Facilitated Prediction of Micropollutant Degradation via UV-AOPs in Various Waters by Combining Model Simulation and Portable Measurement

Abstract

The degradation of micropollutants in water via ultraviolet (UV)-based advanced oxidation processes (AOPs) is strongly dependent on the water matrix. Various reactive radicals (RRs) formed in UV-AOPs have different reaction selectivities toward water matrices and degradation efficiencies for target micropollutants. Hence, process selection and optimization are crucial. This study developed a facilitated prediction method for the photon fluence-based rate constant for micropollutant degradation (k′p,MP) in various UV-AOPs by combining model simulation with portable measurement. Portable methods for measuring the scavenging capacities of the principal RRs (RRSCs) involved in UV-AOPs (i.e., HO·, SO4·−, and Cl·) using a mini-fluidic photoreaction system were proposed. The simulation models consisted of photochemical, quantitative structure–activity relationship, and radical concentration steady-state approximation models. The RRSCs were determined in eight test waters, and a higher RRSC was found to be associated with a more complex water matrix. Then, by taking sulfamethazine, caffeine, and carbamazepine as model micropollutants, the k′p,MP values in various UV-AOPs were predicted and further verified experimentally. A lower k′p,MP was found to be associated with a higher RRSC for a stronger RR competition; for example, k′p,MP values of 130.9 and 332.5 m2·einstein–1, respectively, were obtained for carbamazepine degradation by UV/H2O2 in the raw water (RRSC = 9.47 × 104 s−1) and sand-filtered effluent (RRSC = 2.87 × 104 s−1) of a drinking water treatment plant. The developed method facilitates process selection and optimization for UV-AOPs, which is essential for increasing the efficiency and cost-effectiveness of water treatment.

Keywords

• UV-AOPs
• Micropollutant degradation
• Reactive radicals
• Water matrix
• Model simulation