Ozonation and photo-driven oxidation of ciprofloxacin in pharmaceutical wastewater: degradation kinetics and energy requirements

Pharmaceutical wastewater has become an important source for emitting antibiotics into aquatic environments. However, this study aims to evaluate the potential of different advanced oxidation processes like ozonation, photolysis, and photo-catalysis for degrading a fluoroquinolone antibiotic ciprofloxacin (CIP) in real pharmaceutical wastewater. The raw wastewater contains a high concentration of organic content (COD: 603 mg/L, BOD: 116 mg/L) and significant concentration of CIP (7.91 mg/L). In ozonation, compared with the acidic and basic conditions, the degradation rate was faster under basic conditions and showed a competently degraded CIP (up to 98.7%) under the optimum pH 9 within 30 min, whereas photo-catalysis by using commercial anatase (TiO₂) is considered to be the most effective technique for decreasing the concentration of CIP up to 100% within 30 min under the optimized TiO₂ dose (1000 mg/L). The degradation rate was quicker and found to be several times faster than in direct photolysis. Furthermore, electrical energy per order was also calculated for all processes and was obvious by the results that photo-catalysis consume less energy of about 8.7 kWh/m3, for almost complete deduction of CIP.