以電場掃流過濾分離CMP廢水之研究

Corssflow Electrofiltration of CMP Wastewater

熊紀中(Chi-Chung Hsiung)

指導教授 ： 莊清榮

中原大學/工學院/化學工程研究所/碩士(2004年)

https://doi.org/10.6840/cycu200400364

摘要

目前台灣的高科技產業發展迅速，伴隨的工業廢水量亦相當龐大，也由於水資源不足的問題更突顯廢水回收之重要性。薄膜處理技術目前已逐漸的應用在工業上，且大多以掃流的方式操作，主要因為其具有傳統化學處理所不及之優點，特別是所處理後的回收水可直接應用在一般工業用水。為了提高薄膜分離的處理量，外加電場掃流過濾的方式已被多位學者提出，然而其操作特性的瞭解仍非常有限，為探討該技術在電子產業廢水之應用，本研究以自行配置之SiO2懸浮液來模擬CMP廢水進行實驗，探討電場強度及其它操作條件等對過濾的影響，並對實驗所消耗的電能作量測，評估以外加電場掃流過濾CMP廢水之可行性。
實驗結果顯示，此懸浮液以0.2 μm薄膜過濾時，在0.1~0.6 bar壓差之操作條件顯示，於低壓下增加過濾壓差，對濾速提升之幅度較大。於掃流速度0.0572~0.379 m/s操作下，提高掃流剪應對擬穩態濾速的提升僅有些微作用，但其濾速約隨電場強度提高呈線性增加。以電場強度2500及5000 操作時，平均濾速約可提高9及17倍，。將此電場強度作用下之擬穩態濾速， ，與預估值， ，相比較，前者高約25%~27%。而於脈衝電場方式操作時，其濾速約為固定電場者與未施加電場者兩濾速的平均值。
0.1~0.45 μm薄膜過濾結果之比較，顯示0.1 μm的薄膜雖其濾速較慢，但其有較佳之濾液品質，而0.2及0.45 μm二者薄膜濾速差異不大，若於一般用水回收，則以較大孔徑進行過濾最符合經濟效益。
使用電場過濾之能源效率較一般掃流過濾者為高，且所得之濾液亦符合自來水標準，可直接用於一般用水上。以實驗所得之數據作為擴大實廠處理費用之依據，以電場掃流方式處理，其成本約為33元/噸，相較於其他學者所提出的化學混凝前處理及以傳統化學混凝沉澱處理之成本，本操作明顯較有經濟效益，而未來若將規模放大，其處理的費用應將可再大幅降低，預期對此類廢水分離之工業應用有發展的潛力。

關鍵字

化學機械研磨廢水 ； 懸浮液 ； 電場過濾 ； 薄膜 ； 掃流過濾

並列摘要

Currently, the rapid growth of high technology industry in Taiwan results in a great quantity of wastewater generated and, due to the seriously deficient in the water resource, the recycling of industrial wastewater is essential for the substantial development of Taiwan. Since the filtrate from crossflow membrane filtration has a fairly good quality so that it can be recycled directly to industrial process, such a filtration has been used extensively in the process of wastewater treatment. In order to reduce both the concentration polarization and solid deposition in crossflow membrane filtration for fine suspensions, a combination of shearing action and electric field has been developed, sometimes called crossflow electrofiltration, and recognized as an effective means for improving the filtration performances. But so far, the understanding of the principles of such operation is still very limited. The objective of this study was to investigate the characteristics of electro-microfiltration of SiO2 suspensions used for the chemical mechanical polishing (CMP). The effects of electric field strength, electric field mode and other operation parameters such as crossflow velocity and membrane pore size etc. on the filtration performance were analyzed to show the potential of applying the electric field to the crossflow filtration for CMP wastewater treatment.
Experimental results showed that the crossflow velocity used in the study gives a very little effect on the filtration rate and, except under low transmembrane pressure, there is only slight increase in filtration rate with the pressure. However, the filtration rate increases significantly with the addition of electric field, as E=2500 and 5000V/m the filtration rates obtained are almost 9 and 17 times, respectively, that only by shearing action. In the E range of 2500~5000 V/m used in the study, the measured steady-state filtration rates are about 25~27 % greater than the predicted values from the theoretical model, and the average filtration rates using pulsed electric field mode are nearly the mean values between that of constant electric field and that without electric field.
Filtration behaviors from three different pore size membranes, 0.1, 0.2 and 0.45 μm, were also compared. The latter two have similar results in steady-state filtration rate.
The application of electric field for the crossflow filtration of CMP suspension not only gives a significant enhancement in the filtration rate but also improves the filtrate quality to a level better than the requirement for reuse in industry. In addition, the energy consumption per unit mass of filtrate obtained from the lab-scale electrofiltration is yet much small than that from conventional crossflow filtration, and it can be expected that the energy consumption will be further reduced as the process is scaled-up in the treatment of CMP wastewater water.

並列關鍵字

suspension ； crossflow filtration ； electrofiltration ； CMP wastewater ； membrane

參考文獻

陳冠廷，“脈衝電場掃流微過濾特性之探討”，碩士學位論文，私立中原大學化工所，中壢市（2003）

江宜蓁，“薄膜電荷量測與膜過濾電動現象分析”，碩士學位論文，私立中原大學化工所，中壢市（2003）

Akay, G., R. J. Wakeman, “Electric Field Enhanced Crossflow Microfiltration of Hydrophobically Modified Water Soluble Polymers,” J. Membrane Sci., Vol. 131, PP.229-236 (1997).

Bubolz, M., M. Wille, G. Langer, U. Werner, “The Use of Vortices for Crossflow Microfiltration: Basic Principles and Further Investigation,” Separation and Purification Technology, Vol. 26, PP.81-89 (2002).

Chuang, C. J., C. W. Fang and K. L. Tung, “Electro-Microfiltration of Colloidal Suspensions,” Sep. Sci. Tech., Vol. 38, No. 4, PP.797-816 (2003).