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

Study on the Effects of DBP Precursors on Fouling Electric Enhanced Membranes

李欣樺(Hsin-Hua Lee)

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(2004年)

https://doi.org/10.6342/NTU.2004.01017

摘要

本實驗採用外加電場超過濾薄膜程序處理天然有機物模擬水樣腐植酸，使用GFC分離法依分子量將水樣分為G1-25,000〜3,000 Da、G2-3,000〜500 Da、G3-500〜50 Da三群，並探討在不同壓差與電場操作下之薄膜效率。
在47 kPa、74 kPa、98 kPa壓差過濾未分離之腐植酸，壓差越大通量衰退越嚴重，衰退程度分別為初始通量的85 %、78 %、72 %，並對於腐植酸的去除率亦略有衰減；當使用阻力串聯模式分析亦發現不可逆阻力所占比例隨壓差升高而增加，而可由6 % 升高至21 %。
在固定壓差為98 kPa之5小時操作下，分子量最小的G3群組通量衰最嚴重，衰退至僅有初始值的50 %，而衰退趨勢分別為G3 > G2 > G1 ≒未分離腐植酸。因G3群組分子量小較易穿透膜孔達濾液端，故UV254去除率也僅達70 %，DOC只達47 %；雖小分子群組通量衰退較嚴重，但可逆阻力與弱不可逆阻力所占比例為33 %，比G1群組的12 % 高出甚多，故較高頻率的反沖洗可改善積垢現象。
外加電場由於電泳動與電滲透的作用，在電壓25 V之操作下，對於不同的分子量群組，其通量均可維持在未外加電場初始通量值80 % 以上，SUVA值也比未外加電場時低了一倍，足見外加電場對有機前質之去除有其潛力；但在壓差為98 kPa而電壓為50 V操作下，卻有薄膜效能較25 V差之現象，此與高壓差與高電場的交互作用有關。

關鍵字

腐植酸 ； 外加電場薄膜程序 ； 阻力串聯模式 ； 分子量分布

並列摘要

The effect of humic acid size distribution as electric enhanced membrane process under various membrane pressure and electric voltage was investigated. Humic acid solution was divided into three groups, namely G1-25,000~3,000 Da, G2-3,000~500 Da and G3-500〜50 Da, by means of gel filtration chromatography according to their apparent molecular weight. Ultrafiltration behaviors were analyzed by the resistance-in-series model.
The results showed that flux declined to the extend of initial flux 85%, 78% and 72% with pressure under 47 kPa, 74 kPa and 98 kPa, respectively. Resistance in series model also revealed that irreversible resistance raised from 6 % to 21%. Besides, humic acid removal efficiency decreased with pressure increase.
While treating various molecular size solution at pressure 98 kPa. The order of flux decline was G3> G2 >G1≒ unfractionated solution. It was believed that smaller solute with stronger adsorption to the membrane pores caused serious membrane fouling and flux decline. Smaller molecular could easily pass through 100k Da membrane, thus UV254 and DOC removal efficiency was only 70 % and 47 %, respectively. However, the reversible and weak reversible resistance of the smaller molecule was 33 %, which was higher than 12 % of G1 group. Thus, frequent backwash was a promising way to deal with smaller solute.
When operating the electric enhanced membrane process, electrophoresis and electroosmosis are the main mechanism to enhance the filtration process. Adding 25 V to the system could keep the flux greater than 80 % of initial flux without electric enhanced. Besides, it has capability to reduce NOM precursors containing in permeate. As a result, the electrical enhanced membrane process has the potential for drinking water treatment.

並列關鍵字

Resistance in series model ； Molecular size distribution ； Humic acid ； Electric enhanced membrane process

參考文獻

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