The objective of this study was to evaluate concentrations of antibiotics in differentially treated wastewater and reclaimed water. Wastewater (from several treatment processes), final effluent and reclaimed water samples (n=72) from four U.S. wastewater treatment plants (WWTPs) and one associated spray irrigation site was analyzed for the presence of nine commonly used antibiotics using isotope dilution-liquid chromatography-tandem mass spectrometry. Most effluent antibiotic concentrations were lower than influent concentrations. Azithromycin concentration was an order of magnitude higher than all other influent antibiotic concentrations. Antibiotic concentrations in samples from various treatment processes depended on individual antibiotic characteristics, namely hydrophobicity, vapor pressure, polarity and stability against hydrolysis. Effluent antibiotic concentrations were lower than influent concentrations at a Mid-Atlantic WWTP supplying treated effluent to a spray irrigation site and transport to the SI site resulted in decrease in most antibiotic concentrations. On-site ultraviolet treatment did not impact antibiotic concentration but subsequent open-air storage resulted in increased concentrations of ampicillin, linezolid and oxacillin. This research can form the basis of further exploration of the long term impact of reclaimed water irrigation of food crops and on-farm practices to reduce the occurrence of and subsequent accumulation of antibiotics in reclaimed water and food crops respectively.
Citation: Environmental Health Perspectives
Pub Type: Journals