Kinetic Modeling-Assisted Optimization of the Peroxone (O₃/H₂O₂) Water Treatment Process

Abstract

In this work, we investigate the influence of H 2 O 2 dosage, H 2 O 2 dosing method, and electron-rich dissolved organic matter (DOM) on the performance of the peroxone (O 3 /H 2 O 2 ) process using oxalate (OA) as the target organic compound. Our results show that the method used for H 2 O 2 dosing (i.e., single, multiple, and/or continuous injection(s)) has a significant influence on OA removal after 1 h with nearly 100% of OA oxidized by continuous injection of a total of 1 mM H 2 O 2 , but only 48 and 80% OA were removed when the same amount of H 2 O 2 (1 mM) is applied in single and multiple injection(s), respectively. Inhibition of futile scavenging of • OH by H 2 O 2 when H 2 O 2 is dosed in smaller amounts either frequently or continuously throughout the process results in a higher efficiency of organic oxidation compared to that achieved with a single injection of a high concentration of H 2 O 2 at the outset. Our results further show that the presence of high concentrations of humic acids (HA, a representative electron-rich DOM) promotes O 3 decay and concomitant • OH generation rates and, as a result, significantly enhances the oxidation rate of OA by ozone alone. As such, any enhancement in • OH generation and associated OA oxidation that might be achieved by H 2 O 2 addition in the presence of HA will be dependent on the extent of • OH generation that results from HApromoted O 3 decay. Based on our results, we have developed a mathematical model that can be used to predict • OH generation and OA oxidation by the peroxone process over a range of conditions. The model provides a good description of the influence of various operating parameters (including ozone dosage, H 2 O 2 dosage, H 2 O 2 dosing method, and the presence of HA) on OA oxidation and, potentially, can be used to optimize the choice of operating conditions in full-scale peroxone systems.