污泥灰微晶玻璃中重金属的浸出特性研究

Leaching characteristic of heavy metals in glass-ceramics prepared of sewage sludge residue

针对污泥热解产物污泥灰的处理处置及重金属污染问题,将其制备成微晶玻璃材料,在实现污泥灰资源化利用的同时,使重金属得以固化。结果表明,利用污泥灰制备微晶玻璃是其资源化利用的有效途径。微晶玻璃中重金属的浸出质量浓度满足《浸出毒性鉴别标准》。浸出时间、液固比和pH等均对污泥灰微晶玻璃中重金属的浸出量有一定影响,重金属的浸出量总体上随浸出时间和液固比的增加呈上升趋势,随pH的增大呈下降趋势,但其最大浸出量均远低于固体废物浸出毒性浸出标准限值。污泥灰微晶玻璃中重金属大多以稳定态存在是重金属得以有效固化的重要原因。

This paper aims to report our research results on the possibility and practice to prepare glass-ceramic products by using the by-products of the sewage sludge residue as raw material.In this paper,we suggest a five-step Tessier sequential extraction method to be adopted in glass-ceramic preparation.In our paper,we have investigated the species distribution to characterize the treating effect of the heavy metals on the horizontal vibration extraction procedure through our study of the leaching characteristics of heavy metals in glass-ceramic processing.The results of our investigation show that,when the dosage of sewage sludge residue reaches 46.6% in the raw material of preparing glass-ceramic,the potinal parameter of the glass-ceramic preparation should be： the nucleation at 645 ℃ for 30 min,the crystallization at 880 ℃ for 120 min,and then rising to nucleation temperature from the room temperature at the heating rate of 6 ℃/min and then getting to crystallization temperature from the nucleation temperature at the heating rate of 3 ℃/min.The compressive strength of glass-ceramic is 170 MPa,whereas the flexural strength should be 38 MPa,with the micro hardness being 5 GPa,the density equal to 2.7 g/cm3,the acid and alkali resistance being 0.2%,and the water absorption coming to 0.It is under the above said conditions that all the properties of the synthesized glass-ceramics can be made superior to natural marble.And it is under these conditions that can ensure the effective reuse of the sewage sludge residue.The leaching toxicity tests demonstrate that as compared with the sewage sludge residue,it has been made possible to reduce significantly the leaching concentrations of heavy metals,including those of Cu,Zn,Ni,As,Cr,Pb in glass-ceramic making.Moreover,we have made clear that the leaching time,liquid-solid ratio and pH value may all have a certain effect on the leaching concentration of heavy metals.With the increase of the leaching time and liquid-solid ratio,the leaching concentration of heavy metals can gradually increase too.But with the increase of pH,the leaching concentration of heavy metals tends to decrease,though the maximum leaching concentration remains to meet the requirements.The results of our investigation and specification analysis prove that heavy metals in the glass-ceramics resulted still come into general conformity with the stable forms like bound to organic matter and residual,which is made for the immobilization of the heavy metals.