Abstract:

Aerobic granular sludge(AGS), characterized by high biological retention capacity and environmental stress resistance, has emerged as a frontier technology for dyeing wastewater treatment. However, the impact of cellulosic fibre microplastics(CFMPs), a typical contaminant in the dyeing industry, on the pollutant removal efficiency of AGS and the underlying mechanisms remain unclear. This study systematically investigated the gradient effects of CFMPs at 0-50 mg/L on AGS for the first time, revealing differential mechanisms based on the interaction between extracellular polymeric substances(EPS) and microbial communities. The results showed that the effect of CFMPs on AGS was concentration-dependent: the system remained stable with no significant change in pollutant removal efficiency at ≤5 mg/L. When the concentration exceeded 20 mg/L, AGS exhibited decreased removal capacities for chemical oxygen demand(COD), total nitrogen(TN), and total phosphorus(TP), with removal rates dropping to 81.6%,60.6%, and 81.3% respectively at 50 mg/L. Mechanistic analysis indicated that high-concentration CFMPs induced defensive stress in AGS through physical interference, leading to 32%-58% increase in EPS content compared to the control group. The imbalance between protein(PN) and polysaccharide(PS) in EPS exacerbated granular structure loosening. Meanwhile, the microbial community structure was significantly reconstructed, with reduced abundances of functional bacteria such as Proteobacteria and Bacteroidota, directly hindering metabolic pathways. This study for the first time confirmed the “low-concentration compatibility-high-concentration antagonism” effect of CFMPs on AGS,provided concentration control thresholds and microbial regulation strategies for the treatment of dyeing wastewater containing CFMPs, and improves the theoretical system of microplastic pollution control.

Key words: aerobic granular sludge, cellulosic fibre microplastics, dyeing wastewater, extracellular polymeric substances, microbial community structure

摘要：

好氧颗粒污泥（AGS）因具有高效生物截留与环境抗逆性，成为印染废水处理前沿技术。然而，印染行业典型污染物化纤类微塑料（CFMPs）对AGS污染物去除效能的影响及机制尚不明确。首次系统探究0~50 mg/L CFMPs对AGS的梯度效应，揭示基于胞外聚合物（EPS）-微生物菌群相互作用的差异化机制。结果表明，CFMPs对AGS的作用呈浓度依赖性：CFMPs≤5 mg/L时系统稳定，污染物去除无显著变化；CFMPs>20 mg/L时，AGS对化学需氧量（COD）、总氮（TN）、总磷（TP）的去除能力开始衰减，CFMPs为50 mg/L时去除率分别降至81.6%、60.6%、81.3%。机制显示，高浓度CFMPs通过物理干扰引发AGS防御性应激，导致EPS较对照组增加32%~58%，蛋白质（PN）与多糖（PS）比例失衡加剧颗粒结构松散；同时，微生物群落中变形菌门（Proteobacteria）和拟杆菌门（Bacteroidota）等功能菌丰度下降，代谢通路受阻。首次证实CFMPs对AGS的“低浓度相容-高浓度拮抗”效应，为含CFMPs印染废水处理提供了浓度控制阈值与微生物调控策略，完善了微塑料污染控制理论。

关键词: 好氧颗粒污泥, 化纤类微塑料, 印染废水, 胞外聚合物, 微生物菌群结构

CLC Number: 

• X703.1