摘要

    厌氧消化是稳定废水处理厂（WWTPs）中生物固体的主要方法，可以有效地大大减弱生物污泥中的抗生素抗性。这项研究的目的是研究超声辐照结合臭氧（US / O3）进行氧化预处理对带有微量氟喹诺酮类污染物左氧氟沙星（LEVO）的生物污泥的中温和嗜热厌氧消化（MAD和TAD）的影响。最近几年。在氧化过程中，痕量LEVO几乎完全降解。 US / O3预处理的TAD剂量为0.1 mg / L LEVO的产甲烷活性大大高于单个MAD和TAD的产甲烷活性，因此导致沼气产量显着增加。利用LCMS技术对左氧氟沙星中间体的化学降解进行了鉴定，提出了基于左氧氟沙星中间体的反应途径。 US / O3提供的羟基自由基导致LEVO的氧化开环以及生物污泥中其他生物大分子的降解。此外，在US / O3预处理的TAD中，喹啉抗性基因qnrA和qnrS显着下降了1-2个数量级，表明US / O3产生的活性基团氧化并降解了LEVO，从而使抗生素抗性细菌或基因失活。在生物固体中。同时，微生物群落的组成和结构发生了变化，总细菌和潜在人类病原体的多样性和丰富度下降，其模式与抗LEVO基因相关。在与AD相关的著名门生动物中，包括拟杆菌，硬毛菌，甲烷菌以及之前在TAD中检测到并进行有机水解和降解的嗜热菌，潜在的耐LEVO细菌可能与放线菌，拟杆菌，变形杆菌，嗜热菌有关。 。这项研究揭示了US / O3预处理对减少LEVO暴露的生物污泥的ARGs减少对厌氧消化的贡献，并可以为控制ARB和ARGs在污水污泥中的扩散提供有用的指导。

    Anaerobic digestion, the principal method of stabilizing biosolids in wastewater treatment plants (WWTPs), can efficiently and largely attenuate the antibiotic resistances in biosludge. This study aims to investigate the effect of oxidative pretreatment with ultrasound irradiation combined with ozone (US/O3) on the mesophilic and thermophilic anaerobic digestion (MAD and TAD) for the biosludge bearing trace fluoroquinolones contaminants-levofloxacin (LEVO) which was widely used in recent years. During the oxidation, the trace-level LEVO was almost completely degraded. The methanogenic activity in US/O3 pretreated TAD dosed 0.1 mg/L LEVO was much higher than those in single MAD and TAD, therefore leading to a remarkable increase in biogas production. The identification of levofloxacin intermediates during chemical degradation was analyzed using LCMS technique and the reaction pathway based on them was proposed. Hydroxyl radicals provided by US/O3 contributed to oxidative ring opening of LEVO as well as degradation of other biomacromolecules in the biosludge. Besides, the quinoline resistance genes-qnrA and qnrS declined significantly by 1–2 orders of magnitude in US/O3-pretreated TAD, indicating that the active radicals produced by US/O3 oxidized and degraded LEVO and therefore inactivated the antibiotic resistant bacteria or genes in the biosolids. Meanwhile, the composition and structure of the microbial community altered and the diversity and richness of total bacterial and potential human pathogens decreased, the pattern of which was correlated with LEVO-resistant genes. Among the well-known AD-related phylum including Bacteroidetes, Firmicutes, Methanobacteria as well as Thermotogae which has been previously detected in TAD and performed organic hydrolysis and degradation, the potential LEVO-resistant bacteria were probably affiliated to Actinobacteria, Bacteroidetes, Proteobacteria, Thermotogae. This study revealed the contribution of US/O3 pretreatment to the anaerobic digestion in terms of ARGs reduction for trace-LEVO- exposed biosludge and could provide useful guidance for controlling the dissemination of ARB and ARGs in sewage sludge.

    https://www.sciencedirect.com/science/article/pii/S0301479720302917