以電動力法去除下水污泥中重金屬之研究

Removal of heavy metals from domestic sewage sludge by electrokinetic process

劉婉甄(Wan-Chen Liu)

指導教授 ： 章日行

朝陽科技大學/理工學院/環境工程與管理系/碩士(2014年)

摘要

由於下水污泥中含有高營養物質和有機物，可作為堆肥、建築材料等，具有相當的經濟效益。但污水處理場所產生之污泥，除了含有上述具經濟價值成分外，尚含有重金屬與其他有毒性物質存在，若無法將污泥中這些危害物質移除，不僅無法用於農業堆肥，且需以有害廢棄物方式處理，後續處理成本亦大幅提升。若不慎排放至環境中，其導致土壤或地下水污染，影響層面與後果更是不堪設想。本研究以含重金屬之下水污泥為整治試驗之主要標的污染物，利用電動力技術將下水污泥之重金屬移除，並探討不同操作條件之影響，冀使對污泥中之重金屬達到移除之成效。
本試驗以台中某實場下水污泥為對象，首先進行下水污泥樣品採集、前處理及分析下水污泥的基本物化特性，同時選用不鏽鋼作為陰極板材料，並配製0.01 M Na2CO3做為電解液，以不同種類之陽極電極板（石墨及DSA）於電壓梯度1.5 V cm-1下進行5天的試驗。結果顯示，使用DSA為操作之電極板時有較佳之去除效率，其中重金屬鎳、鎘和鉻去除效率最為顯著，分別為72.2%、56.8%及38.6%。接著選用DSA作為陽極板，探討以不同之操作電壓進行5天之電動力試驗（1.0 V cm-1、1.5 V cm-1、2.0 V cm-1、2.5 V cm-1），結果顯示，鎘、鎳、銅和鉛於電壓梯度2.0 V cm-1時有較好之去除率，分別為100%、96.7%、17.9%及52.9%；鉻及鋅則於2.5 V cm-1時去除效果較顯著，去除率為80.1%和44.1%。
在處理成本方面，利用電動力技術處理下水污泥中重金屬，以不同操作電壓梯度（1.0 V cm-1、1.5 V cm-1、2.0 V cm-1、2.5 V cm-1）進行5天之試驗，其所花之電費分別為7元、13元、21元及31元。

關鍵字

重金屬污染物 ； 下水污泥 ； 電動力法

並列摘要

Domestic sludge contains a large number of nutrients and organic matter, which can be used as compost, construction materials, etc. However, the sludge composes a mass of harmful components such as heavy metals, pathogenic microorganism. If these hazardous substances can’t be removed from sludge, sludge not only can’t be used as the compost but also increase treatment and disposal costs. The main purpose of this study is to investigate the removal efficiency of heavy metals from domestic sewage sludge by electrokinetic process. Moreover, we discussed the removal efficiency associated with different operating conditions to find out the appropriate operational parameters.
Sludge samples were collected from the real-site of a sewage treatment plant in Taichung City. First of all, heavy metals content and the physico-chemical characteristics of sludge samples were analyzed. In the electrokenetic system, the stainless steel was served as the cathode, and 0.01 M Na2CO3 was prepared as the electrolyte solution. Different types of anode electrode plate materials including graphite and dimensionally stable anode (DSA) was respectively applied with 1.5 V cm-1 voltage gradient for 5-day treatment. Results showed that DSA anode could effectively remove the heavy metals in domestic sewage sludge; the removal efficiency of nickel, cadmium and chromium in the sludge was about 72.2%, 56.8% and 38.6%, respectively. For the consideration of DSA system, different operating voltages of electrical power (i.e., 1.0 V cm-1, 1.5 V cm-1, 2.0 V cm-1and 2.5 V cm-1) were conducted. Experimental results showed that the removal efficiency of cadmium, nickel, copper and lead, was respectively around 100%, 96.7%, 17.9% and 52.9% under the voltage gradient of 2.0 V cm-1. When the use of 2.5 V cm-1 voltage gradient was applied, the removal efficiency of chromium and zinc was around 80.1% and 44.1% respectively. Based on the above situation, the operating costs ranged from 7 to 31 dollars per 100 mg kg-1 of heavy metals.

並列關鍵字

Domestic sewage sludge ； Electrokinetic ； Heavy metals

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