Photoreactor design and CFD modelling of a UV/H 2O 2 process for distillery wastewater treatment

Abstract

A pseudo-kinetic model for the treatment of a distillery wastewater by the ultraviolet irradiation and hydrogen peroxide process in a continuous tubular photoreactor is developed. There is a scarcity of information on modelling of organic degradation rates based on chemical oxygen demand (COD) and total organic carbon (TOC) in advanced oxidation technologies (AOTs). In this study, the COD and TOC are used as surrogate parameters to design a photoreactor instead of individual concentrations of species. The rate constants for the reaction between COD and TOC with hydroxyl radicals were determined to be 4.9×10 9 and 5.0×10 6M -1s -1, respectively. A laminar flow model was simulated to estimate the velocity and residence time of the medium in a cylindrical photoreactor. The model was validated by the experimental data published in the open literature for different concentrations of H 2O 2 (1, 10, and 100mM), COD (589, 709, and 850mgO 2L -1), and TOC (190, 200, and 192mgCL -1). The optimal value of the inlet hydrogen peroxide concentration was predicted to be 400mgL -1. Axial and radial concentration distributions of species in the photoreactor were also obtained. At different photoreactor radii (from 50 to 200mm), the values of radial local volumetric rate of energy absorption (LVREA) were estimated. It was found that a higher LVREA was achieved in the photoreactor space at smaller radii. © 2011 Canadian Society for Chemical Engineering © 2011 Canadian Society for Chemical Engineering.