Enhanced removal of typical antibiotics and the changes of bacterial communities in an electro-assisted vertical flow constructed wetland

Abstract

The presence of a considerable amount of antibiotic residues in urban sewage treatment systems represents a significant threat to both ecological security and human health. In this study, three common aquatic plants, Iris pseudacoru, Cannan indica, and Cyperus alternifolius, and three commonly used antibiotics, oxytetracycline (OTC), tetracycline (TET), and sulfadimethoxine (SDM) were selected to construct a hydroponic system to screen plants with the best antibiotic removal effect. The impact of electric-assisted vertical flow constructed wetland (E-VFCW) on the removal of target antibiotics under varying conditions was investigated. Furthermore, the effects of electrical stimulation on plant physiological indexes and the structure of the microbial community were analyzed. The results showed that the three stages of anodic had the best removal rates for OTC (23.9%, 18.5%, and 14.5%) and TET (28.4%, 23.4%, and 17.4%). When the voltage was 0.9 V and the hydraulic residence time was 36 h, the removal rates of OTC and TET in the anaerobic anodic and aerobic cathodic chamber systems were increased by 15.7% and 18.9%, respectively. The OTC and TET removal rates in the anaerobic cathodic and aerobic anodic chamber systems were increased by approximately 10.3% and 15.5%, respectively. The E-VFCW had no significant effect on SDM. The degradation efficiencies of OTC and TET in the anaerobic zone were higher than those in the aerobic zone. Electrical stimulation enhances enzymatic activity in plants and improves their resistance. Electrical stimulation selectively enriched certain antibiotic-degrading microorganisms, including Elstera, Erysipelothrix, Anaerolinea and Desulfomicrobium.