Treatement of industrial effluents by advanced oxidation techniques

Abstract

Tannery effluent is acknowledged as one of the significant pollutants causing contamination of water bodies and ground water in many nations. Conventional treatment techniques like coagulation, aeration and biological treatment methods do not suffice the required degradation, whereas advanced techniques like reverse osmosis and thin film drying require humongous energy. In the present work, advanced oxidation of tannery effluent is carried out using titanium dioxide, zinc oxide and silicon dioxide catalysts with the aid of ultrasound and ozone, fenton reagent and ultrasound in a multi-orifice oscillatory baffled column, which intensifies the reaction between the effluent and oxidizers. The catalysts were prepared in laboratory scale using reagents and characterized using Scanning Electron Microscopy and X-ray Diffraction studies. The catalysts were utilized for advanced oxidation in a sono-chemical reactor. Studies have been carried out to understand the effect of treatment time, concentration of effluent and oscillation frequency upon ozonation, Sono- Ozonation and Fenton Ozonation and the effect of power of ultrasound, time of treatment and catalyst loading for sono-catalytic treatment. The spent catalysts were analyzed using Scanning Electron Microscopy and X-ray Diffraction to understand the condition of catalyst after treatment. Deposition of contaminants on the catalysts and slight changes in the surface morphology was evident. For Sono-TiO2, Sono -ZnO and Sono - SiO2 treatments the reduction of COD, BOD and TDS obtained are 91.2%, 91.5%, 94%. , 89% 85% 88% and 88%, 89% 88% respectively where as for ozonation, sono-ozonation and Fenton- ozonation are 76.8%, 79.7%,90.1%,88.8%, 84.0%, 90.7% and 90.8%,86.9%,88..6%. Optimization and analysis of variables is carried out to identify the effective factors for treatment. Thus the introduction of a Multi-orifice baffled column and hybridization of the treatment with ultrasound can be a breakthrough in effluent treatment technologies newline