畜牧污泥同時好養消化及重金屬溶出程序之研究

Abstract

畜牧業污泥含有大量有機物質及氮磷等營養成分，可利用為農地肥料或為土壤改良劑，除可達到資源回收之目的，且亦有畜牧場減廢之功效。然而，畜牧業污泥的再利用，受限於含有高量重金屬，本研究中將利用同時好氧消化及重金屬溶出程序，建立不同硫粉添加量，對畜牧污泥中重金屬溶出的效果，發現硫粉添加量越高，pH 值下降的越迅速。金屬溶出效率依硫粉添加量 (1-5 g/L) 不同而有不同的溶出效率，分別是, Cu：2-61%；Zn：1-51%；Mn：10-65%；Cr：44-99% 及 Ni：27-65%。 另一方面，本研究中將改變不同固體物含量，對畜牧業污泥中重金屬溶出效果作一番比較，亦發現固體物濃度越低，pH 值下降的越迅速。金屬溶出效率依固體物濃度 (5-60 g/L) 不同而有不同的溶出效率，分別是, Cu：29-99%；Zn：96-99%；Mn：88-99%；Cr：4-99%；Ni：99% 及 Pb：0-99%。 硫粉添加量越高及固體物濃度越低，重金屬溶出的效果越佳。而有機物的消化部分，在不同硫粉添加量的實驗中，可達到 25-32%；在不同固體物濃度的實驗中，可達到 1-38%。硫粉添加量越低及固體物濃度越高，有機物的降解越不佳。

The application of livestock sludges on agricultural lands as soil conditioners or fertilizers has the benefits of resource recycling and waste minimization of livestock farm. High concentrations of heavy metal in livestock sludge limit the land application of livestock sludges. A simultaneous metal leaching and aerobic digestion process of livestock sludge was developed and the effects of sulfur concentration on this process were investigated in this study. It was found that the rate of pH reduction increased with increasing sulfur concentration. For different sulfur concentration (1-5 g/L), 2-61% of Cu; 1-51% of Zn; 10-65% of Mn; 44-99% of Cr and 27-65% of Ni were leached from livestock sludge in this study. On the other hand, the simultaneous metal leaching and aerobic digestion process of livestock was investigated into the effect of solid concentration. It was found that the rate of pH reduction decreased with increasing solid concentration. For different solid concentration (5-60 g/L), 29-99% of Cu; 96-99% of Zn; 88-99% of Mn; 4-99% of Cr and 99% of Ni; 0-99% of Pb were leached from livestock sludge in this study. The process with more sulfur concentration and lower solid concentration had higher rate and efficiency of metal solubilization. On the other hand, 25-32% of organic matters in livestock sludge were reduced for different sulfur concentration and 1-38% for different solid concentration. There was a decrease in organic matter reduction as the sulfur concentration increased and solid concentration decreased.