再利用場址之垃圾焚化底渣級配料重金屬再溶出特性

Abstract

由於有許多研究者發現底渣具備與天然骨材相似的性質，已有許多國家(美國、法國、德國等)將底渣設立其標準與法規，使底渣骨材再利用於道路鋪設工程，取代天然骨材的消耗之應用。台灣目前已有多處道路場址進行底渣再利用工程，底渣埋設廠址的當地環境特性與時間年份不盡相同，因此，於台北縣萬里鄉以底渣作為六年道路路基，桃園縣龍潭鄉以底渣作為一年道路路基與未經埋設之底渣ｅ級配料進行實驗室模擬溶出試驗，藉此研究成果，了解埋設不同年份之底渣其溶出潛勢，進而可作為國內底渣應用於道路鋪設對環境影響之參考。 粒徑分佈曲線來看，底渣ｅ級配料、龍潭、萬里之粒徑分佈範圍區分為d10，d30，d65，d90，埋設時間越長，其粒徑分佈範圍越大 。基本特性分析方面，底渣ｅ級配料之重金屬總量以Zn（3200~3600 mg/kg）以及Cu（1800~2150 mg/kg）含量較高，其次為Pb（530~605 mg/kg）；龍潭一年道路底渣級配料之重金屬總量以Zn（1950~2660 mg/kg）以及Cu（1000~1310 mg/kg）含量較高，其次為Pb（405~605 mg/kg）；萬里六年道路底渣級配料之重金屬總量以Zn（700~2150 mg/kg）以及Cu（550~1210 mg/kg）含量較高，其次為Pb（350~1200 mg/kg）。動態管柱溶出試驗十天結果發現底渣ｅ級配料之pH約在11~12之間，龍潭與萬里之底渣級配料之pH約在7~9之間。三處底渣之導電度，氯離子和及TOC隨時間的增加而有明顯的下降情形，不論顆粒大小在初期溶出是最大的。在硝酸溶液pH=5(±0.5)與DI water (pH=6.82)之淋洗試驗，DI water淋洗底渣級配料其部份溶出值低於硝酸溶液淋洗試驗。底渣ｅ級配料、龍潭與萬里動態管柱試驗中，在三組底渣不同粒徑分佈範圍中，重金屬溶出量不易從顆粒中分出，較不規律。

Several studies indicated that incinerated bottom ash is a proper material for road paving. Therefore, countries, such as USA, France, Germany, etc., established guidelines for recycling incinerated bottom ash. In Taiwan, several experimental roads using incinerated bottom ash as road base were tested. To understand the effect of incinerated bottom ash to the environment, the leakage from experimental roads by leaching test were well analyzed,. We chose two roads as experimental subjects, both using incinerated bottom ash as aggregate material, one was from Wanli Township, Taipei(constructed six years ago), and the other is from Longtan Township, Taoyuan(constructed one year ago). Both of them are compared with a bottom ash. The longer the bury time, the more the particle size varies. In total amount of heavy metal, the materials of bottom ash, Experimental results showed the incinerated bottom ash from Longtan and Wanli highly contained Zn(3200~3600 mg/kg; 1950~2660 mg/kg; 700~2150 mg/kg) and Cu(1800~2150 mg/kg; 1000~1310 mg/kg; 550~1210 mg/kg), then is Pb (530~605 mg/kg; 405~605 mg/kg; 350~1200 mg/kg). The leaching test of bottom ash shows pH range between 11~12, on the other hand, Longtan and Wanli samples show pH range between 7~9. According to leaching experiments, Cl-, TOC and conductivity were decrease with time. Comparing HNO3(pH=6.82) with DI water(pH=5±0.5) as leaching solution, using HNO3 as leaching solution shows higher results in part of the experiments. In three leaching tests and different particle size distribution, there is no significant regularity of heavy metal leaching.