多硫化鈣整治重金屬污染地下水之研究

整治重金屬污染之地下水已成為近年來急需解決的環境議題。而抽出處理是目前最主要的處理方式，然而當抽出水量龐大時，整治金額相對增加，若處理後的水無再回注，也會造成水資源的浪費。因此使用對環境影響較小且成本較低的現地處理，是較便利且更具經濟效益的整治技術。多硫化鈣為一種強還原劑，他能將六價鉻還原為三價鉻沉澱下來，因而被用於處理鉻鐵礦砂殘渣以及六價鉻污染土壤及廢水之修復，許多國外研究指出應用多硫化鈣還原六價鉻，皆顯示對六價鉻有顯著還原成效，因此本研究將使用多硫化鈣還原穩定重金屬，探討多硫化鈣對六價鉻、銅、鋅、鎳、鉛及鎘各種重金屬的去除效率，確認多硫化鈣適合處理之重金屬種類並建立最佳操作條件。本研究先進行不同多硫化鈣添加率在不同反應時間對鉛、銅水溶液的去除效率，分析結果顯示，增加反應時間雖有增加去除效率，但多硫化鈣具有快速還原穩定效果，因此增加反應時間其效果差異不大。多硫化鈣對於鉻、鉛具有快速還原去除之功效，而對鎳、鋅、鎘、銅雖也具有去除功效，但劑量過多會形成多硫化物複合物而有濃度回升情形。因此在地下水污染整治應用，較難掌控準確劑量。

關鍵字

多硫化鈣；重金屬污染；地下水；化學還原穩定法；現地處理

並列摘要

Remediation of groundwater contaminated by heavy metals has become an environmental issue that needs to be resolved in recent years. The extraction process is currently the most important treatment. However, when the amount of water pumped out is large, the amount of remediation is relatively increased. If the treated water is not re-injected, it will cause waste of water resources. Therefore, it is a convenient and more economical remediation technology to use the local treatment with less impact on the environment with lower cost. Calcium polysulfide is a strong oxidant. It can reduce hexavalent chromium to trivalent chromium and used in the treatment of chromite ore residue and hexavalent chromium contaminated soil and wastewater. Calcium polysulfide reduces hexavalent chromium and shows significant reduction effect on hexavalent chromium. Therefore, this study used calcium polysulfide to reduce and stabilize heavy metals and explore calcium sulphide to hexavalent chromium, copper, zinc, nickel, lead and cadmium. The removal efficiency of heavy metals confirm the types of heavy metals that are suitable for processing calcium polysulfide and establishes optimal operating conditions. In this study, firstly, the removal efficiency of lead and copper aqueous solutions in different reaction rates of different polysulfide calcium was studied. The analysis results showed that, with an increase in reaction time, the removal efficiency also increases but the calcium polysulfide has a rapid reduction and stability effect, though the effect is not much different. Calcium polysulfide has the effect of rapid reduction and removal of chromium and lead, but also has the removal effect on nickel, zinc, cadmium and copper, but the excessive dose will form a complex polysulfide and increases in the concentration rate. Therefore, in the application of groundwater pollution remediation, it is difficult to control the exact dose.