有機污泥重金屬萃取評估探討

隨著污水下水道的普及、納管戶數及各工業區之污水處理廠產生污泥量逐年增加的情況下，含有高濃度重金屬污染的污泥是限制其回收應用的阻礙之一，當務之急應當降低重金屬的含量。目前臺灣污泥回收處理皆以強酸萃取出重金屬，常用方法是以無機酸萃取污泥重金屬，雖然效果顯著，但其製程廢液有污染環境之虞，且因無機酸會使污泥結構體受損並不利於後續使用。本研究從福田水資源中心(家庭)及台中港水資源中心(工廠)收集的污泥樣品，將樣品先利用室溫、冷凍、真空乾燥三種不同之前處理，將污泥與不同濃度之檸檬酸(CA)、鹽酸(HCl)與不同pH值及濃度聚麩胺酸(γ-PGA)進行萃取，分析其污泥化學型態來佐證不同酸之淋洗效果、探討萃取後是否有利用的價值及是否達到土壤管制標準，爾後進行評估重金屬去除的可行性及是否符合應用於農地之標準。本研究結果顯示，台中地區兩廠水資源中心福田及台中港污泥，以酸去除試驗發現其去除率皆以冷凍條件搭配1.0 M CA、8 hr清洗時間、固液比為1:5的條件下效果較為顯著，福田污泥去除率分別為Cd 28.7%、Cr 17.9%、Cu 4.03%、Ni 8.77%、Pb 10.2%、Zn 23.9%；台中港污泥去除率分別於Cd 22.6%、Cr 11.2%、Cu 0.07%、Ni 26.7%、Pb 12.2%、Zn 22.8%。此外，聚麩胺酸(γ-PGA)試驗中去除率皆以冷凍條件下添加pH4 1.0% γ-PGA，效果較為顯著，福田去除污泥去除率分別為Cd 13.2%、Cr 4.73%、Cu 1.01%、Ni 8.34%、Pb 1.89%、Zn 14.8%；台中港去除污泥其去除率為Cd 10.3%、Cr 4.95%、Cu 0.28%、Ni 8.52%、Pb 5.60%、Zn 14.0%。另外，型態試驗中可交換態及碳酸鹽鍵結態之含量與本試驗去除率相同，甚至將萃取劑濃度提升能去除微量之鐵錳氧化態。綜合以上結果發現從三種不同之前處理方式後添加0.5 M CA與0.5 M HCl萃取效率相近，亦可利用對環境較友善之CA取代無機酸進行萃取，降低環境破壞。

關鍵字

污泥；重金屬；檸檬酸；聚麩胺酸；冷凍處理；真空冷凍處理；序列萃取

並列摘要

As the sewerage penetration rate has been increasing year by year, the number of households is increasing gradually, and sewage treatment plant various industrial districts have the sludge quantity to increase year by year. The sludge including the highly concentrated heavy metal pollution, is limits its recycling to apply one of in barriers, therefore must reduce the heavy metal as soon as possible the content, nowadays Taiwan sludge recycling processing all leaves the metal by the strong acid extract, usually uses the inorganic acid extract sludge heavy metal, but obvious effective makes the waste liquid can destroy the environment, moreover the inorganic acid also can cause the sludge syntagma damage therefore does not favor the following use. This research collection sludge sample is from the Futian water resources center (family) and the Taiching port water resources center (factory), using the room temperature, the freezing, the vacuum drying three different ways make the sample preparation, uses citric acid of (CA), hydrochloric acid (HCl) and the different pH value and the density different density gathers the glutamic acid (γ-PGA) to carry on the sludge the extract, and the analysis sludge chemistry state comes the drip washing effect which the evidence different acid achieves, carries on the appraisal extract after the soil control standard whether has the use value, with appraisal except heavy metal whether tallies applies in the farmland standard. This research inspect Taichung area Futian and the Taiching port sludge two factory water resources center acid elimination test result discovered the elimination rate all take freezes the condition to match 1.0 M CA is remarkable, 8 hr clean time, the water and soil ratio as 1:6, under its result Futian sludge elimination rate separately in Cd 28.7%、Cr 17.9%、Cu 4.03%、Ni 8.77%、Pb 10.2%、Zn 23.9%; Taiching port sludge elimination rate separately in Cd 22.6%、Cr 11.2%、Cu 0.07%、Ni 26.7%、Pb 12.2%、Zn 22.8%, in addition gathers the glutamic acid (γ-PGA) to experiment removes rate all freezes under the condition to increase pH4 1.0% γ-PGA obviously, removes the sludge elimination rate regarding this condition Futian separately in Cd 13.2%, Cr 4.73%, Cu 1.01%, Ni 8.34%, Pb 1.89%, Zn 14.8%; In Taiching port elimination sludge Cd 10.3%, Cr 4.95%, Cu 0.28%, Ni 8.52%, Pb 5.60%, Zn 14.0%. Moreover, In the state experiment may exchange condition and the carbonate key ties condition the content to be same with this experimental elimination rate, even can remove the extracting agent density promotion the micro ferro-maganese oxidation state. Synthesizes above result to discover increases 0.5 M CA after three different front processing mode extract efficiency to be close with 0.5 M the HCl, also may use to the environment friendly CA substitution inorganic acid carries on the extract, reduces the environment destruction.