活性污泥吸附预处理腈纶废水的机理研究

On the pretreatment mechanism of acrylic fiber sewage via the activated sludge adsorption

以活性污泥作为吸附材料,研究了其对腈纶废水COD的吸附特征。结果表明,活性污泥可吸附腈纶废水中的COD,吸附量可达135 mg/g。伪二级动力学方程能很好地描述活性污泥对腈纶废水中的COD的吸附过程,模型计算出的二级吸附速率常数(k2)为2.3×10-4g/(mg·min);Langmuir方程最适合描述该吸附过程,决定系数在0.96以上。从活性污泥吸附前后腈纶废水中的有机物相对分子质量分级结果可以看出,活性污泥对大分子(>30 k Da)有机物有较好的去除,污泥的电镜照片也证明了该点。研究表明,活性污泥吸附可去除腈纶废水中的悬浮物和胶体物,是有效的腈纶废水预处理方法。

The paper is aimed at introducing its experimental investigation and innovation of the activated sludge adsorption pretreatment measures in hoping to heighten the removal efficiency of the acrylic fiber sewage. Since it is difficult to degrade acrylic fiber sewage,it has lots of high organic matters in the form of suspended solids and colloidal particles to affect the sewage bio-treatment system. For the above said needs,we would like to focus our exploration activities on the effects of the absorbent dosage and the adsorption time through batch experiments. At the same time,we have also made a deep-going study on the adsorption kinetics and adsorption thermodynamics of the aforementioned system,whereas the equilibrium data has to be tested and made to fit for Langmuir and Freundlich models. What is more,we have also examined and tested the pseudo-first order,the pseudo-second order and the particle diffusion mode models from the point of view of the adsorption of COD to the activated sludge. Besides,wehave also inspected the distribution molecular weight（ MW） of the acrylic fiber sewage before and after working out the activated sludge adsorption data and the SEM photograph of activated sludge so as to disclose what kinds of organic compounds can be readily adsorbed on the activated sludge. The results of the above investigation and experiments prove that the adsorptive power of COD for the activated sludge in the acrylic fiber sewage accounts for 135 mg/g,while the activated sludge pretreatment can help to increase COD removal efficiency by 35% for the acrylic fiber sewage. On the other hand,the kinetic studies we have done indicate that the COD adsorption for the activated sludge turns out to be in accord with the pseudo-second order kinetic model,whose rate constant（ k2） is equal to 2. 3 × 10-4 g/（ mg·min）. Moreover,the calculation results of the isotherm studies from the equation reveal that it is possible to describe the adsorption behavior with the Langmuir isotherm model,whose correlation coefficient should be bigger than 0. 98. In addition,the molecular weight（ MW） of the tested and measured distribution of the acrylic fiber sewage before and after activated sludge adsorption also prove that the activated sludge tends to have a better removal efficiency of the organic matters with higher MW（ 30 kD a）,which can be demonstratively validated by the SEM photography of the activated sludge. From what is said above,it can be concluded that the activated sludge adsorption is indeed an effective pretreatment method in helping to remove the suspended solids and colloidal particles in the acrylic fiber sewage.