Comparative studies on ultrasound assisted treatment of tannery effluent using multiple oxy-catalysts using response surface methodology

Advanced oxidation of wastewater is a promising technique for tannery wastewater treatment, as it consumes less chemical addition and energy and it doesn’t liberate any secondary effluents. However, advanced oxidation can be improved by conjoining it with energy sources like ultraviolet radiation, ultrasound, etc. Catalysts capable of oxidation like titanium dioxide and iron oxide have been utilized for advanced oxidation of tannery effluent. The present work studies the synergic effect of ultrasound assisted advanced oxidation using two oxy-catalysts, namely zinc oxide and silicon dioxide. The effect of variables like time of treatment, catalyst loading, and power of ultrasound on the reduction of BOD, COD, and TDS were estimated and the results indicated a proficient reduction of contaminants. Upon treatment with silicon dioxide under ultrasound, the COD, BOD, and TDS reduction were found to be 88%, 89%, and 88% respectively, while zinc oxide catalyst indicated 89%, 85%, and 88% reduction. Response Surface Methodology has been utilized for derivation of a mathematical model for COD, BOD and TDS reduction. The spent catalysts were analyzed using Scanning Electron Microscopy and X-ray Diffraction to understand the changes in the characteristics of the spent catalyst. The deposition of contaminants on the catalysts and slight changes in the surface morphology were evident. Hence silicon dioxide and zinc oxide are promising catalysts for the treatment of tannery effluent combined with ultrasound.