Feasibility of using combined TiO2 photocatalysis and RBC process for the treatment of real pharmaceutical wastewater

Abstract

The present study deals with the treatment of real pharmaceutical wastewater using photocatalysis followed by biological process. Actually feasibility studies in terms of Biodegradability Index (B.I.) were undertaken to see the efficacy of biological treatment, subsequent to photocatalytic treatment. The B.I. of the studied effluent came out to be 0.178 which was subsequently raised to 0.510 using photocatalysis as a primary treatment. Optimization for the photocatalytic process was conducted using BBD. The optimum values of parameters were found to be TiO2 dose=0.6g/L, pH=3.20, t=455min. Experimentally% degradation at optimum conditions was found to be 63.7% which was very close to the suggested value of 67.02%.Analysis by GC–MS suggested the formation of short chained compounds after the photocatalytic treatment. Toxicity assay and B.I. confirmed the non toxicity and biodegradability of wastewater after photocatalytic treatment, respectively. The experimental data showed a reasonably good expression of second order kinetics. Biological treatment was followed by using Rotating Biological Contractor (RBC) for further degrading the COD, BOD to the limits according to standards suggested by concerned authorities. Overall% degradation efficiency of combined photocatalysis and biological process was 96.5% of which 67% corresponded to the photocatalysis and remaining 30% to the biological RBC.