Tracking macrolides, sulfonamides, fluoroquinolones, and tetracyclines in sludge treatment wetlands during loading and resting periods

Abstract This study investigated the removal efficiency and mechanism of antibiotic contaminants in sludge treatment wetlands (STWs) using liquid chromatography–mass spectrometry. We examined one aeration control and two STWs: unit1 was a treatment unit with aeration tubes only; unit2 was an STW with reeds and aeration tubes, and unit3 was an STW with reeds only. The results showed that the STWs effectively removed antibiotics, with removal rates of 41.8 % (norfloxacin) and 90.4 % (sulfamethoxazole). Comparing the STWs, the mass of each antibiotic accumulated in the residual sludge of unit1 (4.0 – 199 mg) was higher than that of unit2 (2.4–101 mg) and unit3 (2.8–121 mg). This showed that unit2 with plants and aeration tubes had the highest removal effect on antibiotics. The mass balance analysis of antibiotics revealed that microbial degradation (11.8–58.0 %), substrate adsorption (20.0–34.8 %), and plant uptake (0.35–3.1 %) were important methods for antibiotic removal from wetlands, and microbial degradation was the main method for removing antibiotics.