GLDA淋洗参数对污泥中重金属去除效率的影响及其动力学分析

Heavy Metals Removal Efficiencies under Different Leaching Conditions by GLDA and Kinetics Evaluation in Sludge

  • 摘要: 采用GLDA作为淋洗剂对工业污水污泥进行淋洗,确定淋洗的最优参数,为治理工业污泥提供参考依据。通过振荡淋洗研究了GLDA浓度(0.5% ~ 20%)、pH(2 ~ 10)、液固比(10∶1 ~ 80∶1)和淋洗时间(0 ~ 24 h)对污泥中重金属去除率的影响,利用动力学方程对实验数据进行拟合。结果表明,降低pH、增加液固比和延长淋洗时间均可提升重金属的淋洗效率,在pH为2,浓度5%,液固比60∶1,淋洗时间480 min时,GLDA对污泥中的重金属淋洗率达到最优,镍(Zn)、镍(Ni)、镉(Cd)和铬(Cr)的去除率分别为91.21%、76.34%、69.56%和65.01%。准二级动力学方程可以较好的拟合GLDA对4种重金属的淋洗过程,说明重金属淋洗过程以化学淋洗为主。综上所述,在进行淋洗参数优化的基础上,GLDA可用于工业污水污泥中重金属的去除。

     

    Abstract: GLDA was used as the elution agent to leach industrial sewage sludge, and the optimal leaching parameters were determined to provide a reference for the treatment of industrial sludge. A batch sludge washing experiment was conducted to investigate the washing efficiencies of heavy metals by GLDA under the conditions of GLDA concentration of 0.5%-20%, pH of 2-10, liquid-solid ratio of 10∶1-80∶1 and leaching time of 0-24 h. The experimental data were fitted by kinetic equation. The results showed that the heavy metals removal efficiencies could be improved by decreasing pH, increasing liquid-solid ratio and prolonging leaching time. The highest removal efficiencies of Zn, Ni, Cd and Cr were 91.21%, 76.34%, 69.56% and 65.01%, respectively, under the conditions of pH by 2, concentration of 5%, L/S ratio of 60: 1, and leaching time of 480 mins. The study of the desorption kinetics showed that the four heavy metals were well-fitted to the pattern of the pseudo second-order model, indicating that the leaching process of heavy metals in sludge was dominated by chemical leaching. The results suggested that GLDA was suitable for the leaching and removal of heavy metals from industrial sludge under optimum conditions.

     

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