Tannery wastewater treatment by cavitation combined with advanced oxidation process (AOP)

•Ultrasound and hydrodynamic cavitation as an AOP for the treatment of tannery wastewater.•pH and H2O2 dosage shown important effects on suspended TOC reduction.•Compared the effect of ultrasound cavitation and magnetic stirring for TOC removal.•Addition of H2O2 with hydrodynamic cavitation has shown the effective removal of TOC.•TOC removal was found to be 87% using hydrodynamic cavitation with H2O2 addition. Studies on the degradation of organic pollutants (phenolic, tannins etc.,) present in the wastewater released from tannery industry have been carried out in this work. The combined effect of cavitation and magnetic stirring with the advanced oxidation processes (AOPs) has been compared. The different parameters that affect the chemical oxidation process of the tannery wastewater, like pH, ultrasound irradiation time and dosage of hydrogen peroxide (H2O2) were studied. The samples were treated by two different approaches by varying these parameters. In the first approach, wastewater was treated in the presence of cavitation using ultrasound probe sonicator and in the second approach in the presence of magnetic stirring using magnetic stirrer was used. In both the cases, the suspended total organic carbon (TOC) was measured before and after varying the parameters to ensure the destruction of organic pollutants present in the wastewater sample. The optimum conditions obtained with ultrasonic cavitation was further used in hydrodynamic cavitation set-up in order to increase the efficiency. The experimental results show that the combination of cavitation and H2O2gives a higher reduction in suspended TOC values of tannery wastewater than with addition of only hydrogen peroxide (H2O2).