Empirical Modeling of Bromate Formation and Chemical Control Strategies at Multiple Water Reuse Facilities Using Ozone

ABSTRACT

As an increasing number of potable water reuse projects consider feasibility of implementing ozonation for achieving disinfection goals and removal of trace organic compounds, bromate formation presents a practical barrier. In this study, data received from five potable water reuse facilities showed that ozone dissolution method such as fine bubble diffusion resulted in lower concentrations of bromate compared to side-stream addition. When using multipoint ozone dissolution some reduction in bromate formation was also observed. Data from these facilities displayed a positive correlation between ozone (as a function of O₃:TOC ratio) and bromate formation (as molar ratio of bromide converted to bromate) with lower formation as monochloramine or hydrogen peroxide concentrations increase. This study provides an empirical model with four equations which can be used to estimate the bromate formation and the required monochloramine or hydrogen peroxide dose to achieve adequate bromate control, i.e. below MCL of 10 µg/L, if a desired O₃:TOC ratio and initial bromide concentration are known. The empirical model estimates for monochloramine and hydrogen peroxide were found to be in good agreement with experimental data (R² = 0.96 and R² = 0.87, respectively) while within a set of boundary conditions expressed by range of concentrations of typical water quality parameters.

KEYWORDS:

• Bromate
• Hydrogen peroxide
• monochloramine
• O₃:TOC ratio
• ozone
• Potable water reuse

Acknowledgments

The research team would like to acknowledge and thank Christina Morrison, Eric Wert, Eric Dickenson, Daniel Gerrity, Aarthi Mohan, Hannah Ray, Samantha Hogard, Robert Pearce, Charles Bott, Urs von Gunten and their respective organizations for their valuable contributions and support for this project.

Disclosure statement

The authors declare that there are no relevant financial or non-financial competing interests to report.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01919512.2022.2161469

Additional information

Funding

This work was supported by the Water Research Foundation project 5035.