Sonophotocatalytic Oxidation Process for the Treatment of Pharmaceutical Wastewater

Abstract

Now a day, due to the presence of extremely refractory organic matter in the wastewater stream, the use of conventional wastewater treatment methods are increasingly become challenged. So, now there is a clear need to test and set up the emerging alternative technologies that can deal with highly concentrated and toxic non biodegradable organic matter. So in this way advanced oxidation process (AOP’s) has emerged in the last decade especially for the treatment of industrial wastewater. Recently, considerable interest has been shown by researchers all over the world in the application of ultrasound on the photocatalysis i.e. Sonophotocatalysis, to improve the performance of photocatalytic degradation of organic and inorganic contaminants in aqueous streams. Basically Sonophotocatalysis is the combination of two AOP’s i.e. Sonolysis (use of ultrasound) and photocatalysis (use of UV). The basic reaction mechanism for both Sonolysis as well as Photocatalysis is the generation of free radicals and subsequent attack by these on the pollutant organic species. If the UV and ultrasound are operated in combination, more number of free radicals will be available for the reaction thereby increasing the rates of reaction. The beneficial effect of combining the two modes of irradiations is that it will eliminate the drawbacks of individual process. A lot of research has been done on this technology in the recent years for the degradation of compounds like phenols and substituted phenols, alkyl halides, aromatics halides, substituted halides, inorganic chemicals, dyes, herbicides and pesticides etc and this treatment technology shows that it has potential for the degradation and mineralization of these recalcitrant compounds. So, we can say that Sonophotocatalysis has large capability for the water treatment. The scope of this project is to see Sonophotocatalysis as a viable treatment option in case of pharmaceutical industry wastewater. The experiments and analysis work is done with actual industrial wastewater. Titanium dioxide was used as photocatalyst. Experiments were performed in slurry mode in both UV and solar light at optimized condition. The degradation of wastewater has been investigated in terms of reduction in COD. Various process parameters like catalyst dose, pH, concentration of oxidant, initially pollutant concentration were varied and their effects Sonophotocatalytic treatment of pharmaceutical w/w have been analyzed. In this case the catalyst concentration was optimized at 0.2g/100ml, pH at 4 and oxidant concentration at 0.5ml/100ml of the sample. The results obtained were quit appreciable as it reduced COD by 99%, BOD by 98.8%, Sulfate by 93.7%, Chloride by 98.7% and TDS 99.5%. The results of Sonophotocatalytic degradation of wastewater showed that it could be used as efficient and environmental friendly technique for the complete degradation of recalcitrant organic pollutants which will increase the chances for the reuse of wastewater. The investigations demonstrate the importance of selecting the optimal degradation parameters for practical applications of this operation.