Behavior of tetracycline and macrolide antibiotics in activated sludge process and their subsequent removal during sludge reduction by ozone

Ozonation is a promising means for the reduction of excess sludge in wastewater treatment plants. However, little information is available on the removal of antibiotics during sludge ozonation. Therefore, this study investigated first the behavior of four commonly-used hydrophobic antibiotics, inclu...

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Bibliographic Details
Published in:Chemosphere (Oxford) 2018-09, Vol.206, p.184-191
Main Authors: Wang, Lu, Ben, Weiwei, Li, Yangang, Liu, Chao, Qiang, Zhimin
Format: Article
Language:English
Subjects:
Activated sludge process
Antibiotics
Ozonation
Sludge reduction
Sorption
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Summary:Ozonation is a promising means for the reduction of excess sludge in wastewater treatment plants. However, little information is available on the removal of antibiotics during sludge ozonation. Therefore, this study investigated first the behavior of four commonly-used hydrophobic antibiotics, including three tetracyclines (tetracycline, oxytetracycline, and doxycycline) and one macrolide (azithromycin) in activated sludge process and then their removal during sludge reduction by ozone. Results indicate that the studied antibiotics were primarily transferred into the solid phase of activated sludge via sorption, which was a reversible, spontaneous, and exothermic process governed by surface reactions. Sludge ozonation could effectively remove 86.4–93.6% of the antibiotics present in the sludge at an ozone dose of 102 mg per gram of mixed liquor suspended solids and pH 7.2. The removal of studied antibiotics mainly proceeded through desorption and subsequent oxidation. Increasing the initial pH from 5.0 to 9.5 obviously enhanced the antibiotic removal during sludge ozonation. This study demonstrated that the activated sludge process coupled with sludge ozonation can simultaneously reduce excess sludge and eliminate antibiotics. [Display omitted] •TCN, OTC, DOX and AZN were primarily transferred into the sludge via sorption.•The cations of antibiotics had higher sorption affinity to sludge than other species.•86.4–93.6% of antibiotics in sludge can be removed at 102 mg O3 g−1 MLSS and pH 7.2.•Alkaline pH favored the elimination of antibiotics during sludge ozonation.
ISSN:0045-6535
1879-1298
DOI:10.1016/j.chemosphere.2018.04.180