以極微濾薄膜法去除水中硬度及腐植酸之研究

Abstract

本研究針對水中的硬度（鈣及鎂）及腐植酸的高級處理方法進行探討，由於此兩種物質為國內各水廠普遍存在之問題，因此希望能了解當使用薄膜高級處理法進行軟化處理時腐植酸之存在對其效果之影響，並針對水中硬度含量與煮沸水泛白及結垢的關聯性進行研究。根據這一年來對港西及澄清湖淨水廠硬度之調查結果發現，離國內之水質標準（台北300mgCaCO3/L，臺灣省500）都還有一段距離，但從本研究昇溫試驗結果指出，雖然硬度沒有超過標準，但經過著沸10分鐘後，其析出量都超過40%，造成結垢泛白，因此可以考慮使用本研究之极微濾薄膜法加以處理，以改善水質，否則煮沸水結垢泛白之問題還是無法解決，畢竟這也是民眾對自來水詬病之主因。 從極微濾薄膜法對硬度去除之研究中發現，假如原先薄膜對硬度之去除效果很好的話（如ATFRO薄膜），則氯離子對他的影響就會很小，然而，若原本效果就不是很好時（如ATFRO薄膜），單價離子之存在對他之影響將會很大，去除效果將會差上好幾倍（5.3倍），比較氯離子對本研究中之三種薄膜影響之程度，可以發現氯離子之存在對ATF50薄膜去除硬度之影響最大，ATFRO薄膜則影響最小。當固定水樣中硬度含量300mgCaCO3/L，改變添加腐植酸溶液之濃度，結果發現，對於薄膜去除硬度之影響不大，不但對硬度去除效果沒有幫助，且使得清水之殘留硬度有微量之增加。然而，硬度之存在，卻對腐植酸之去除有明顯之提高，對於DK3308T薄膜，去除率平均提高了16%，對於ATFRO薄膜，去除率平均提高8%，至於AFT50薄膜，去除率平均提高9%，因此，以DK3308T薄膜影響之最大。最後採取澄清湖水廠之水樣進行處理效果之評估，並預測其處理效果，結果發現，對於硬度及總有機碳之去除率，都能很輕易的以人工水樣之結果加以預測，誤差範圍幾乎都在5%以內。

This research concentrates on the hardness(calcium and magnesium) of the furface water and the advanced methods dealing with the humic acid. These two matters are the problems theat commonly exist in the water plants in our country. therefore, our aim is to understand the effect of humic acid when using the membrane advanced treatment method to soften the water. Furthermore, our another aim is to study the connections between the degrees of hardness in water and the scale of boiling water. Based on the survey of the hardness in the Gaangsi and Cherngching Lake water plants this year, the survey of the hardness in the Gaangsi and Cherngching Lake water plants this year, the results show that the quality of the water is still fairly below the standard of drinking water(taipai 300mgCaCO3/L,Taiwan 500). However, the result of the temperature rising experimetn in this study shows that we can consider using the nanofiltration(NF) membrane method to improve the quality of water. It is bgecause over 40% of hardness will be separated as scale after ten minutes of boiling. The problem of scaling of the boiling water will not be solved without adapting this method. This is the main complaints that people have on tap water. From the study of the NF membrane process in removing the hardness, we find that the influence of chloride ions will be subtle if the original membrane(e.g. ATFRO membrane) is effective in removing the hardness. However, if the original result was poor(e.g. ATF50), the influence of monovalent ions will be great and the outcome of the removal will make a great difference(5.3 times). Comparing the three membranes in this study, we can find that the existence of chloride ions influences the ATF50 membrane the most and the ATFRO the least when removing the hardness. When controlling the hardness in water samples as 300mgCaCO3 per liter and changing the concentration of humic acid, the influence on the membrane in removing the hardness appears to be insignificant. Not only that it is ineffective, but it also slightly increases the hardness of the permeate. Yet, the existence of the hardness has an eminent effect on removing of humic acid. For the DK3308T membrane, the removal rate arises by 16% on the average. As for the ATFRO membrane, it increases 8% and ATF50, 9%. Therefore, the influence on the DK3308T membrane is the most prominent. Lastly, the water sample from chengching Lake is used to evaluate and predict the effectiveness of the method. As a result, it is easy to predict the hardness and the removal rate of total organic carbon with artificial water samples. Furthermore, the range of error is mainly with 5%.