State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia.
Water Res. 2022 Jul 15;220:118607. doi: 10.1016/j.watres.2022.118607. Epub 2022 May 16.
Recent investigations confirmed the inhibitory effect of microplastics with single sizes on the anaerobic granular sludge (AGS) wastewater treatment system. However, the differences of toxicity from different sizes of microplastics toward AGS and their underlying mechanism are still unclear. In this work, the responds of AGS exposed to different particle sizes of polystyrene microplastics (PS-MPs) were reported. The results showed that the increasing particle sizes (from 0.5 μm to 150 μm) of PS-MPs induced a gradually increasing and distinct inhibitory (from 6.7% to 16.2%) effect on the cumulative methane production by AGS, accompanied by the similar decreasing organic carbon degradation trends. Correspondingly, the integrity and the cell viability of the AGS granules were damaged and the populations of the key acidogens and methanogens were reduced when exposed to PS-MPs, which was particularly evident in the reactors affected by the larger micron-sized PS-MPs. The zeta potential and contact angle indicated that the larger-sized PS-MPs had the stronger dispersive properties and affinity for AGS, causing the higher oxidative stress and leachates toxicity. Further investigation revealed that the tolerance of AGS to PS-MPs toxicity also exhibited size-dependent trend. Larger particles (e.g., 150 μm) of PS-MPs inhibited extracellular polymeric substance (EPS) secretion, while smaller particles (e.g., 0.5 μm) promoted EPS generation with the release of more humic acid, alleviating their toxicity.
最近的研究证实了单一尺寸的微塑料对厌氧颗粒污泥（AGS）废水处理系统的抑制作用。然而，不同尺寸的微塑料对 AGS 的毒性差异及其潜在机制仍不清楚。在这项工作中，报道了AGS 暴露于不同粒径聚苯乙烯微塑料（PS-MPs）的响应。结果表明，PS-MPs 的粒径（从 0.5μm 增加到 150μm）逐渐增加，对 AGS 累积甲烷生成的抑制作用也明显增强（从 6.7%增加到 16.2%），同时有机碳降解趋势也相似。相应地，AGS 颗粒的完整性和细胞活力受到破坏，关键产酸菌和产甲烷菌的数量减少，当暴露于 PS-MPs 时，这种情况在受较大微米级 PS-MPs 影响的反应器中尤为明显。zeta 电位和接触角表明，较大粒径的 PS-MPs 具有更强的分散性和与 AGS 的亲和力，导致更高的氧化应激和浸出毒性。进一步的研究表明，AGS 对 PS-MPs 毒性的耐受性也表现出尺寸依赖性趋势。较大的颗粒（例如 150μm）抑制了细胞外聚合物（EPS）的分泌，而较小的颗粒（例如 0.5μm）促进了 EPS 的生成，并释放了更多的腐殖酸，从而减轻了其毒性。
