐘後，可將溶液中銅離子濃度降至1 mg/L以下。另外，改變此股廢水之主要成分（H2O2、NH4+、NO3-、PO43-、Al3+）其濃度介於0~2500 mg/L間，結果顯示氨氮對處理之影響性最大，鋁離子濃度則影響最小，不過，結合性理化方法皆可於60分鐘內，將其銅離子濃度去除1 mg/L以下，表示此法之操作空間頗廣大。 最後，處理後之固體物主要分為兩種含銅化合物，一係具回收價值之金屬銅沉積物，另一為硫化銅汙泥，可利用臭氧將後者氧化為工業常用之硫酸銅；此外，上澄液因含大量鋁離子與EDTA，似可供為混凝劑之用途。總而言之，由本研究所設計之處理程序未來應極具實用前景。

Copper processing wastewater discharged by the semiconductor and the thin transistor liquid crystal display（TFT-LCD）industries is mainly treated in this study, and the wastewater contains high concentration of copper ion which is about 5000 mg/L. In order to control the concentration of copper ion, a strong chelating agent ethylenediaminetetraacetic acid (EDTA) is usually used in the manufacturing process, and it leads to the result that the wastewater containing amounts of chelating copper is treated hardly by traditional hydroxide method. Therefore, it is necessary to find out an effective and economical method to treat the copper processing wastewater containing EDTA, and the main objective is treating the copper ion to be less than 1 mg/L. First, this topic uses single physicochemical methods, including Fenton oxidation, copper - aluminum cementation and sodium sulfide addition method, to remove above 99% copper ion. Still, the minimum concentration of copper ion is 1.8mg/L, which does not achieve the target concentration. Considering about the copper ion removal rate and economic efficiency, the combined physicochemical method that add aluminum and sodium sulfide simultaneously is decided to use. And the best operating conditions are followings: keeping pH 13, adding 0.5 g 60% Na2S and 0.4 cm*0.4 cm 1.0 g aluminum sheets per gram of copper ion and reacting 60 minutes, and the concentration of copper ion can be removed under 1 mg/L. In addition, the concentration of the main characteristics（H2O2、NH4+、NO3-、PO43-、Al3+） in this wastewater is changed between 0~2500 mg/L, and the results appear that the influential of ammonia nitrogen is the most and of aluminum ion is the least. Nevertheless, the concentration of copper ion can be treated below 1 mg/L after 60 min by using combined physicochemical method, so it appears that the operational flexibility of this method is quite large. Finally, the produced solid includes two kinds of copper compound, one is the copper deposits with recovery value, and the other is CuS sludge which could be oxidized to industrial usable CuSO4 by ozone. And the supernatant can probably be as coagulant because of its component containing amounts of aluminum ion and EDTA. According to the results discussed above, this treatment process is feasible for treating the copper processing wastewater.