Grantee Research Project Results

Kinetic-Based Models for Bromate Formation in Natural Waters

EPA Grant Number: R826835
Title: Kinetic-Based Models for Bromate Formation in Natural Waters
Investigators: Westerhoff, Paul
Institution: Arizona State University
EPA Project Officer: Hahn, Intaek
Project Period: September 1, 1998 through August 31, 2000
Project Amount: $99,500
RFA: Drinking Water (1998) RFA Text |  Recipients Lists
Research Category: Drinking Water , Water

Description:

Ozone (O3) is an effective disinfectant, but it can form by- products (e.g., bromate). There is a need to develop tools to understand and predict bromate (BrO3-) formation while still achieving high levels of microbial disinfection. The central hypothesis is that a kinetic-based understanding of natural organic matter (NOM) reactions with hydroxyl (HO) radicals and aqueous bromine (HOBr/OBr-) over a range of temperatures is necessary to develop mechanistic-based models for bromate formation in bulk waters. Objectives include: Develop a comprehensive database of BrO3-, O3, and HO radical concentrations; Determine rates of reaction between HOBr and OBr- and NOM; Calibrate and verify a BrO3- formation mechanistic-based model that includes NOM; Simulate BrO3- control measures necessary to meet proposed and future MCLs; Link the numerical BrO3-formation model with hydraulic and CT disinfection models.

Approach:

A mechanistic-based, numerical, kinetic BrO3- formation program will be developed. The program links an oxidant module for predicting O3 and HO radical concentrations with a BrO3- formation module. The model employs a set of bromide oxidation reactions that have been previously developed by the Investigator, and calibrated against bromine and BrO3- formation in NOM-free water; NOM reactions will now be incorporated. The oxidant module will be calibrated against experimental O3 decay data (e.g., simple first-order decay) and HO radical concentrations (calculated from the disappearance of a HO radical probe compound during ozonation). Predicted BrO3- levels will be calibrated and verified against an internal database, that accounts for synergistic effects of key parameters (bromide, pH, ozone dose, temperature, inorganic carbon, and ammonia) on ozone decay, HO radical concentrations, and BrO3- formation, and an external USEPA database.

Expected Results:

We propose a paradigm shift from previous and ongoing studies that employ empirical models for BrO3- formation. Unlike other DBPs, the inorganic mechanisms for bromide oxidation are well defined. Basic expressions for oxidant (O3, HO radicals,HOBr/OBr-) reactions with NOM will be determined and incorporated into an existing numerical model. The final program will accurately predict BrO3- formation in the presence of NOM and could be easily adapted for studying innovative control strategies.

Publications and Presentations:

Publications have been submitted on this project: View all 9 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

Drinking water, oxidation, pathogens, human health, carcinogen,, RFA, Scientific Discipline, Water, Health Risk Assessment, Environmental Chemistry, Analytical Chemistry, Drinking Water, microbial contamination, natural waters, public water systems, monitoring, predicting chemical concentrations, chemical byproducts, disinfection byproducts (DPBs), kinetics, database development, natural organic matter, analytical methods, bromate formation, brominated DPBs, carcinogenicity, treatment, microbial risk management, hydroxyl radicals, DBP risk management, water quality, drinking water contaminants, drinking water treatment, water treatment, drinking water system, ozonation

Relevant Websites:

http://www.eas.asu.edu/~civil/

Progress and Final Reports:

1999 Progress Report

Final Report