Antibiotic fate in an artificial-constructed urban river planted with the algae Microcystis aeruginosa and emergent hydrophyte.

The behavior and removal of 6 antibiotics including azithromycin, clarithromycin, sulfathiazole, sulfamethoxazole, ciprofloxacin and tetracycline in an artificial-controllable urban river (ACUR) were investigated. The ACUR was constructed to form 5 artificial eco-systems by planting 3 emergent hydrophytes and Microcystis aeruginosa: 1) Control; 2) MA: Microcystis aeruginosa only; 3) MA-J-C: Microcystis aeruginosa combined with Juncus effusus and Cyperus alternifolius; 4) MA-C-A: Microcystis aeruginosa combined with Cyperus alternifolius and Acorus calamus L.; 5) MA-A-J: Microcystis aeruginosa combined with Acorus calamus L. and Juncus effusus. The MA-C-A system achieved the best removal of azithromycin and clarithromycin after 15-d test with the final concentrations 0.92 μg/L and 0.83 μg/L. The contents of ciprofloxacin and tetracycline in sediment were highest, up to 1453 ng/g and 1745 ng/g. The antibiotic plant bioaccumulation was higher in roots rather than the shoots (stem and leaves). No target antibiotics were detected in algae cells. The combination of hybrid hydrophytes had a certain effect on the removal of antibiotics, and thus selecting appropriate hydrophytes in urban rivers could greatly improve water quality. The overall removal of 6 antibiotics was greatly improved by the ACUR containing the hybrid hydrophytes and the algae, indicating a synergistic effect on antibiotic removal.