Sha Wu, Yijie Quan, Fei Gao, Lixiu Shi, Zhihua Liu, Eli Hendrik Sanjaya, Mohd Fadhil Bin Md Din, Hong Chen
Graphene oxide (GO) sponges have emerged as promising functional materials in bioengineered wastewater treatment systems; however, their influence on microbial ecology and environmental sustainability in single-stage partial nitritation–Anammox (PN/A) processes remains insufficiently understood. This study explores whether GO sponge amendment can facilitate autotrophic nitrogen removal in a novel airlift inner-circulation partition bioreactor (AIPBR). Following the addition of GO sponges, the reactor exhibited an increase in average nitrogen removal rate (NRR) from 0.57 to 0.68 kg N/m3-d under steady-state. Specific activity tests indicated enhanced activities of ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing bacteria (AnAOB), accompanied by increased relative abundances of Nitrosomonas , Candidatus Brocadia , and Candidatus Jettenia . In this study, GO sponges were observed to act as macroporous scaffolds that promoted biomass retention and microbial co-localization, while inducing the secretion of tightly bound protein-rich EPS, which may alleviate electrochemical stress associated with GO surface conductivity. In addition, GO amendment was associated with shifts in nitrogen transformation-related genes, indicating potential modulation of electron transfer pathways. Notably, the near-complete loss of nosZ and the emergence of norB may imply a metabolic shift toward N₂O accumulation. These findings suggest that GO sponges may influence PN/A performance by shaping microbial ecology and interfacial interactions, while highlighting the need to further assess associated environmental trade-offs. © 2026 Elsevier Ltd.
School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha, 410114, China; School of Hydraulic and Ocean Engineering, Changsha University of Science & Technology, Changsha, 410114, China; Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, Changsha, 410114, China; Chemistry Department, Universitas Negeri Malang, 65145, Indonesia; Centre for Environmental Sustainability and Water Security (IPASA), School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Johor, Skudai, 81310, Malaysia
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