CEB, Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal.
Laboratory of Separation and Reaction Engineering, Laboratory of Catalysis and Materials (LSRE-LCM), Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal.
Int J Mol Sci. 2021 Mar 13;22(6):2932. doi: 10.3390/ijms22062932.
In anaerobic bioreactors, the electrons produced during the oxidation of organic matter can potentially be used for the biological reduction of pharmaceuticals in wastewaters. Common electron transfer limitations benefit from the acceleration of reactions through utilization of redox mediators (RM). This work explores the potential of carbon nanomaterials (CNM) as RM on the anaerobic removal of ciprofloxacin (CIP). Pristine and tailored carbon nanotubes (CNT) were first tested for chemical reduction of CIP, and pristine CNT was found as the best material, so it was further utilized in biological anaerobic assays with anaerobic granular sludge (GS). In addition, magnetic CNT were prepared and also tested in biological assays, as they are easier to be recovered and reused. In biological tests with CNM, approximately 99% CIP removal was achieved, and the reaction rates increased ≈1.5-fold relatively to the control without CNM. In these experiments, CIP adsorption onto GS and CNM was above 90%. Despite, after applying three successive cycles of CIP addition, the catalytic properties of magnetic CNT were maintained while adsorption decreased to 29 ± 3.2%, as the result of CNM overload by CIP. The results suggest the combined occurrence of different mechanisms for CIP removal: adsorption on GS and/or CNM, and biological reduction or oxidation, which can be accelerated by the presence of CNM. After biological treatment with CNM, toxicity towards was evaluated, resulting in ≈ 46% detoxification of CIP solution, showing the advantages of combining biological treatment with CNM for CIP removal.
在厌氧生物反应器中，有机物氧化过程中产生的电子可用于废水生物还原。常见的电子传递限制通过利用氧化还原介体（RM）来加速反应得到改善。这项工作探索了碳纳米材料（CNM）作为 RM 对环丙沙星（CIP）厌氧去除的潜力。首先测试了原始和定制化的碳纳米管（CNT）对 CIP 的化学还原作用，发现原始 CNT 是最佳材料，因此进一步将其与厌氧颗粒污泥（GS）用于生物厌氧测定。此外，制备了磁性 CNT 并在生物测定中进行了测试，因为它们更容易回收和重复使用。在含有 CNM 的生物测试中，CIP 的去除率达到了约 99%，与不含有 CNM 的对照相比，反应速率提高了约 1.5 倍。在这些实验中，CIP 对 GS 和 CNM 的吸附率均高于 90%。尽管如此，在经过三次连续添加 CIP 的循环后，磁性 CNT 的催化性能仍然得以维持，而吸附率下降至 29±3.2%，这是由于 CIP 对 CNM 的过载。结果表明，CIP 去除的同时发生了不同的机制：在 GS 和/或 CNM 上的吸附以及生物还原或氧化，而 CNM 的存在可以加速这些过程。用 CNM 进行生物处理后，评估了对 的毒性，结果表明 CIP 溶液的解毒率约为 46%，这表明将生物处理与 CNM 结合用于 CIP 去除具有优势。
