評估顆粒活性碳與臭氧對飲用水中微量異臭味物質-Geosmin之去除效果

Abstract

飲用水中含有天然土霉味,一直是民眾抱怨水質不佳的主要原因之一而 geosmin則構成土霉味之主要成分,其為優氧化水中放線菌或藍綠藻的代謝 物o本論文主要之目的為針對於此微量有機物質geosmin,先建立 (Closed- loop stripping Analysis,CLSA)的濃縮技術,及GC-FID分析方法,再求其 去除技術o本研究在實驗室方面,以批式GAC吸附及臭氧氧化來評估geosmin 之去除效果,最後進行GAC管柱試驗o以上研究結果如下: 1.由吸附結果可 發現當接觸在48小時內,吸附效率隨時間增加而增加,而超過48小時則殘留 之geosmin量似乎沒有什麼改變o 2.當增加NaCl濃度從0.01M至0.1M時GAC 吸附量增加o 3.pH對於GAC吸附量影響並不顯著,但若加入腐植酸則會造成 競爭,而降低吸附量o 4.臭氧是一種很強的氧化劑並且很容易打斷分子鍵, 但是過多臭氧量,將會對吸附造成反效果,反而降低吸附量o在本實驗中以 AOD=10.2時吸附量最高o 5.最後,檢驗GAC管柱試驗所繪出之貫穿曲線相當 陡峭,其處理量為8(ng GSM/mg GAC),與批式差鉅有限,顯式GAC管柱相當適 合用來吸附geosmin分子 o Naturally occurring earthy-musty odor organics can be considered as the major sources of complaint by the consumers of drinking water. According to the results of many studies,it is found that the geosmin is one kind of earthy-musty odor products of actinomycetes or blue-green algae. The main purposes of this study are to analyze geosmin with GC-FID after concentrating it by CLSA (Closed Loop Stripping Analysis),and to seek the best method of treating geosmin. In this study, the major subjects are as follows : 1.The batch-type experiments of GAC adsorption and ozonation were conducted for the removal of geosmin in laboratory. Finally, a laboratory-scale of GAC column was designed to evaluate the parameters of the adsorption process. The results are concluded as follows: 1.The removal efficiency of geosmin by GAC adsorption increases with the increasing of time in 48 hrs,and becomes ineffective after 48 hrs. 2.The results of the experiments indicate that it is favorable in adsorption capacity to increase the NaCl concentration from 0.01M to 0.1M. 3.The pH value of solution has no major effect on adsorption capacity,but the adsorption cappacity is significantly reduced after adding humic acid. 4.Ozone is a strong oxidant and can cleave the bond of molecurlar structure easily,but excess ozone dose will produce adverse adsorptionn behavior of geosmin.In the study,the overall efficiency is best when apparent ozone dose (AOD)(mg of O3 /ug of geosmin )is 10.2 5.Finally,after the examination of breakthrough curve,we can find the GAC bed is feasible for the removal of geosmin.