氧氟沙星与聚苯乙烯微塑料复合污染对剩余污泥厌氧消化的影响

Effects of combined ofloxacin and polystyrene microplastics on anaerobic digestion of waste activated sludge

为探究抗生素与微塑料复合污染对厌氧消化的作用影响,采用BMP实验考察了不同质量浓度氧氟沙星(OFL)、聚苯乙烯(PS)微塑料对剩余污泥厌氧消化产甲烷的影响行为,并通过分析溶解性有机物(DOM)、胞外聚合物(EPS)变化规律、厌氧发酵4阶段代谢以及微生物群落探讨其影响机理。结果表明,与对照组相比,单一OFL和单一PS微塑料污染使甲烷累积产量分别下降了15.95%~81.36%、4.25%~5.78%;而在复合条件下,两者表现出协同效应,故导致产甲烷速率的进一步下降和有效产气时间的缩短,其中OFL胁迫占主导。机理探究发现,不论单一OFL还是复合污染,DOM中腐殖质类物质均明显增加,EPS组分结构趋于复杂化,厌氧消化4阶段均受到明显抑制。单一PS微塑料污染在反应初期可提高产甲烷速率,且对厌氧消化4阶段的影响相对较小。微生物群落分析发现,复合组与单一OFL组群落分布更为相近,产酸细菌与嗜乙酸产甲烷菌的相对丰度均明显下降,这导致乙酸营养型产甲烷途径受到严重抑制。本研究结果可为复杂污染情况下剩余污泥资源化处理的工艺调控提供参考。

In order to explore the influence of combined antibiotic and microplastic on anaerobic digestion, the effects of two pollutants, ofloxacin(OFL) and polystyrene(PS) microplastics, on anaerobic digestion were investigated at different mass concentrations by BMP tests. The mechanism was explored by analyzing dissolved organic matter(DOM), extracellular polymeric substance(EPS), four stages metabolic process of anaerobic digestion and microbial community. The results showed that the individual OFL and individual PS microplastics decreased the methane cumulative production by 15.95%~81.36% and 4.25%~5.78%,respectively, compared to the control. However, under the combined conditions, the two showed synergistic effects, leading to the further decrease in methane production rate and the reduction in effective gas production time, in which OFL stress was dominant. The mechanism analysis revealed that both individual OFL pollution and combined pollution greatly increased the humic substances in DOM, complicated the structure of EPS components and inhibited the efficiency of the four stages of anaerobic digestion. The individual PS microplastics pollution increased methane production rate at the beginning of the reaction, and caused relatively less effect on the four stages. Microbial community analysis indicated that the combined pollution had a more similar community distribution to the individual OFL pollution. The relative abundance of acidification bacteria and acetic acid methanogen decreased significantly, which resulted in a severe suppression of methanogenic pathway of acetic acid nutrition. The results of this study can provide a reference for the process regulation of waste sludge resource treatment under complex pollution situations.