天然有機物親疏水性對外加電場薄膜程序之積垢影響研究

Influence of hydrophobicity of Natural organic matter on the fouling of Electrically enhanced membrane filtration

王耀晟(Yao-Cheng Wang)

指導教授 ： 李公哲

國立臺灣大學/工學院/環境工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01935

摘要

摘要
本研究將腐植質以DAX-8樹脂分離成親水性與疏水性水樣，進行UF薄膜外加電場掃流過濾程序，並且於3種不同膜孔大小之薄膜及施加4種電場強度下進行實驗操作，於未施加電場的情況下，親水性水樣的通量衰減大於疏水性水樣，薄膜膜孔大者通量衰退程度大於膜孔小者，腐植質去除率方面是膜孔小者去除率高，親水性水樣則因較易積垢反而使去除率高於疏水性水樣，以阻力串聯分析積垢情形，發現親水性水樣主要造成不可逆積垢，而疏水性水樣則是可逆與不可逆積垢較為平均，故在清洗操作上，疏水性水樣與親水性水樣相較，更具工程應用優勢。
於施加電場的情況下過濾腐植質，過濾通量隨電場強度增加而增高，薄膜積垢阻力藉由施加電場所引起電泳動作用有效減少，分析積垢形式發現電場作用使親疏水性水樣之總積垢阻力均可減少，去除率方面隨電場增高而提升，顯見電泳作用使膜面腐植質濃度降低，因此能提高薄膜對NOM的去除，但即使於高電場強度作用下，去除率仍與薄膜膜孔大小高度相關，顯示於外加電場程序下，膜孔大小仍是影響去除率高低的重要因素，但施加電場能輔助提高去除率；不同親疏水性水樣於外加電場程序的表現不論是減緩積垢進而增加過濾通量或是提升去除效率的表現，都是疏水性水樣比較優異，與粒子電泳動試驗比較，發現疏水性水樣粒子電泳動能力較高，推論粒子電泳動能力與薄膜外加電場程序之成效具正相關性，結論是此薄膜外加電場程序適合處理電泳動能力較高的疏水性水樣，可以明顯提高過濾通量及去除效率，且就總淨出水量加以評估，疏水性水樣則較親水性之水樣可有效增加，故對原水中之腐植質成分含疏水性NOM比例較多之情況下，更顯外加電場之UF薄膜過濾應用潛力。
關鍵字：天然有機物、親疏水性、外加電場薄膜程序、膜孔大小

關鍵字

天然有機物 ； 親疏水性 ； 外加電場薄膜程序 ； 膜孔大小

並列摘要

Abstract

In this study, NOM fractionation by DAX-8 resin has been used to obtain hydrophobic and hydrophilic NOM solution. The effect of hydrophobicity on electric enhanced membrane process under three pore sizes of membrane and different electric field strength were investigated. When electric field was not applied, hydrophilic NOM solution caused more flux decline than hydrophobic one. The flux decline was getting worse with increasing pore size, while the NOM rejection was getting better with decreasing pore size. Besides, hydrophilic NOM solution resulted in significant NOM rejection due to the greater fouling as compared to the hydrophobic sample. Through the calculation of series resistance for membrane, it was observed that the hydrophilic components largely contributed to irreversible resistance but the reversible/irreversible resistance caused by the hydrophobic components was quite similar. Membrane cleaning operations such as backwash, chemical cleaning were more economical for hydrophobic NOM solution. Accordingly, hydrophobic NOM solution is more applicable to water treatment than hydrophilic one.
When an electric field was applied, flux increased with the strength of the electric field. Direct current electric field could be used to reduce the fouling resistance by the electrophoresis effect. By analyzing the fouling resistances, the total fouling resistances of hydrophobic and hydrophilic NOM solutions were both reduced with the electric field. Under the electric field, NOM rejection was increased because electrophoresis decreased the NOM concentration on the membrane surface. Additionally, NOM rejection depended on the pore size of membrane, even if a high electric field was applied, so the pore sizes of membrane appeared to be another important factor affecting the rejection ratio. With regard to the flux increase, the fouling reduction, and the rejection ratio enhancement under the electric field, the proposed method is more suitable for hydrophobic NOM solution. Moreover, compared with the experiment of electrophoresis, the electrophoretic mobility of hydrophobic components is higher than that of hydrophilic ones, and a positive correlation between the electrophoretic mobility and the performance of electrically enhanced membrane filtration was recognized. Our experimental results showed that the electrically enhanced membrane filtration can handle hydrophobic components where electrophoretic velocity is faster. Under these conditions, the electric field enhanced filtration process improves the removal efficiency and the filtration flux obviously. Hydrophobic water could also increase the total volume of permeate than hydrophilic water. Consequently, the electric field enhanced filtration has great potential for rejection of NOM containing more hydrophobic components.
Key words: Natural organic matter; NOM; Hydrophobicity; Electric enhanced membrane process; pore sizes

並列關鍵字

Natural organic matter ； NOM ； Hydrophobicity ； Electric enhanced membrane process ； pore sizes

參考文獻

李欣樺 (2004). "消毒副產物有機前質對外加電場薄膜程序之積垢影響研究." 國立台灣大學環境工程研究所碩士論文.

Adamson, A. W. and A. P. Gast (1997). "Physical Chemistry of surfaces." Wiley-Interscience, New York.

Aiken, G. R., D. M. McKnight, et al. (1992). "Isolation Of Hydrophilic Organic-Acids From Water Using Nonionic Macroporous Resins." Organic Geochemistry 18(4): 567-573.

Amy, G. L., R. A. Sierka, et al. (1992). "Molecular-Size Distributions Of Dissolved Organic-Matter." Journal American Water Works Association 84(6): 67-75.

Aoustin, E., A. I. Schafer, et al. (2001). "Ultrafiltration of natural organic matter." Separation And Purification Technology 22-3(1-3): 63-78.