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The Influence of Electric potential Operartion on Electrokinetic Remediation for Contaminated Sediment
|作者:||林世平||關鍵字:||electrokinetic remediation;電動力復育;sediment;polarization;heavy metals;底泥;極化現象;重金屬||出版社:||環境工程學系||摘要:||
初步的模場實驗的操作電壓分別固定在16.0及24.0V，依電流的變化，將系統分為4個階段，而在第三個階段時，系統開始受到極化現象影響，主要是因為操作液呈現鹼性，因而造成沉澱物的產生。因此，本研究針對極化現象開始影響系統的時間，以增加電壓的方式，用以克服或緩和極化現象的發生，其中，test 1和2先以16.0V處理48hr後，再分別將電壓增加至24.0及32.0V，探討在第48hr增加不同電壓對系統的影響；另外，test 3先以16.0V處理96hr後，再將電壓增加至24.0V，並與test 1比較，探討在不同時間增加電壓對系統的影響。
研究結果，發現以test 3的改良方法，較其它的操作條件，分別將鋅和鉻的去除效果增加2~3倍，達32.33%及23.30%，並且有效提高時間及能源的效率。其現象主要是受到增加電壓的時間及醋酸操作液是否完全進入系統中所影響；此外，test 1及test 2的改良方法，雖然無法增加去除效果，但卻有效地縮短處理時間，達到增加時間效率的目的。
Electrokinetic process is an effective and economical remediation method; therefore, this research is to study the sediment polluted by zinc and chromium by using this technology. But the electrodes, applying electrical potential, would cause an obstacle in energy transmission and reduce the effectiveness of remediation which is known as “polarization phenomenon”.
The operation voltage in our pilot scale experiments was separately fixed in 16.0V or 24.0V, and the system can be divided into 4 stages according to the current change. The polarization phenomenon appeared at the Stage 3 that is mainly because the operation liquid became alkaline then caused the sedimentation of metal oxides. Therefore, this research is aimed to reduce the influence of polarization, by mean of increasing the voltage to overcome or ease off the happening of the polarization. Tests 1 and 2 were managed by applying 16.0V in the first 48 hours, and then increase the voltage up to 24.0V or 32.0V respectively, for exploring the influence to the system by different voltage. Test 3 was firstly managed by using 16.0V, then after 96 hours we increased the voltage up to 24.0V. The results of the Test 3 were used to compare with Test 1 for exploring the influence to the system by increasing the voltage at different time.
The result of this research indicates that the Test 3 is the most efficient among all the tests. Test 3 can increase the removal efficiency by 2~3 times, while the removal rate is 32.33% and 23.3% for zinc and chromium respectively. Test 3 is able to effectively increase the efficiency of time and energy. This result is achieved mainly by the time applying enough voltage and also because more acetic acid has entered into the sediment. Although the manners in Tests 1 and 2 are unable to increase the energy efficiency, they indeed effectively shorten the process time and achieve the purpose of time efficiency.
From these research results on the electrokinetic process, it can be found that our removal ratio of the targeted heavy metals is limited. That is mainly because the sediment is of a high buffering capacity, which caused the heavy metals accumulated in the pH transforming section. Among the zone, zinc is mainly accumulated by carbonate and Fe-Mn oxides and chromium by Fe-Mn oxides, which caused the low processing efficiency.
|Appears in Collections:||環境工程學系所|
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