Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Campus Puebla, Reserva Territorial Atlixcáyotl, Puebla, Pue, CP 72453, Mexico; Department of Civil and Environmental Engineering, Engineering Division, University of Guanajuato, Av. Juárez 77, Zona Centro, Guanajuato, Gto, 36000, Mexico.
Department of Civil and Environmental Engineering, Engineering Division, University of Guanajuato, Av. Juárez 77, Zona Centro, Guanajuato, Gto, 36000, Mexico.
J Environ Manage. 2021 Jan 1;277:111428. doi: 10.1016/j.jenvman.2020.111428. Epub 2020 Oct 6.
Titanium dioxide nanoparticles (TiO NPs) are widely used in consumer products and one of their major fate is the wastewater treatment plants. However, NPs eventually arrive to aquatic and terrestrial ecosystems via treated water and biosolids, respectively. Since low concentration of NPs is accumulating in the upflow anaerobic sludge blanket (UASB) reactors that treat wastewater and reclaim water quality, the accumulation of TiO NPs in these reactors may impact in their performance. In this work, the long-term effects of TiO NPs on the main benefits of treating wastewater by UASB reactors such as, biogas production, methane fraction in biogas and organic matter removal were evaluated. Evaluation consisted of monitoring such parameters in two identical UASB reactors, one UASB-Control (without NPs) and the experimental one (UASB-TiO NPs) that received wastewater with TiO NPs. The fate of NPs in the UASB reactor was also determined. Results indicated that biogas production increased by 8.8% due to the chronic exposure of UASB reactor to TiO NPs during the first 44 days of experiment. However, the methane content in the biogas had no significant differences between both UASB, ranging between 78% and 90% of methane during the experiment. The removal of organic matter in both UASB was similar and ranged 92-98% along the experimental time. This means that accumulation of TiO NPs did not altered the biogas production and organic matter removal. However, the content of total volatile solids (TVS) in UASB-TiO NPs dropped off from 137.8 g to 64.2 g in 84 days, while for control reactor that decreased from 141.6 g to 92.4 g in the same period. Hence, the increased biogas production in the UASB exposed to TiO was attributed to hydrolysis of the TVS in this reactor. The main fate of TiO NPs was the granular sludge, which accumulated up to 8.56 mg Ti/g, which represent around 99% of the Ti spiked to the reactor and the possible cause of the biomass hydrolyzation in the UASB. Disposal of UASB sludge containing NPs from may raise ecotoxicological concerns due to the use of biosolids in agricultural activities.
二氧化钛纳米粒子（TiO NPs）广泛应用于消费产品，其主要命运之一是进入废水处理厂。然而，纳米颗粒最终分别通过处理过的水和生物固体进入水生和陆地生态系统。由于低浓度的纳米颗粒在处理废水和回收水质的上流式厌氧污泥床（UASB）反应器中积累，因此这些反应器中 TiO NPs 的积累可能会影响其性能。在这项工作中，评估了 TiO NPs 对 UASB 反应器处理废水的主要益处（如沼气产量、沼气中的甲烷比例和有机物去除）的长期影响。评估包括在两个相同的 UASB 反应器中监测这些参数，一个 UASB 对照（无 NPs）和一个实验用的 UASB-TiO NPs，该反应器接收含有 TiO NPs 的废水。还确定了 NPs 在 UASB 反应器中的命运。结果表明，由于 UASB 反应器在实验的前 44 天内受到 TiO NPs 的慢性暴露，沼气产量增加了 8.8%。然而，在整个实验过程中，沼气中的甲烷含量在两个 UASB 之间没有显著差异，甲烷含量在 78%至 90%之间。两个 UASB 的有机物去除率相似，在整个实验过程中范围为 92-98%。这意味着 TiO NPs 的积累并没有改变沼气产量和有机物去除率。然而，在 84 天内，UASB-TiO NPs 中的总挥发性固体（TVS）含量从 137.8 g 下降到 64.2 g，而对照反应器在同一时期从 141.6 g 下降到 92.4 g。因此，暴露于 TiO 的 UASB 中增加的沼气产量归因于该反应器中 TVS 的水解。TiO NPs 的主要归宿是颗粒污泥，其积累量高达 8.56 mg Ti/g，这代表了注入反应器的 Ti 的 99%左右，也是 UASB 中生物质水解的可能原因。由于在农业活动中使用生物固体，从含有 NPs 的 UASB 污泥中处置可能会引起生态毒理学问题。
