Exploring the Effects of Different Fillers on the Treatment of Wastewater by SBBR System: Denitrification Efficiency and Microbial Community - Shuli Liu; Xiaohong Han; Miao Zhou; Yatong Gao; Yuhong Zhang; Qi Li; Ning Guo; Jiajun Hua; Jia Kang; Gangfu Song (Water, Air, & Soil Pollution, 2025)