城市生污泥与熟化后的污泥Cu^(2+),Zn^(2+)的吸附解吸比较

Comparative study on the adsorption-desorption behaviour of Cu^(2+),Zn^(2+) in city raw sludge and composted sludge

采用序批实验法对城市生污泥及熟化后的污泥Cu2+,Zn2+的吸附解吸特性进行了比较研究,实验结果表明:生污泥、熟污泥Cu2+,Zn2+的吸附量均随平衡质量浓度的增大而增大,而且与生污泥相比,熟污泥的吸附能力较强,吸附量较大.利用Henry型、Langmuir型、Freundlich型等温吸附模型分析了生污泥和熟污泥Cu2+,Zn2+的等温吸附数据,发现用这3种吸附模型拟合均较好,其中Langmuir的拟合系数最高,但属于假显著相关,Freundlich为描述生污泥、熟污泥Cu2+,Zn2+等温吸附过程的最佳模型.生污泥、熟污泥的解吸量与吸附量呈极显著的正相关,并且熟污泥的解吸曲线滞后于生污泥的,表明熟污泥对Cu2+,Zn2+的吸附强度较大.总体而言,污泥农用前将其熟化,能增强其固定外源Cu2+,Zn2+的能力,降低它们的生物有效性.

Laboratory batch experiments were conducted Zn2＋ in city raw sludge and composted sludge. The results to study the sorption and desorption of Cu2＋ and show that the amounts of Cu2＋ and Zn2＋ adsorbed by two kinds of sludge increased with the equilibrium concentrations. Compared with raw sludge, the adsorption capacity of composted sludge was stronger, and the adsorption quantity of composted sludge was bigger. Henry adsorption equation, Langmuir adsorption equation and Freundlich adsorption equation could well describe the isothermal adsorption processes of Cu2＋ and Zn2＋. The correlation coefficient of Langmuir adsorption equation was the biggest, but the correlation was of false significant correlation. Freundlich adsorption equation was the best in describing the isothermal adsorption processes of Cu2＋ and Zn2＋ in city raw sludge and composted sludge. There was a significant correlation between adsorption and desorption of raw sludge and composted sludge, and the desorption of composted sludge lagged behind that of raw sludge, with the result that the adsorption capacity of composted sludge was stronger. Overall, sludge-composting could enhance the sludge adsorption capacity of foreign copper and zinc and reduce the bio-availability.