氧化亚铁硫杆菌生物浸出污泥中的重金属离子

为研究氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,At. f)对污泥中重金属的浸出机制,进行了空白、直接浸出(At. f)、加亚铁浸出(At. f +Fe2+)、加亚铁和硫酸浸出(At. f+Fe2++H2SO4)4组生物淋滤实验,分析淋滤前后污泥的成分和物相变化.结果表明加亚铁和硫酸浸出淋滤后Cu、Zn、Ni、Pb和Cr的去除率可分别达到90.8%、100%、87.5%、51.6%和83.3%,高于其他3种体系;定量计算和动力学拟合结果表明,5种金属在直接-间接(加亚铁)浸出中的质量含量和速率常数(k)均高于直接浸出.EDS和XRD证实污泥浸出前后样品组分主要是C(26.2%~37.5%)、O(32.5%~45.7%)和一些无机化合物(如铝盐和SiO2),生物淋滤后会造成营养元素(P和Ca)的部分流失.此外,ICP-MS分析表明其他金属(如Cd、Fe、Mn)也能同时被溶出.基于结果分析,提出FeSO4·7H2O和H2SO4的加入有助于生物淋滤系统的启动,其中Cu、Pb、Cr和Ni主要以间接浸出为主,而Zn是直接和间接浸出共同作用.

Bioleaching of heavy metals in sewage sludge using Acidithiobacillus ferrooxidans

To understand the bioleaching mechanism of heavy metals in sewage sludge by Acidithiobacillus ferrooxidans, batch experiments including blank, direct leaching (At. f), ferrous leaching (At. f+Fe2+), and ferrous and sulfuric acid leaching (At. f+Fe2++H2SO4) were conducted, and the composition and phase transformation of the sludge samples before and after bioleaching were investigated. Results showed that solubilization efficiency of Cu, Zn, Ni, Pb and Cr in ferrous and sulfuric acid leaching was 90.8%, 100%, 87.5%, 51.6% and 83.3%, which was higher than the other three systems. Moreover, quantitative calculation and kinetic study showed that the dissolved metals and rate constants (k) of the 5 heavy metals in direct-indirect (ferrous) leaching were higher than those in direct leaching. Furthermore, EDS and XRD analysis demonstrated that the sludge before and after leaching were mainly composed of carbon (26.2%~37.5%), oxygen (32.5%~45.7%) and aluminium salts and silica, but the loss of nutrient elements (such as P and Ca) was also observed. In addition, ICP-MS detection showed that other metals (such as Cd, Fe and Mn) were leached. The bioleaching process by addition of FeSO4?7H2O and H2SO4 was proposed, where the leaching of Cu, Pb, Cr and Ni in the sludge were controlled by indirect leaching, while the leaching of Zn resulted from both direct and indirect leaching.