以新穎緩釋型過硫酸鹽藥錠整治受三氯乙烯污染之地下水

本研究以包覆藥錠為概念，結合過硫酸鹽及纖維素處理受三氯乙烯(trichloroethylene, TCE)污染之地下水，利用纖維素膨溶之特性，研發出可長時間緩釋過硫酸鹽藥錠。本研究目的為：(1)評估過硫酸鹽藥錠、硫酸亞鐵藥錠、檸檬酸/亞鐵藥錠以及整合型整治藥錠釋放效率；(2)取得藥錠之最佳配比；(3)評估過硫酸鹽藥錠對TCE之處理成效；及(4)評估纖維素之生物降解性。實驗結果顯示，單純過硫酸鹽藥錠釋放天數可達到11天，在添加硫酸亞鐵及檸檬酸的情況下，可有效活化過硫酸鹽，且檸檬酸可以抑制硫酸亞鐵過度釋放，避免過硫酸鹽大量消耗，造成藥劑使用之浪費。過硫酸鹽整治藥錠之最佳配比為過硫酸鹽：纖維素 = 1：1 (wt:wt)，其釋放率平均每日為2,400 mg/L；整合型整治藥錠之最佳配比為過硫酸鹽：纖維素：硫酸亞鐵：檸檬酸= 1：1：0.01：0.01 (wt:wt:wt:wt) 其釋放率平均每日為2,430 mg/L。纖維素可於好氧及厭氧條件下，被現地微生物降解，在150天的條件下，土壤好氧生物降解率可達67%，污泥好氧生物降解率可達70%，土壤厭氧生物降解率可達58%。在管柱試驗中，置入單顆30g過硫酸鹽在濃度67 mg/L的TCE水溶液情況下，過硫酸鹽整治藥錠釋放天數可達10天，對TCE去除率可保持約45%。本研究所發展之過硫酸鹽整治藥錠可穩定釋放過硫酸鹽，釋放後所殘留之纖維素，可於地表下被現地微生物降解，為一具環境友善性之綠色整治技術。在經濟效益面，本研究之整治藥錠可達到長效穩定釋放效果，相較於傳統灌藥之工法，本研究所開發之藥錠不僅能節省人力及能源成本的開銷，更能有效緩釋氧化劑，以達到更佳的整治效果。

關鍵字

過硫酸鹽藥錠；三氯乙烯；纖維素；整合型藥錠；綠色整治

並列摘要

In this study, persulfate-releasing tablets were developed using persulfate and cellulose to remediate trichloroethylene (TCE)-contaminated groundwater. The objectives of this study were to: (1) evaluate the releasing rates of persulfate, ferrous iron, citric acid/ferrous iron, and integrated tablets; (2) determine the optimal ratios of the tablets; (3) evaluate the removal efficiency of MTBE by the persulfate tablets; and (4) assess the biodegradability of the selected cellulose. The results show that the persulfate-releasing tablets were able to release persulfate for 11 days. The addition of ferrous iron and citric acid to the tablets can activate persulfate effectively. In addition, citric acid can inhibit the over release of ferrous ion to prevent a large amount of the consumption of persulfate. The optimal ratio of persulfate-releasing tablets was persulfate:cellulose = 1:1 (wt:wt), which released persulfate 2,198 mg/L per day. The optimal ratio of integrated tablets was persulfate:cellulose:ferrous iron:citric acid was 1:1:0.01:0.01 (wt:wt:wt:wt), which released persulfate 2,430 mg/L per day. The biodegrading efficiency of the cellulose by soil bacteria and activated sludge was 67 and 70%, respectively, under aerobic conditions while 58% of the cellulose was removed by soil bacteria under anaerobic conditions during 150 days of incubation. In the column test,one the persulfate-releasing tablet 30g was able to release persulfate for 10 days.The TCE removal efficiency maintain about 45% an initial TCE concentration of 67 mg/L during the test.The developed persulfate-relasing tables are environmentally friendly and meet the aspect of green remediation.