- 學位論文
高級氧化技術處理薄膜液晶顯示器廠剝離液廢水
Treatment of TFT-LCD Stripper Wastewater by Advanced Oxidation
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摘要
本研究主要是探討以高級氧化技術處理薄膜液晶顯示器(Thin Film Transistor-Liquid Crystal Display , TFT-LCD)廠剝離液廢水之可行性。TFT-LCD之剝離液廢水主要成份為二甲基亞砜(Dimethyl Sulphoxide, DMSO)與N-甲基-四氫砒喀酮(N-Methyl-2-pyrrolidinone, NMP)，本研究分別利用臭氧與Fenton氧化法來探討含DMSO及NMP廢水的處理效果。 在DMSO部分，利用捲氣式臭氧反應器來進行研究，分別對臭氧濃度、pH值、捲氣葉片轉速進行實驗。臭氧濃度是決定反應速率的主要變數，實驗結果顯示濃度越高反應速率越快。pH值影響臭氧溶解水中之型態，臭氧溶解型態的差異導致氧化路徑也隨之不同。葉片轉速的提高可使臭氧溶解性增加，捲氣式反應器則大幅提升臭氧的使用率。臭氧的強氧化力結合捲氣式反應器，大幅提升臭氧氧化的實用性，在此氧化方法下DMSO可以很快速氧化分解，而且化學需氧量(Chemical Oxygen Demand, COD)的去除率也可達98%以上。 Fenton處理NMP廢水討論變數有初始pH值、過氧化氫加藥量、亞鐵加藥量、反應溫度..等對處理效果的影響。在最佳反應條件下，反應15分鐘即可完全去除NMP，但化學需氧量(COD)無法符合法定排放標準、並且反應後溶液pH值過低(pH=2)，濁度與鐵離子偏高，需結合化學混凝處理。化學混凝實驗探討pH值、PAC及Polymer加藥量對濁度的影響。回分法實驗是將經過化學混凝後的水樣混合統一食品廠廢水(比例1：2)，進行生物處理，結果顯示COD可降至現行排放標準以下(<100ppm)。 動力學方面，藉由兩種反應動力學模式來推導反應速率常數。由於DMSO之臭氧氧化處理COD幾乎完全去除，以通式動力學(Generalized Kinetics)模式可以完整描述反應路徑。Fenton氧化部分則以總合動力學(Lumped Kinetics)模式較可適切描述反應過程。
並列摘要
The research is to investigate the advanced oxidation treatment of TFT-LCD (Thin film transistor-Liquid crystal display) wastewater. This type of wastewater has two major refractory organic pollutants: Dimethyl sulphoxide (DMSO) and N-methyl-2-pyrrolidinone (NMP). The present research explores the treatment feasibility of the TFT-LCD wastewater by the gas-induced ozone and Fenton oxidation. In the treatment of DMSO, ozone oxidation was performed in a gas-induced reactor. The major operating variables studied include inlet ozone concentration, wastewater pH and mixer speed. Experimental test results indicate that the reaction rate increases with an increase in the inlet ozone concentration. Dissolution of ozone in the aqueous solution was strongly influenced by the wastewater pH that in turn affects the reaction mechanism of ozone oxidation. Gas induction created by the high-speed turbine was found to significantly enhance the ozone utilization and the oxidation efficiency. The test results clearly reveal that DMSO is rapidly decomposition by ozone oxidation and the corresponding chemical oxygen demand (COD) removal achieved in the oxidation exceeds 98%. Fenton oxidation of NMP was examined in terms of the wastewater pH, amounts of hydrogen peroxide (H2O2) and ferrous sulfite (FeSO4), reaction temperature, etc. Under appropriate conditions, NMP could be completely decomposed in just 15 min, but the corresponding COD removal was a much slower process. In addition, the wastewater pH became very slow and the wastewater turbidity and ferrous concentration were very high, implying a need of chemical coagulation. In the experimental tests, polyaluminum chloride (PAC) and polymer (an electrolyte) were beneficially employed to improve the COD and turbidity removal. The NMP wastewater effluent from Fenton oxidation was finally treated in a sequencing batch reactor (SBR). As a polishing step, the SBR method was capable of lowering the wastewater COD to below discharge standard (100 mg/L). Kinetics investigations were also conducted to establish the reaction mechanism and to determine the reaction rate of the oxidation processes. For rapid ozone decomposition of DMSO, the generalized reaction kinetic model was found to describe well the oxidation kinetics. However, for Fenton oxidation of NMP, the simpler lumped model was a better choice for determination of reaction rates.
參考文獻
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