Jiakai Hu, Ronghua Xu, Jingyi Jiang, Muhammad Rizwan, Mohd Fadhil Md Din, Elsayed Ali Elsayed Ali, Eli Hendrik Sanjaya, AbdelGawad Saad, Zhe Kong, Hong Chen
Long-term performance degradation mechanisms and media-specific dynamics in field-scale roof-runoff bioretention remain poorly understood. Consequently, this study, initiated after three years of long-term operation, focused on the continued monitoring of a volcanic rock-based assembled bioretention facility (ABF-V) and a zeolite-based assembled bioretention facility (ABF-Z). ABF-Z demonstrated superior removal efficiencies for total phosphorus (TP, 68.48 ± 39.17 %), ammonium nitrogen (NH₄⁺-N, 83.75 ± 21.76 %), and suspended solids (SS, 76.97 ± 18.65 %), whereas ABF-V achieved higher chemical oxygen demand (COD, 50.58 ± 32.33 %) removal. Despite a modest decline in overall performance, high hydraulic loading events caused significant fluctuation in removal efficiency and intermittent pollutant leaching. Notably, ABF-V exhibited progressive instability, eroding its initial advantage and allowing ABF-Z to surpass it. Subsequent analyses of microbial community composition and media physicochemical properties further elucidated the cause of the observed performance reversal. Specifically, ABF-Z exhibited higher microbial diversity and abundance and was markedly enriched with taxa associated with nitrogen cycling (e.g., Proteobacteria and Xanthobacteraceae ). Furthermore, the microporous structure of zeolite provided high NH₄⁺-N adsorption capacity (70.56 % within 2 h), while its high silica content (68.3 % SiO2) enhanced long-term structural stability. These findings indicate that prolonged operation shifts the treatment dominance from initial media adsorption to microbial transformation, emphasizing the necessity of stable media that promote microbial synergy to mitigate long-term decline. Therefore, the strategic employment of zeolite in bioretention systems ensures long-term runoff pollution control and microbial ecosystem stability. © 2026 Elsevier Ltd.
School of Hydraulic and Ocean Engineering, Changsha University of Science and Technology, Changsha, 410114, China; School of Civil and Environmental Engineering, Changsha University of Science and Technology, Changsha, 410114, China; Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, Changsha, 410114, China; Department of Environmental Engineering, Faculty of Civil Engineering, Universiti Teknologi Malaysia, Johor, Skudai, 81310, Malaysia; Agricultural Engineering Research Institute (AEnRI), Agricultural Research Center (ARC), 12311, Egypt; Department of Chemistry, State University of Malang (Universitas Negeri Malang), Jl. Semarang No. 5, East Java, Malang, 65145, Indonesia; Suzhou National Joint Laboratory of Green and Low-carbon Wastewater Treatment and Resource Utilization, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China
