Saila Romana, Dhar Bipro Ranjan
Civil and Environmental Engineering, University of Alberta, 116 Street NW, Edmonton, AB T6G 1H9, Canada.
Civil and Environmental Engineering, University of Alberta, 116 Street NW, Edmonton, AB T6G 1H9, Canada.
Sci Total Environ. 2024 Dec 20;957:177589. doi: 10.1016/j.scitotenv.2024.177589. Epub 2024 Dec 2.
The increasing presence of nano and microplastics (NPs/MPs) in wastewater treatment plants and their inevitable accumulation in the sludge has raised serious concerns in recent years. This study investigated the effects of pristine and aged polyethylene microplastics (PEMPs), polystyrene nanoplastics (PsNPs), and their mixtures on the primary sludge fermentation process. Pristine MPs/NPs (150 μg/L and 2 g/L for PsNPs and PEMPs, respectively) underwent two weeks of weathering in the presence of humic and alginic acids. The results from a batch fermentation experiment (15 days, pH 10) revealed that the exposure to aged PEMPs/PsNPs experienced greater VFA production than pristine samples. Notably, the aged PEMPs/PsNPs mixture showed a 23.12% increase in VFA production over the pristine mixture. The relative abundance and total concentration of antibiotic resistance genes (ARGs) increased in all PEMPs/PsNPs batches compared to the control, with the most significant rise in total ARGs observed in the aged PEMPs sample. Aged PEMPs exhibited a 26.22-fold increase in tetA genes, while aged mix samples showed a 19.68-fold increase in tetM genes compared to their pristine counterparts. Both pristine and aged PEMPs/PsNPs, particularly the aged PEMPs adversely affected the microbial communities at the genus level and altered the microbial structure. Microbial richness and diversity were enhanced in samples exposed to pristine PEMPs/PsNPs and aged PsNPs but decreased in aged PEMPs and in the aged mixture group, suggesting a negative impact of aged polyethylene microplastics on microbial communities. Correlation analysis suggested that phyla Planctomycetes, Proteobacteria, and TM7 are potential hosts of ARGs. These findings manifest the substantial effects of aged nano/microplastics compared to their pristine forms, emphasizing the complex interplay between various forms of PEMPs/PsNPs and microbial dynamics in sludge fermentation processes.
近年来，纳米塑料和微塑料（NPs/MPs）在污水处理厂中日益增多，且不可避免地在污泥中积累，这引发了人们的严重担忧。本研究调查了原始态和老化态的聚乙烯微塑料（PEMPs）、聚苯乙烯纳米塑料（PsNPs）及其混合物对初沉污泥发酵过程的影响。原始态的 MPs/NPs（PsNPs 和 PEMPs 分别为 150 μg/L 和 2 g/L）在腐殖酸和海藻酸存在的情况下经历了两周的老化过程。批次发酵实验（15 天，pH 值为 10）的结果表明，与原始态样品相比，老化态的 PEMPs/PsNPs 产生的挥发性脂肪酸（VFA）更多。值得注意的是，老化态的 PEMPs/PsNPs 混合物的 VFA 产量比原始态混合物增加了 23.12%。与对照相比，所有 PEMPs/PsNPs 批次中抗生素抗性基因（ARGs）的相对丰度和总浓度均有所增加，其中老化态 PEMPs 样品中总 ARGs 的增加最为显著。与原始态相比，老化态 PEMPs 的 tetA 基因增加了 26.22 倍，而老化态混合样品的 tetM 基因增加了 19.68 倍。原始态和老化态的 PEMPs/PsNPs，特别是老化态的 PEMPs，在属水平上对微生物群落产生了不利影响，并改变了微生物结构。暴露于原始态 PEMPs/PsNPs 和老化态 PsNPs 的样品中微生物的丰富度和多样性有所增强，但在老化态 PEMPs 和老化态混合组中则有所下降，这表明老化态聚乙烯微塑料对微生物群落有负面影响。相关性分析表明，浮霉菌门、变形菌门和 TM7 是 ARGs 的潜在宿主。这些发现表明，与原始形态相比，老化态的纳米/微塑料具有显著影响，强调了不同形式的 PEMPs/PsNPs 与污泥发酵过程中微生物动态之间的复杂相互作用。
