半導體高濃度廢水之高級氧化處理與有機廢液之異丙醇回收

Advanced Oxidation Treatment of High-Strength Semiconductor Wastewater and IPA Recovery from Waste Organic Solution

王春盛(Chuen S. Wang)

指導教授 ： 林勝雄

元智大學/工程學院/化學工程與材料科學學系/碩士(2002年)

摘要

半導體製程中，晶元的清洗需使用大量之異丙醇(Isopropyl Alcohol, IPA)，這些清洗過後之IPA即形成成分複雜及難處理之廢水。本論文研究之半導體廠的廢水可分為兩類。第一類之廢水含有很高濃度的化學需氧量(Chemical Oxygen Demand, COD)，約50,000 mg/L及少量之IPA，其濃度小於15,000 mg/L。而第二類為有機廢液，溶液中含有70％以上之IPA。根據這兩種不同性質之廢液探討可行有效的處理程序。
第一類半導體高濃度的廢水採用的處理步驟包括有氣提法(Air Stripping)、蒸發法(Evaporation)及芬頓法(Fenton)。第一步之氣提法可將廢水中少量之IPA回收。第二步則以蒸發的方法將廢水中之水份及沸點較低之有機物蒸出，可得到COD值較低之冷凝液與少量高COD值之濃縮液。濃縮液因量少且高COD值故建議以焚化法處理，本篇論文不再作更深入之研究，而冷凝液則以芬頓氧化法處理。工廠廢水經這些步驟的處理，COD可降至現行排放標準以下(<100 mg/L)。
論文中對芬頓氧化法進行不同變因的探討，變因有水樣起始pH值、過氧化氫加藥量、氯化亞鐵加藥量與反應溫度，在最佳之反應條件下，150分鐘即可去除COD至100mg/L以下。並以總和動力學(Lumped Kinetics)與通式反應動力學(Generalized Kinetics)兩動力學模式探討芬頓反應的機制。
第二類IPA廢液是以氣提法將IPA回收，利用批次實驗對氣提時間、氣提溫度、空氣流量及冷凝溫度等變因進行探討。實驗結果顯示，增加氣提溫度、空氣流速對IPA回收效率有相當的助益，而增加氣提時間與減低冷凝溫度可提升回收率。工廠廢液經氣提處理後可獲得較純之IPA溶液，可減低後續處理之困難度。
此外，在回收IPA過程中，有少部分之IPA逸散至大氣中，故在冷凝之外需輔以活性碳纖維的吸附，將逸散之IPA吸附回收，以防止空氣之污染。達到IPA的完全回收。

關鍵字

半導體高濃度廢水 ； 高級氧化處理 ； 異丙醇回收

並列摘要

In a typical semiconductor manufacturing process, a large amount of isopropyl alcohol (IPA) is used for wafer cleaning. The wafer cleaning process invariably generates a large quantity of wastewater that contains complex and refractory organic compounds. In general, the wastewater can be divided into two types. The first is a high-strength wastewater with a chemical oxygen demand (COD) as high as 50,000 mg/L and a small amount of IPA. The second is a waste organic solution containing over 70% IPA and fewer refractory organic components. The present research is to adopt two treatment proper procedures for dealing these wastewater and waste solution. Experimental tests are conducted to study their treatment feasibility and efficiency and to identify the optimum operating condition.
The treatment process for tackling the high-stream wastewater consisted of air stripping, evaporation and Fenton oxidation. Air striping was intended to recover as much as possible the IPA in the wastewater. The air stripped wastewater was then separated into two parts by evaporation. The residual portion became much viscous and was strongly colored compared to the original wastewater. Due its small amount (less than 3% of the original wastewater), the residue could be conveniently incinerated. The condensate was then treated by Fenton oxidation to the discharge standard. Tests were conducted to examine the effects of pH, amount of hydrogen peroxide (H2O2), ferrous sulfate (FeSO4) and operating temperature on the oxidation efficiency. Various kinetic models were employed to the test date and to describe the reaction mechanisms.
The waste organic solution contained over 70% of IPA. Hence IPA recovery became a primary focus. Air stripping was used to remove IPA form the waste solution. The gas mixture passed through a condenser that was maintained below -5℃ and was able to remove over 75% of IPA from the gas mixture. The remaining IPA in the lean gas mixture went to a activated carbon fiber (ACF) column for further IPA recovery. The combined air stripping, condensation and ACF adsorption was able to recover over 98% of IPA in the original waste organic solution.

並列關鍵字

High-Strength Semiconductor Wastewater ； Advanced Oxidation Treatment ； IPA Recovery

參考文獻

Bishop, D. F., Stern, G., Fleischman, M. and Marshall, L. S., “Hydrogen Peroxide Catalytic Oxidation of Refractory Organics in Municipal Waste water,” Industrial and Engineerung Chemistry Process Design Development, 7, 110-117 (1968)

Brasquet, C., and Le Cloirec, P., “ Adsorption onto Activated Carbon Fibers: Application to Water and Air Treatments,” Carbon, 35, 1307-1313, 1997.

Buragohain, P. N., Gill, W. N. and cramer, S. M., “Novel Resin-based Ultrapurification System for Reprocessing IPA in the Semiconductor Industry ” Industrial and Engineerung Chemistry Research, 35, 3149-3154 (1996)

Duarte E. A. and Neto I., “Evaporation Phenomenon as A Waste Managent Technology” Water Science and Techlogy,” 33(8), 53-61 (1996)

Foussard, J. N., Debellfontaine, H. and Besombes-vailhe, j., “Efficient Elimination of Organic Liquid waste: wet Air Oxidation,” Journal of Environmental Engineering, ASCE, 115, 367-385 (1989)