Optimization of Advanced Oxidation Processes (AOP) for Water Reuse
Year Release: 2011
Funding Partner: Bureau of Reclamation
Total Investment: $233,855 (Cash: $125,000, In-Kind: $108,855)
Principal Investigators: Fernando L. Rosario-Ortiz, University of Colorado at Boulder (formerly of the Southern Nevada Water Authority), Eric C. Wert, Southern Nevada Water Authority, Shane A. Snyder, University of Arizona (formerly of the Southern Nevada Water Authority), Stephen P. Mezyk, California State University at Long Beach
The use of indirect potable reuse (IPR) to augment and sustain water supplies is being actively evaluated to confront availability problems. However, one of the main issues associated with IPR is the presence of micropollutants that are of potential health and ecological concern. The application of advanced oxidation processes (AOPs), including ozone, ozone with hydrogen peroxide (H2O2), and UV light with H2O2, has been shown to be effective for the removal of micropollutants. The increased effectiveness of AOPs for contaminant removal is due to the formation of hydroxyl radicals, which non-selectively react with a wide range of micropollutants. However, the hydroxyl radical also reacts with water quality components (e.g., alkalinity, total organic carbon [TOC]), limiting AOP effectiveness, a problem commonly referred to as scavenging.
Goals and Objectives
The project evaluates AOP performance from the perspective of the reactivity of hydroxyl radicals toward effluent organic matter (EfOM) and the effects on the efficiency of AOPs for micropollutant oxidation.
As part of this study, quantification of kEfOM-OH values was performed using samples collected from different wastewater utilities to evaluate potential variability in EfOM reactivity. Emphasis was placed on the quantification of kEfOM-OH utilizing non-processed bulk samples. In order to account for variations, and to provide a way to predict kinetic values, a model was developed that considered the variability between different sites and relate these to specific properties of the EfOM. The model included EfOM polarity, molecular weight, fluorescence index and specific UV absorbance.
Findings and Conclusions
The results from this study indicate that, depending on the specific properties of the EfOM (including molecular mass and polarity), AOP treatment could be optimized by varying conditions that are targeted for a specific water quality. The observed variability in EfOM reactivity also suggests that in some cases the efficacy of an AOP for micropollutant removal may be dependent on the changes to the EfOM.
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