Micropollutants Removal from Surface Water Using a Pilot Vacuum-UV Advanced Oxidation Process

Abstract

Organic micropollutants (OMPs) are becoming more common in drinking water supplies worldwide. Vacuum-UV (VUV) radiation is an incipient chemical-free oxidation process that offers a potentially cost-effective technology for the removal of OMPs. Utilizing a pilot system consisting of two annular VUV reactors, the authors investigated continuous-flow degradation of atrazine, a widely used herbicide, as a model OMP in synthetic and natural surface water. Nearly complete removal (i.e., 97%) of 100 ppb atrazine in an inlet stream was attained for both synthetic and raw surface water samples at a Reynolds number below 4,500. To provide a better understanding of the feasibility of this VUV process for the effective elimination of OMPs, a complete descriptive computational fluid dynamics (CFD) model was developed and validated using the data obtained from the pilot study. The proposed model closely predicted the impact of varying flow rates and water matrix (natural organic matter and alkalinity) on atrazine degradation, with less than 2.8% average absolute relative deviation (AARD%). A sensitivity analysis of the operational variables indicated the critical role of flow rate and background water composition on degradation performance and energy efficiency of the VUV treatment systems. To assess cost-effectiveness of the pilot VUV system for remediation of atrazine-contaminated waters, an electrical energy-per-order (EEO) analysis was conducted, showing that a sequential installation of the two annular VUV reactors was up to 25% more energy efficient than a parallel configuration.