In order to investigate the effect of multiple fluoroquinolones on the performance and microbial community of a constructed wetland, ofloxacin, norfloxacin, and ciprofloxacin were added to the influent of the vertical flow constructed wetland for two months. Results indicated that COD removal rate gradually decreased after adding antibiotics, with the minimum removal rate of 70.94%, followed by gradual recovery. TP removal rate also decreased, with some fluctuations, while ammonia removal remained stable. Fluoroquinolones thus have an important effect on COD and TP removal from the constructed wetland, but there is no evident effect on ammonia removal. Based on results of the Shannon index and Shannoneven index, there were no significant changes in the microbial community, while the Chao1 index increasing significantly. Comparing community composition before and after antibiotic addition, the relative abundance of Proteobacteria decreased from 44.90% to 34.12%, still maintaining its predominance, while Firmicutes increased from 2.55% to 10.55%. At the class level, β-Proteobacteria declined from 17.03% to 8.36%, while the relative abundance of Clostridia, Bacilli, and Bacteroidia increased from 0.50%, 1.85%, and 0.10% to 4.21%, 4.64%, and 2.56%, respectively. The genera Dechloromonas and Pseudarthrobacter decreased from 8.56% and 5.10% to 3.16% and 1.53%, respectively, while Trichococcus, Tessaracoccus, and Desulfovibrio increased from 0.66%, 0.03%, and 0.02% to 3.84%, 3.83%, and 2.06%, respectively. The microbial community of the constructed wetland thus changed under the pressure of multiple fluoroquinolones.
Keywords: community composition; constructed wetland; diversity; fluoroquinolones; performance.