粉末活性污泥处理含铀废水的特性

以生活污水处理厂剩余活性污泥为原料,制备粉末活性污泥(PAS)作为生物吸附剂,考察pH值,PAS投加量,U(Ⅵ)初始浓度和吸附时间对PAS吸附U(Ⅵ)的影响,探讨了PAS吸附U(Ⅵ)的作用机理。实验结果表明,在U(Ⅵ)初始浓度为10 mg/L时,其最佳吸附pH值为3,去除率97.77%,吸附平衡时间120 min;吸附过程较好地拟合了准二级动力学模型(R2≈1)和Freundlich等温模型(R2≈1);X射线能谱和离子交换实验分析表明,离子交换为其主要吸附方式,参与交换的主要离子为Ca2+;红外光谱分析表明,PAS吸附U(Ⅵ)后自身结构未发生改变。以0.1 mol/L的HCl溶液作为解吸液,初次解吸率达92.83%,循环利用3次仍具有较好的吸附效果。

Adsorption characteristics of uranium by powdered activated sludge

The residual activated sludge from an urban sewage treatment plant was used to prepare powdered activated sludge (PAS) as a novel biological adsorbent. Different experimental parameters such as solution pH, adsorbent dose, initial concentration and contact time were examined to investigate their effects on adsorption of uranium by PAS. Changes of FT-IR spectra, scanning electron microscope and energy-dispersive spectrometry of PAS before and after adsorption were also studied. The results showed that the maximum adsorption occured at pH of 3, the adsorption reaches equilibrium within 120 min and the removal rate was up to 97.77% for initial U(Ⅵ) ions concentration of 10 mg/L. The equilibrium data fit well with the pseudo-second-order model(R2≈1) and Freundlich model(R2≈1). Ion exchange experiments and EDS analysis verified that ion exchange was the main adsorption mechanism with Ca2+ as the main exchange ion.FTIR spectra before and after PAS adsorbed uranium indicated that its structure did not change.The used PAS can be desorbed by 0.1 mol/L HCl(the first desorption rate is up to 92.83%) and became reusable. PAS is nontoxic and eco-friendly, which has a good prospect in the treatment of uranium-containing wastewater.