Abstract:

To investigate the law of heavy metal migration and transformation during sludge pretreatment process, the sludge was treated with different amounts of Fenton reagents, and the chemical morphological changes of the heavy metals, including Zn, Cd, Mn and Ni, and the dissolution behavior in the subsequent bioleaching process were analyzed. The results showed that after Fenton treatment (Fe²⁺=1.00g/L, H₂O₂=9.00g/L), the capillary suction time decreased in a short time, but it had no significant effect on the final sludge dewatering after bioleaching. The proportion of the unstable states of heavy metals Zn, Cd and Mn increased from 37%, 84% and 79% to 90%, 93% and 84%, respectively. But there was no significant change in Ni. Furthermore, the contents of the four heavy metals Zn, Cd, Mn and Ni after bioleaching decreased from 3451.52mg/kg, 6.45mg/kg, 443.40mg/kg and 94.96mg/kg to 376.74mg/kg, 1.10mg/kg, 141.66mg/kg and 21.77mg/kg, respectively. Compared with the individual bioleaching treatment process, the residual content of these four heavy metals was decreased by 36.2%, 26.17%, 30.92% and 27.89%, respectively. The relative dissolution rates of the heavy metals in the bioleaching process were described by the kinetic equation, and the order was Mn＜Cd＜Zn＜Ni.

Key words: sewage sludge, Fenton, dewaterability, heavy metal speciation, bioleaching

摘要：

为考察污泥预处理过程中重金属迁移转化规律，通过投加不同量的Fenton试剂对污泥进行处理，分析了Zn、Cd、Mn、Ni四种重金属的化学形态变化与后继生物淋滤过程的溶出行为。研究结果表明，污泥经Fenton处理后，毛细吸水时间在短时间内降低，但对生物淋滤后最终的污泥脱水性没有显著提升作用；重金属Zn、Cd、Mn的不稳定态（弱酸提取态、可还原态）比例不同程度提高，当投加Fe²⁺=1.00g/L、H₂O₂=9.00g/L时，其比例分别由37%、84%、79%上升至90%、93%、84%，但Ni无明显变化。此外，Fenton处理污泥中Zn、Cd、Mn、Ni四种重金属生物淋滤后含量分别由3451.52mg/kg、6.45mg/kg、443.40mg/kg、94.96mg/kg降至376.74mg/kg、1.10mg/kg、141.66mg/kg、21.77mg/kg，比单独生物淋滤处理污泥重金属残余量分别降低了36.20%、26.17%、30.92%和27.89%。利用动力学方程较好地描述了生物淋滤过程中Zn、Cd、Mn、Ni四种重金属的溶出速率的相对大小，排序为Mn＜Cd＜Zn＜Ni。

关键词: 污泥, Fenton, 脱水性, 重金属形态, 生物淋滤