Optimizing granules size distribution is critical for both reactor performance and stability. In this research, an optimal size range of 1800 to 3000 μm was proposed regarding mass transfer and granules stability based on granules developed at DO around 8.0 mg L⁻¹ with the feed COD:N:P at 100:5:1. A height-adjustable influent strategy was applied to facilitate the nutrient storage of granules at optimum size range via microbial selective pressure. Results suggested insufficient hydraulic shear stress led to overgrowth of granules size. High abundance of filamentous bacteria (Thiothrix sp.) was observed in oversized granules, which detached and affected the remaining granules, resulting in severe sludge bulking. Strong hydraulic shear stress suppressed uncontrolled growth of granules. However, fewer abundance of simultaneous nitrification and denitrification (SND) bacterium was acquired, which led to unfavored SND effect and total nitrogen (TN) removal efficiency. The height-adjustable influent strategy facilitated the poly-β-hydroxybutyrate (PHB) storage of granules at optimum size range, while limiting the overgrowth of granules size. Additionally, more than 87.51% of total granules situated in optimal sizes range, which led to higher abundance of SND bacterium and higher TN removal efficiency.

优化颗粒尺寸分布对反应器性能和稳定性都至关重要。在这项研究中，基于在 DO 约 8.0 mg L ^-1和进料 COD:N:P 为 100:5:1 下开发的颗粒，提出了 1800 至 3000 μm 的最佳尺寸范围，以考虑传质和颗粒稳定性。应用高度可调的进水策略，通过微生物选择压力促进颗粒在最佳尺寸范围内的营养储存。结果表明水力剪切应力不足导致颗粒尺寸过度生长。高丰度的丝状细菌（Thiothrixsp.) 在超大颗粒中观察到，它分离并影响剩余的颗粒，导致严重的污泥膨胀。强大的水力剪切应力抑制了颗粒不受控制的生长。然而，同时硝化和反硝化 (SND) 细菌的丰度较少，这导致不利的 SND 效应和总氮 (TN) 去除效率。高度可调的进水策略促进了颗粒在最佳尺寸范围内的聚-β-羟基丁酸酯 (PHB) 储存，同时限制了颗粒尺寸的过度生长。此外，超过 87.51% 的总颗粒位于最佳尺寸范围内，这导致更高的 SND 细菌丰度和更高的 TN 去除效率。