Oxidative degradation of emerging micropollutants induced by rotational hydrodynamic cavitating device: A case study with ciprofloxacin

The trace amount of micro-pollutants (organic mostly) those still remain in the final effluent of any industry even after the tertiary treatment is a serious matter of concern and needs special treatment strategy to address the same. Advanced oxidation processes have emerged as the best suited remedy for that. However, among all the AOPs, cavitation process is till now one of the most unattempted technologies in spite of inherent enormous potential. The present work reports a study with the degradation of the antibiotic Ciprofloxacin (CIP) using a novel skid-mounted rotating hydrodynamic cavitation (RHC) reactor. Using only hydrodynamic cavitation, 44.8% CIP degradation was achieved within 60 min. Now RHC combined with oxidizing agents like O-3 (0.75 g/ h), H2O2 (0.3 g/L) and Fenton's reagent (1:3) resulted in 91.4%, 85.6%, and 87.6% degradation within 30 min. The HC+H2O2 (0.3 g/L) surpassed the performances of other combinations from energetic and economic viewpoint. Liquid chromatography-mass spectra (LC-MS) studies were performed to evaluate the degradation mechanism. Lastly, a pilot scale study (400 L) with real life water sample post tertiary treatment collected from pharmaceutical industry was carried out to understand the techno-economic feasibility.

Automated summary

This study utilized a novel rotating hydrodynamic cavitation reactor to treat wastewater containing antibiotics, achieving rapid degradation by combining RHC with oxidizing agents. The results showed that the HC+H2O2 combination performed the best energetically and economically, while LC-MS studies revealed the degradation mechanism. A pilot scale study was also conducted to assess the techno-economic feasibility of the treatment process on real life water samples from the pharmaceutical industry.