Previous studies mostly focused on the responses of anaerobic granular sludge (AGS) to one kind of microplastics during wastewater treatment. However, a wide variety of microplastics has been detected in wastewater. The multiple microplastics induced stress on AGS and the effectively mitigating strategy still remain unavailable. Herein, this work comprehensively excavated the influences of multiple microplastics (i.e., polyethylene terephthalate (PET), polystyrene (PS), polyethylene (PE) and polypropylene (PP)) coexisting in the wastewater on AGS system from macroscopic to microcosmic aspects. Experimental results illustrated that microplastics decreased AGS granule size, increased cell inactivation and caused deteriorative methane recovery from wastewater. As such, this study then put great emphasis on proposing a mitigating strategy using hydrochar and disclosing the role of hydrochar in overcoming the stress induced by coexisting microplastics to AGS system. Physiological characterization and microbial community analysis demonstrated that hydrochar effectively mitigated the reductions in methane production by 50.6% and cell viability by 68.8% of microplastics-bearing AGS and reduced the toxicity of microplastics to microbial community in the AGS. Mechanisms investigation by fluorescence tagging and excitation emission matrix fluorescence spectroscopy with fluorescence regional integration (EEM-FRI) analysis revealed that hydrochar adsorbed/accumulated microplastics and enhanced microplastics-bearing AGS to secrete extracellular polymeric substance (EPS) with more humic acid generation, thus reducing the direct contact between microplastics and AGS. In addition, hydrochar weakened the AGS intracellular oxidative stress induced by microplastics, thereby completely eliminating the inhibition of microplastics on acidification efficiency of AGS, and partially mitigating the suppression on methanation.

以前的研究主要集中在厌氧颗粒污泥（AGS）在废水处理过程中对一种微塑料的响应。然而，已在废水中检测到多种微塑料。多种微塑料在 AGS 上引起的压力和有效的缓解策略仍然不可用。在此，本工作全面挖掘了多种微塑料（即聚对苯二甲酸乙二醇酯（PET）、聚苯乙烯（PS）、聚乙烯（PE）和聚丙烯（PP）共存于AGS系统废水中，从宏观到微观。实验结果表明，微塑料降低了 AGS 颗粒尺寸，增加了细胞失活，并导致废水中甲烷回收率下降。因此，本研究随后重点提出了一种使用水炭的缓解策略，并揭示了水炭在克服共存微塑料对 AGS 系统引起的应力方面的作用。生理表征和微生物群落分析表明，水炭有效地减缓了 50.6% 的甲烷产量减少和 68.8% 的微塑料承载 AGS 的细胞活力，并降低了微塑料对 AGS 中微生物群落的毒性。通过荧光标记和激发发射矩阵荧光光谱与荧光区域积分（EEM-FRI）分析的机制研究表明，水炭吸附/积累微塑料并增强携带微塑料的 AGS 分泌具有更多腐植酸生成的细胞外聚合物（EPS），从而减少微塑料和AGS之间的直接接触。此外，水炭减弱了微塑料诱导的AGS细胞内氧化应激，从而完全消除了微塑料对AGS酸化效率的抑制作用，部分减轻了对甲烷化的抑制作用。