Enhancing antibiotic removal in constructed wetlands: A MgFe-LDHs-based strategy for optimizing microbial communities and metabolic functions

Abstract

To efficiently remove antibiotics from domestic and livestock wastewater in southern China, vertical flow constructed wetlands (CWs) were designed with and without magnesium-iron layered double hydroxides (MgFe-LDHs). Their removal efficiencies for three typical antibiotics (tetracycline, oxytetracycline, and ofloxacin) were evaluated. Results showed that MgFe-LDHs significantly improved nitrogen and phosphorus removal (18.7 %-25.6 %) and enhanced the degradation of tetracycline, oxytetracycline, and ofloxacin (13.1 %-17.8 %). High-resolution LC-MS analysis indicated significant biodegradation through various pathways, such as oxidation, hydrolysis, and dealkylation. Analysis of the Shannon diversity index demonstrated that the introduction of novel MgFe-LDHs enhanced microbial diversity and evenness at the phylum, class, and genus levels. The introduction of MgFe-LDHs increased microbial diversity and enriched antibiotic-degrading genera like Xanthobacter, Ochrobactrum, and Stenotrophomonas. Moreover, MgFe-LDHs may have enhanced the metabolic pathways of glycolysis and the tricarboxylic acid cycle, thereby improving the microbial degradation of organic matter. In summary, MgFe-LDHs exhibited a multifaceted role in enhancing antibiotic removal in CWs by inducing the enrichment of antibiotic-degrading bacteria and regulating the metabolic functions of the microbial community, while also ensuring higher nitrogen and phosphorus removal efficiency.