Occurrence of Nine Antibiotics in Different Kinds of Sewage Sludge, Soils, Corn and Grapes After Sludge Spreading

The huge worldwide use of antibiotics triggers the accumulation of these substances in sludge from wastewater treatment plants (WWTP) and the possible contamination of soils amended with it, as well as of crops growing in these soils. In this work we analyzed the presence of the antibiotics amoxicillin (AMO), cefuroxime (CEF), ciprofloxacin (CIP), clarithromycin (CLA), levofloxacin (LEV), lincomycin (LIN), norfloxacin (NOR), sulfadiazine (SUL), and trimethoprim (TRI), in sludge from different WWTPs in Galicia (NW Spain), as well as in sludge technically treated by waste-managers, in soils where treated sludge was applied, and in crops (corn and vineyard) growing in the amended areas. The antibiotics were quantified by means of high resolution HPLC-mass-chromatography. The results indicate that almost all the sludge samples contained antibiotics, being ciprofloxacin and levofloxacin the most abundant reaching maximum values of 623 and 893 ng/g, respectively. The sludge treatment significantly reduced the number and the concentrations of antibiotics. In 12% of the soil samples where sludge was applied, some antibiotics were detected, but always in small concentrations. Regarding the crops, no antibiotic was detected in the roots, stalk, leaves and grain of corn, neither in grapes sampled in vineyards. It can be concluded that the treatments currently applied in the WWTPs under study are not totally effective in removing antibiotics from the sludge, although the findings of this research suggest that the additional specific treatment of the sludge derived from these WWTPs is effective in reducing the risk of environmental pollution due to a variety of antibiotics, and specifically in the case of soils amended with these organic materials and crops growing on it.