Evaluating the Biodegradation of Veterinary Antibiotics Using Kinetics Model and Response Surface Methodology

Area of Science:

• Environmental Science
• Environmental Chemistry
• Biotechnology

Background:

• Antibiotic resistance is a global threat exacerbated by incomplete removal from wastewater.
• Veterinary antibiotics like ciprofloxacin and enrofloxacin contaminate water sources.
• Wastewater treatment plants struggle with efficient removal of these pharmaceutical pollutants.

Purpose of the Study:

• To investigate the biodegradation of ciprofloxacin (CIP) and enrofloxacin (ENRO) in an anaerobic digestion process.
• To optimize operating conditions for enhanced antibiotic removal.
• To understand the biodegradation kinetics of these veterinary antibiotics.

Main Methods:

• Batch reactors were used to study biodegradation under varying pH, organic loading rate (OLR), and antibiotic concentration.
• Response Surface Methodology (RSM) with a Box-Behnken design analyzed parameter influence.
• First-order kinetics and polynomial models were applied to the experimental data.

Main Results:

• Optimal conditions (pH 6, OLR 2 kgCOD·m⁻³·days⁻¹, 75% antibiotic conc.) yielded 80% CIP, 83% ENRO, and 73% COD removal.
• OLR and pH showed synergistic and antagonistic effects on biodegradation.
• Biodegradation followed first-order kinetics (R²: 0.9885–0.9978) with rate constants from 0.0695 to 0.96 days⁻¹.

Conclusions:

• Anaerobic digestion can effectively remove ciprofloxacin and enrofloxacin from wastewater.
• RSM successfully identified optimal conditions for maximizing antibiotic removal.
• The study provides valuable kinetic data for designing advanced wastewater treatment systems for pharmaceutical contaminants.