Sonocatalytic treatment of phosphonate containing industrial wastewater intensified using combined oxidation approaches

Treatment of actual industrial wastewater is a challenging task and has not been investigated using the cavitation-based approaches significantly. In the present work, sonocatalytic degradation (catalysts as CuO and TiO2) of phosphonate based industrial wastewater, procured from a local company, has been studied in terms of COD reduction under optimized conditions (established using initial studies involving only ultrasound) of pH as 3.2, the temperature of 32 +/- 2 degrees C and 120 min as treatment time. The combination of ultrasound with H2O2 and ozone in different approaches has been investigated for maximizing the COD reduction. The optimum set of operating conditions for the sonocatalytic degradation were established as power dissipation of 90 W and catalyst loading as 0.75 g/L for CuO and 0.5 g/L for TiO2. Use of only ultrasound resulted in COD reduction of 37.2% whereas the combination of US with different approaches resulted in higher extents of COD reduction. The combined operation of US + H2O2 + O-3, US + O-3 + H2O2 + CuO, and US + O-3 + H2O2 + TiO2 resulted in the extent of COD reduction as 91.5%, 93.8%, and 95.8% respectively. Overall, it has been clearly established that maximum COD reduction is obtained for the combined operation of sonocatalysis (catalyst as TiO2) with ozone and H2O2.