強化混凝結合薄膜系統去除消毒程序前之水中溶解性有機質

Abstract

金門太湖鄰近城鎮飲用水安全一直是金門地區存在的問題，湖庫水中TOC為13~16 mg / L，快濾出水平均TOC分別為13.5和9.49 mg / L，慢濾出水則為11.21和7.78 mg / L，太湖淨水場處理流程對於水中溶解性有機物之去除效果有限，快/慢濾處理系統無發揮其功能，本研究以快/慢濾出水應用粉狀活性碳結合強化混凝再接續陶瓷膜過濾來提升水中溶解性有機物去除效果，選用三種常用之混凝劑：硫酸鋁、多元氯化鋁、氯化鐵，進行單次混凝和多次混凝，活性碳則選用粉狀活性碳，透過吸附動力試驗決定吸附平衡時間，藉由分析TOC、UV作為選擇最適混凝劑劑量等相關操作參數，接續將兩者結合應用探討處理效果，最後以陶瓷膜進行過濾，以固定通量操作觀察透膜壓差和滲透性係數變化。三種混凝劑中以多元氯化鋁對溶解性有機物去除效果較佳，最適劑量為200 mg / L，粉狀活性碳吸附時間為30分鐘，個別以混凝劑和粉狀活性碳作為吸附去除水中有機物的效果有限，使用粉狀活性碳150 mg / L搭配多元氯化鋁200 mg / L方式有效將快/慢濾水中TOC去除至4 mg / L以下，混凝後不沉澱直接以陶瓷膜過濾，在通量97.5 LMH及過濾時間160分鐘條件下，透膜壓差上升幅度為10 kPa，滲透性係數從8下降至5.4 LMH / kPa，符合陶瓷膜高濾水低阻塞之特性，反沖洗和化學反洗的回復性以化學反洗較佳，表示存在不可逆積垢，在操作上需要化學反洗才能有效去除積垢。

Safety drinking water has been an issue in Kin-men for a long term. Because the Tai-lake was polluted, the water plan can’t remove the dissolved organic matter (DOM) successfully. According to the result of investigation, the TOC in Tai-lake is 13~16 mg / L and the average TOC after the rapid filter are 13.5 mg / L in 2013 and 9.49 mg / L in 2014, and treated after slow sand filter are 11.21 mg / L in 2013 and 7.78 mg / L in 2014. It is obviously to see that the filtration units are unable to remove DOM. In my research, I will use powdered activated carbon(PAC) with enhanced coagulation and combine ceramic membrane to build a treatment process, in order to elevate the removal of DOM. By analyzing TOC and UV to determine the best of three kinds of coagulants ( alum, poly aluminum chloride(PACl), ferric chloride) and the adsorption time for powdered activated carbon. Controlling flux when using ceramic membrane to filtrate and observe the change of trans-membrane pressure ( TMP ) and permeability. From the experiment results, PACl has the best performance in removing DOM, the optimum dosage is 200 mg / L. The adsorption time of PAC is 30 min. By using PAC 150 mg / L with PACl 200 mg / L can successfully eliminate the TOC down to 4 mg / L to meet the standard. In the ceramic membrane system , the flux is 97.5 LMH, the TMP increase 10 kPa and permeability decrease from 8 to 5.4 LMH / kPa for filtrating 160 min. Enhanced chemical backwash is better than back wash in removing membrane fouling.