Effects of anaerobic digestion on chlortetracycline and oxytetracycline degradation efficiency for swine manure

• Thresholds of complete removal were 60 and 40 mg/kg·TS for CTC and OTC respectively.
• High antibiotic concentrations above thresholds equate to low biogas production.
• CTC and OTC with low concentration below thresholds could increase BMP of manure.
• The results help to determine the applicability of AD treatment for manure with antibiotic.

Manure containing antibiotics is considered a hazardous substance that poses a serious health risk to the environment and to human health. Anaerobic digestion (AD) could not only treatment animal waste but also generate valuable biogas. However, the interaction between antibiotics in manure and the AD process has not been clearly understood. In this study, experiments on biochemical methane potential (BMP) were conducted to determine the inhibition of the AD process from antibiotics and the threshold of complete antibiotic removal. The thresholds of the complete antibiotic removal were 60 and 40 mg/kg·TS for CTC and OTC, respectively. CTC and OTC with concentrations below thresholds could increase the BMP of manure. When the CTC and OTC concentrations exceeded the thresholds, they inhibited manure fermentation, and the CTC removal rate declined exponentially with concentration (60–500 mg/kg·TS). The relationship between OTC antibiotic concentration and its removal rate in AD treatment was described with exponential (40–100 mg/kg·TS) and linear equations (100–500 mg/kg·TS).

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