再生晶圓廠綜合廢水加藥策略及分流評估

Abstract

某再生晶圓廠廢水處理成果不佳，導致放流水異常及處理成本增加，經探究其廠內廢水乃由晶背研磨廢水與含氟廢水混合，形成綜合廢水再以化學混凝沉澱處理，為評估廢水是否分流處理效果較佳，故此研究藉由瓶杯試驗求得三股廢水之最佳pH值與加藥量，再依據求得之加藥量總量進行分流與否之建議。 結果顯示，晶背研磨廢水為高濁度低導電度之廢水，最佳處理pH值為7.5，添加PACl約208 mg/L，可將濁度下降99.9%。含氟廢水為低濁度高導電度之廢水，最佳處理pH值為7，當Ca/F為2時，氟離子去除率可達98%，而Ca/F>2時，過多的加藥量對氟離子去除已無經濟效益。綜合廢水為高濁度高導電度廢水，最佳處理pH值7，處理時加入52 mg/L之PACl，濁度即下降約99%，而Ca/F為1.5時，氟離子去除率達98%。因此，晶背研磨廢水與含氟廢水若採用分流處理其藥品耗用量較合流處理藥品用量高，故建議合流處理。

The performance of wastewater treatment in reclaim wafer fab is so poor that to cause the deterioration in effluent quality and treatment cost increasing. It is because in the fab wastewater is composed by the backside grinding wastewater and fluoride containing wastewater. This so-called combined wastewater is then treated by chemical precipitation and coagulation process. This study is to evaluate the possibility for triage treatment by jar testing. With this test, we can obtain the optimal pH and dosage for three kinds of wastewater in order to determine if the triage for wastewater treatment is a better option. The result shows that backside grinding (BG) wastewater exhibits high turbidity and low conductivity. It is also found that the optimum pH for BG wastewater treatment is 7.5 at 208 mg/L of PACl dosage. Its turbidity removal could reach up to 99.9%. Fluoride containing wastewater exhibits low turbidity and high conductivity. The optimum pH for fluoride containing wastewater was found to be 7. At Ca/F ratio of 2, the fluoride removal efficiency could reach up to 98%. However, ever though Ca/F ratio is higher than 2, there is no evidence to enhance fluoride removal higher than 98%. Combined wastewater processes high turbidity and high conductivity. At optimum pH of 7, it only costs 52 mg/L of PACl to reduce its turbidity about 99%. At Ca/F ratio of 1.5, the fluoride removal efficiency is up to 98%. The result shows that BG wastewater and fluoride containing wastewater spend more chemical dosage than that for combined wastewater. Hence, the combination of BG wastewater and fluoride containing for the end-pipe treatment is recommended.