城市污泥生物沥滤过程中重金属滤出途径的研究

LEACHING PATHWAYS OF HEAVY METALS DURING BIOLEACHING OF SEWAGE SLUDGE

以硫酸亚铁为底物,嗜酸氧化亚铁硫杆菌为沥滤微生物对城市污泥进行生物沥滤实验,并以硫酸化学沥滤污泥处理和硫酸亚铁化学氧化沥滤污泥处理为对照来分析生物沥滤过程中6种重金属(Cu、Pb、Zn、Cd、Cr、Ni)的滤出途径。根据各处理中重金属去除率和化学形态的变化,通过估算生物沥滤过程中酸溶作用和Fe^(3+)氧化作用对重金属滤出的贡献率来推测各重金属的主要滤出途径。结果表明:Zn、Cu及Cd主要滤出途径为Fe~(^(3+))氧化作用,Pb和Cr主要通过酸溶作用滤出,而Ni的滤出则由Fe^(3+)氧化作用和酸溶作用共同控制。

In this study,series of leaching experiments including bioleaching,chemical leaching of sulfuric acid and chemical oxidation leaching of Fe^（3＋）were carried out to identify removal mechanisms of six heavy metals（ Cu,Pb,Zn,Cd,Cr,Ni）during bioleaching experiment of sewage sludge. Ferrous sulfate was used as energy substrate and Thiobacillusferroxidans as dominated bacterium. Based on the analysis of variation of removal efficiency and chemical speciation of each heavy metal in sewage sludge,the main bioleaching pathway for each heavy metal during bioleaching has been speculated via calculating the respective rate of contribution from acid dissolution or Fe^（3＋）oxidation. The results showed that Zn,Cu and Cd were leached mainly due to Fe^（3＋）oxidation,and acid dissolution is the primary leaching mechanism for Pb and Cr,while the leaching of Ni was controlled by the combined action of Fe^（3＋）oxidation and acid dissolution.