| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 98 === 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.
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