以兼性厭氧硫氧化菌進行重金屬污染底泥生物溶出程序之研究

Abstract

近年來許多研究指出底泥為水體重金屬主要來源，因此可預期將來會有大量疏浚後待處理的底泥。生物處理法可將底泥資源化，為現今物化處理法的取代方案。生物溶出法已被證實可有效處理含重金屬礦物，但現有研究中少有以河川底泥為處理對象，且此法有曝氣系統能源的消耗以及酸礦排水的生成等缺點。取而代之的是厭氧生物溶出法。其適用性廣、不需曝氣且不會產生較多的酸。本次實驗使用兼性厭氧硫氧化菌進行厭氧生物溶出，選定ㄧ最佳操作參數並評估厭氧生物溶出實驗的可行性。 At. ferrooxidans 以不同初始pH (2、3、4)、不同元素硫添加量(1 g/L ~ 7 g/L)、不同底泥固體物添加量 (1% - 7%)、不同植菌液添加量(5%、10%、20%)，以及將操作體積由 800 mL 提高至2 L評估運作成果。分別以初始pH 2、硫添加量5 g/L、底泥固體物添加量 1%、植菌液添加量20% 為最佳條件，以及放大尺寸後處理效果更加良好。T. denitrificans 以不同初始 pH (4-7)、不同元素硫添加量 (1 g/L-7 g/L)、不同底泥固體物添加量 (1% ~ 7%)，評估操作成果。重金屬溶出率分別以初始pH 4、硫添加量 7 g/L、底泥固體物添加量1% 最為理想。微生物活性則是以初始pH 6、硫添加量 3 g/L、底泥固體物添加量7%最為良好。 初始底泥與重金屬鍵結方式以碳酸鹽結合態為主，並且為重金屬溶出的主要因子，鐵錳氧化態次之。

Recently, a lot of researchers considered sediments as non-point sources of heavy metals pollution in waterbody. In the future, a large quantity of dredged sediments are going to be treated. Biotechnology can transform these sediments into resources which can replace physico-chemical treatment. Bioleaching (aerobic) is one of the biotechnologies that has been proved can remove or recover heavy metals from minerals and sludge, but only a few researches are using it in sediments. Besides, when bioleaching is operating, the aeration and stirring machine will increase the cost and the acid-mine drainage will become secondary pollution due to the acid production ability of microorganisms. Therefore, we use anaerobic bioleaching for removal of heavy metals from contaminated sediments. The advantages of this technology are that it is widely used for different kind of minerals, it can be operate without aeration and its low acid production are environmental-friendly as well. This research used facultative anaerobic sulfur oxidizing bacteria to operate anaerobic bioleaching in order to find out a best working parameter and evaluate the workability. This experiment used At. ferrooxidans to operate under different initial pH, sulfur dosage concentration, sediment solid dosage concentration, inoculation dosage and scale up from 800 mL to 2 L in order to evaluate the leaching efficiency. The result revealed that the best working condition is under initial pH 2, 5 g/L of sulfur dosage concentration, 1% of sediment solid dosage, 20% of inoculation dosage, and the leaching efficiency is increased when scale up. While T. denitrificans is used to operate under different initial pH, sulfur dosage concentration and sediment solid dosage concentration. The result revealed that the best working condition for metal leaching is under initial pH 4, 7 g/L of sulfur dosage concentration, and 1% of sediment solid dosage.Although this microorganism able to grow much more successful under initial pH 6, 1 g/L of sulfur dosage concentration, 7% of sediment solid dosage. Initial sediment is combine with heavy meatals mainly by carbonate, and the kind of boundary is the most important factor to meatal leaching. Heavy meatals combined with Fe/Mn oxides is the secondary.