Establishment of a pretreatment method for tetracycline production wastewater using enhanced hydrolysis

• The hydrolysis half-life of tetracycline was shortened by condition optimization.
• The antibacterial activity was reduced to a negligible level after hydrolysis.
• No anaerobic inhibition was found after enhanced hydrolysis pretreatment.

High concentrations of antibiotics in wastewater may inhibit the functions of biological treatment systems. Herein, we established a pretreatment method for tetracycline production wastewater using an enhanced hydrolysis process with the optimization of temperature and pH conditions. An increase of 10 °C accelerated the tetracycline hydrolysis rate by 2.22–2.74-fold, and the hydrolysis half-life of tetracycline was shortened by 3.23-fold when the pH value was increased from 3 to 11 at 85 °C. The tetracycline solution lost 80.3–97.8% of its antibacterial activity after 6 h hydrolysis at 85 °C in the pH range 3–11. The correlation factor between the antibacterial activity and the tetracycline concentration was 0.941, indicating that the antibacterial activity of the hydrolyzed tetracycline solutions was mainly attributed to tetracycline. The average specific methanogenic activity (SMA) of acetoclastic methanogens in the anaerobic inhibition test was decreased by 100% when treating either tetracycline solution (tetracycline concentration of 1000 mg L−1) or tetracycline production wastewater (tetracycline concentration: 800–1000 mg L−1). After enhanced hydrolysis pretreatment (pH 9, temperature 85 °C and hydrolysis for 6 h), no suppression phenomenon was found under the same conditions. The results of this study demonstrated that the proposed approach was effective in enhancing the hydrolysis of antibiotics, and may be effective as a pretreatment technology for antibiotic production wastewater.

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