A novel micromagnetic carrier-modified integrated fixed-film activated sludge system for simultaneous efficient removal of tetracycline and mitigation of antibiotic resistance genes proliferation and dissemination

Yuan-Mo Zhu; Yi Xue; Kai Jin; Yongsheng Chen; Hongqiang Ren; Ke Xu

doi:10.1016/j.watres.2025.123166

A novel micromagnetic carrier-modified integrated fixed-film activated sludge system for simultaneous efficient removal of tetracycline and mitigation of antibiotic resistance genes proliferation and dissemination

Water Res. 2025 Jan 20:274:123166. doi: 10.1016/j.watres.2025.123166. Online ahead of print.

Authors

Yuan-Mo Zhu¹, Yi Xue¹, Kai Jin², Yongsheng Chen¹, Hongqiang Ren¹, Ke Xu³

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing, Jiangsu 210023, China.
² Nanjing University Yixing Environmental Protection Research Institute, Yixing, Jiangsu 214200, China.
³ State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing, Jiangsu 210023, China. Electronic address: kexu@nju.edu.cn.

PMID: 39854780
DOI: 10.1016/j.watres.2025.123166

Abstract

To address the challenge of antibiotic-containing wastewater, a novel micromagnetic carrier-modified integrated fixed-film activated sludge system (MC-IFAS) was developed for treating tetracycline (TC)-containing swine wastewater in this study. The magnetic effects of the MC significantly enhanced TC removal by improving TC biosorption and biodegradation in both the suspended activated sludge and the carrier-attached biofilm in the MC-IFAS. The increased electrostatic attraction and number of binding sites in both the activated sludge and the biofilm enhanced their TC biosorption capacities, particularly in the activated sludge. Additionally, the MC shifted microbial community assembly from stochastic to deterministic factors, amplifying the selection pressure induced by TC on the microbial community, thus enriching organic compound-degrading genera Dokdonella and TM7a; it also stimulated ammonia monooxygenase-mediated and cytochrome P450-mediated TC metabolisms and upregulated functional genes encoding lyases, transferases, hydrolases, and oxidoreductases- all of which enhanced TC biodegradation capacity in the MC-IFAS, particularly in the biofilm. While enhancing TC removal efficiency, the MC mitigated the proliferation and dissemination of antibiotic resistance genes (ARGs) by suppressing the abundances of ARGs hosts, the mobile genetic element intI1, and genes encoding ATP-binding cassette transporters and putative transposases. This study provides novel insights into the large-scale applications of magnetic field-enhanced TC removal strategies.

Keywords: Antibiotic resistance gene; Carrier; Integrated fixed-film activated sludge; Magnetic field; Tetracycline.