| 摘要: | 本研究為探討Fe0/CO2流體化床反應系統，在不同操作條件下所營造出的處理環境對於五價砷去除率之影響，研究之控制參數包括於Fe0/CO2反應程序之不同追蹤染色劑(Reactive Orange 16)入流率（60、95、125、180、310 mL/min）、與不同二氧化碳曝氣量(100、200、300 mL/min)、於流體化床程序中不同石英砂添加量(1、2、3 kg)、及不同之流體化床程序內空氣曝氣量(100、200、300 mL/min)等，並且在系統操作過程中即時監測 pH、 DO、ORP 等指標，探討於各項參數變化下，其系統中 pH、DO、ORP 以及水力停留時間上的差異。
在實驗結果顯示，於Fe0/CO2反應程序中輔以200 mL/min二氧化碳所營造出之低 pH 環境有利於五價砷之去除，且微米鐵之添加方式以分三次添加有較佳之去除效果，原因為實驗進行中砷污染物之入流量為 310 mL/min，其在Fe0/CO2反應程序中之水力停留時間約為35分鐘，而如一次添加則會造成微米鐵粉於35分鐘內即從Fe0/CO2反應程序流入至流體化床中，而造成去除率下降，另於微米鐵三次添加方式下，可見於40、80分鐘添加後，砷仍有被去除趨勢。
This study investigated the Fe0/CO 2 recirculated system coupled with fluidized sand bed reactor system under different operating conditions to determine the hydraulic parameters suitable for the removal of arsenate. The effect on hydraulic parameters were investigated using a tracking dye (Reactive Orange 16) by varying the inflow rate (60, 95, 125, 180, 310 mL / min) and the carbon dioxide bubbling rate (100, 200, 300 mL / min) for the recirculated treatment system. For the fluidized sand bed process, effect on hydraulic parameters were investigated by varying the amount of sand (1, 2, 3 kg) and the air flow rate (100, 200, 300 mL / min). The pH, DO, ORP of the system during operation were recorded in real-time.
The experimental results showed that the Fe0 /CO2 treatment system at 200 mL/min of carbon dioxide bubbling rate can create a low pH environment conducive to the removal of arsenate when using micro scale iron and at an inflow rate of 310 mL/min, its hydraulic retention time is determined to be at 35 min. This indicates that the higher removal observed in the fluidized sand bed process, due to additional adsoeption sites offered by sand, will decrease due to a higher arsenic concentration coming from the Fe0 /CO2 treatment system. When 15 g of micro scale iron is added to the Fe0 /CO2 treatment system, the observed removal at the Fe0 /CO2 treatment system is around 40% in 45 min, decrease to around 25% in 90 min and to around 20% in 120 min. However, the removal at the fluidized-sand bed is around 95% in 45 min and decrease to 85% in 90 min to 80% in 120 min, due to an increasing higher arsenic concentration from the Fe0 /CO2 treatment system. However, when 5g of micro scale iron is added three times, at an interval of 45 min, the observed removal in the Fe0 /CO2 treatment system is around 55% in 45 min, then decrease to around 50% in 60 min, then increase again to 55% in 90 min due to additional dosage of iron at 80 min. The observed removal in the fluidized san bed is around 85% in 45 minutes then increase to around 90%, due to improved observed removal in the Fe0 /CO2 treatment system and maintaining the observed removal efficiency in 90 min, then decrease to 85 % in 120 min. The result indicated that multi-step addition of micro scale iron can remove arsenate better that a single addition. |
