Anammox granular sludge bed technology has been widely applied for its attractive advantages. Efficient mass transfer is an important factor for the anammox granules to play their role. In this study, steady-state anammox granules were used to investigate the correlation between the permeability and granule size with the granule pore as pivot. The results of size distribution showed that the anammox granules could be divided into 6 groups: 200-500 μm (I), 500-1000 μm (II), 1000-1500 μm (III), 1500-2000 μm (IV), 2000-3000 μm (V) and ≥3000 μm (VI). The results of settling experiment demonstrated that the permeability of anammox granules was negatively correlated with the granule size. The fluid collection efficiency declined from 39.4% to 9.3% for granule group I to III, and further to 0 for granule group IV to VI (granule size was larger than 1.5 mm). The observation of micro-CT revealed that the pore structure of anammox granules varied significantly with the increase of granule size, forming a denser surface layer and sparser interior. The chemical analysis and microscopic observation indicated that the pore plugging of surface layer by cell proliferation and EPS secretion was the main cause for the permeability deterioration. The findings of this study will help to understand the mass transfer of anammox granules and promote the development of anammox processes.

Anammox颗粒污泥床技术因其吸引人的优势而被广泛应用。有效的传质是厌氧氨氧化颗粒发挥作用的重要因素。在这项研究中，稳态厌氧氨氧化颗粒被用来研究渗透率和颗粒大小之间的相关性，其中颗粒孔为支点。粒度分布结果表明，厌氧氨氧化颗粒可分为6组：200-500μm（I），500-1000μm（II），1000-1500μm（III），1500-2000μm（IV），2000 -3000μm（V）和≥3000μm（VI）。沉降实验结果表明，厌氧氨氧化颗粒的渗透性与颗粒大小呈负相关。颗粒组I至III的液体收集效率从39.4％降至9.3％，颗粒组IV至VI的液体收集效率进一步降至0（颗粒尺寸大于1。5毫米）。显微CT观察表明，厌氧氨纶颗粒的孔隙结构随着颗粒尺寸的增加而发生显着变化，形成了致密的表层和稀疏的内部。化学分析和显微镜观察表明，细胞增殖和EPS分泌导致表层孔隙堵塞是通透性下降的主要原因。这项研究的结果将有助于了解厌氧氨氧化颗粒的传质并促进厌氧氨氧化工艺的发展。化学分析和显微镜观察表明，细胞增殖和EPS分泌导致表层孔隙堵塞是通透性下降的主要原因。这项研究的结果将有助于了解厌氧氨氧化颗粒的传质并促进厌氧氨氧化工艺的发展。化学分析和显微镜观察表明，细胞增殖和EPS分泌导致表层孔隙堵塞是通透性下降的主要原因。这项研究的结果将有助于了解厌氧氨氧化颗粒的传质并促进厌氧氨氧化工艺的发展。