Unraveling the resistance mechanism of anammox granular sludge to iron nanoparticles

Xun Weng; Meng-Jiao Gao; Zheng Mao; Hui-Min Fu; Shi-Jun Li; Peng Yan; You-Peng Chen

doi:10.1016/j.jenvman.2024.123565

Unraveling the resistance mechanism of anammox granular sludge to iron nanoparticles

J Environ Manage. 2024 Dec 3:373:123565. doi: 10.1016/j.jenvman.2024.123565. Online ahead of print.

Authors

Xun Weng¹, Meng-Jiao Gao¹, Zheng Mao², Hui-Min Fu³, Shi-Jun Li¹, Peng Yan¹, You-Peng Chen⁴

Affiliations

¹ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing, 400045, China.
² Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing, 400045, China; Chongqing Institute of Geology and Mineral Resources, Chongqing, 401120, China.
³ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing, 400045, China; National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing, 400067, China.
⁴ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing, 400045, China. Electronic address: ypchen@cqu.edu.cn.

PMID: 39632309
DOI: 10.1016/j.jenvman.2024.123565

Abstract

Iron nanoparticles (FeNPs) generated from industrial activities could end up into the sewer system, and potentially affect wastewater treatment processes. The impact of FeNPs on anammox process is getting increasing attention. However, the resistance mechanism of anammox granular sludge (AnGS) to FeNPs has not been fully elucidated. The current study investigated the metabolic and morphological response of AnGS to acute and chronic FeNPs exposure. Results showed that nitrogen removal efficiencies were elevated at 1-4 mM FeNPs concentrations compared to 0-0.5 mM FeNPs. Extracellular protein and tyrosine-like and tryptophan-like fluorophore secretions of AnGS were stimulated by FeNPs, which largely contributed to the adsorption of FeNPs on AnGS surface. FeNPs exposure triggered higher necrotic fraction of AnGS compared with no FeNPs condition. Highly absorbed particles appeared inside the bacterial cells of AnGS, soft X-ray imaging illustrated that anammox bacteria maintained intact cellular and anammoxosome structures whereas non-anammox bacterial structures were damaged under FeNPs exposure. Anammox bacterial abundance increased from 4.84% to 20.64%, when FeNPs concentrations increased from 0 mM to 4 mM, and anammoxosome membrane ensured anammox bacterial metabolism under FeNPs exposure. This study extended fundamental understanding of AnGS resistance mechanisms to FeNPs.

Keywords: Anaerobic ammonia oxidation (anammox); Extracellular polymeric substances (EPS); Iron nanoparticles (FeNPs); Micromorphology.