Computational fluid dynamics modeling alternatives for UV-initiated advanced oxidation processes

Abstract

Design and optimization of ultraviolet-initiated (UV-initiated) advanced oxidation processes (AOPs) using hydrogen peroxide (H2O2) must consider both system configuration and chemical kinetics. Alternative approaches to modeling AOP systems have been proposed in the literature; yet, due to the complex nature of the reactions involved, the literature lacks clarity in the appropriate selection of a modeling approach to help define the UV/AOP system performance. Computational fluid dynamics (CFD) was compared to the numerical solution of a system of ordinary differential equations describing the reaction mechanism for hydroxyl radical production and methylene blue destruction and to a UV dose distribution analysis produced by a Lagrangian particle track in CFD with a given dose–response curve. Similar analyses were also performed to simulate the destruction of tris(2-chloroethyl) phosphate (TCEP) and tributyl phosphate (TBP), in two different photoreactors. To validate the simulations, the results of the models were compared to pilot reactor trials for methylene blue bleaching and literature data for TCEP and TBP. Modeling results suggest that the agreement of both CFD Eulerian and Lagrangian approaches to simulating the UV/H2O2 AOP is a function of reactor design, the water matrix, and operating conditions.