Department of Civil Engineering & Environmental Engineering, Engineering Division, University of Guanajuato, Av. Juárez 77, Guanajuato, Gto., CP 36000, Mexico.
Department of Civil Engineering & Environmental Engineering, Engineering Division, University of Guanajuato, Av. Juárez 77, Guanajuato, Gto., CP 36000, Mexico.
Chemosphere. 2017 Sep;182:672-680. doi: 10.1016/j.chemosphere.2017.05.074. Epub 2017 May 16.
The aim of this work was to evaluate the impact generated by ZnO NPs on the activated sludge process treating raw (RWW) and filtered wastewater (FWW). It was analyzed the oxygen uptake rate, nutrient removal, flocs characteristics and the morphological interactions between activated sludge and ZnO NPs, in presence of 450-2000 mg/L. The results showed that the presence of more than 450 mg/L of ZnO NPs in raw and filtered wastewater inhibited the oxygen uptake by activated sludge. The highest inhibition was 35% in presence of 1500 mg/L in RWW. The organic matter removal was only inhibited in the presence of 450 and 900 mg/L of ZnO NPs; while ammonia removal decreased for all concentrations of ZnO NPs in both types of wastewater, around 13% for RWW and up to 9% for FWW. The orthophosphate removal improved as the concentration of ZnO NPs increased for both wastewater types, enhancing up to 8% for RWW and 17% for FWW. The flocs size of activated sludge exposed to ZnO NPs in RWW decreased as the concentration of ZnO NPs increased; while for FWW, an opposite effect was observed. The elemental mapping allowed detect the Zn inside of microorganisms, which may correspond to a toxicity mechanism in RWW and FWW. These results indicated that the changes in nutrient removal and flocs characteristics caused by the presence of ZnO NPs on the activated sludge are related to wastewater characteristics, such as suspended solids, type of substrate and concentration of ZnO NPs.
本工作旨在评估 ZnO NPs 对处理原水（RWW）和过滤废水（FWW）的活性污泥工艺的影响。分析了在 450-2000 mg/L 存在下，好氧速率、营养物去除、絮体特性以及活性污泥与 ZnO NPs 之间的形态相互作用。结果表明，RWW 和 FWW 中存在超过 450 mg/L 的 ZnO NPs 会抑制活性污泥的耗氧。在 RWW 中存在 1500 mg/L 时，抑制作用最高达到 35%。有机物去除仅在存在 450 和 900 mg/L ZnO NPs 时受到抑制；而在两种废水中，所有 ZnO NPs 浓度下氨氮去除率均降低，RWW 约为 13%，FWW 高达 9%。对于两种废水类型，随着 ZnO NPs 浓度的增加，正磷酸盐去除率均有所提高，RWW 提高了 8%，FWW 提高了 17%。暴露于 RWW 中 ZnO NPs 的活性污泥的絮体大小随着 ZnO NPs 浓度的增加而减小；而对于 FWW，则观察到相反的效果。元素映射允许检测到微生物内部的 Zn，这可能对应于 RWW 和 FWW 中的毒性机制。这些结果表明，由于 ZnO NPs 的存在对活性污泥造成的营养物去除和絮体特性的变化与废水特性有关，例如悬浮固体、基质类型和 ZnO NPs 的浓度。
