Bromate Formation and Control During Ozonation in Advanced Wastewater Purification for Potable Reuse
Lin Li1, Laura Haak1, Tatiana C Guarin1,2
1Department of Civil and Environmental Engineering, University of Nevada Reno, Reno, Nevada, USA.
Summary
Bromate formation during advanced water purification is a concern. This study shows that while higher ozone doses increase bromate, biological activated carbon (BAC) filtration effectively reduces it, especially with longer contact times, aiding potable reuse safety.
Area of Science:
- Environmental Engineering
- Water Treatment Chemistry
Background:
- Bromate formation is a significant challenge in ozone-based advanced water purification facilities (AWPFs).
- Potable reuse applications necessitate effective mitigation strategies for bromate, a potential human carcinogen.
Purpose of the Study:
- To investigate bromate formation and reduction dynamics in a pilot-scale ozone/biological activated carbon (BAC) system.
- To evaluate the impact of ozone doses and Empty Bed Contact Times (EBCTs) on bromate levels in potable reuse scenarios.
Main Methods:
- Utilized a pilot-scale ozone/BAC treatment system at two water reclamation facilities (WRFs).
- Varied ozone doses and EBCTs, including a bromide spiking study, to assess bromate formation and removal.
- Analyzed bromate concentrations in ozone effluent and after BAC filtration.
Main Results:
- Increasing ozone doses significantly elevated bromate concentrations, peaking at 5.2 μg/L.
- BAC filtration effectively reduced bromate levels, achieving reductions to 2.4–3.0 μg/L at 20 min EBCT.
- Bromide spiking confirmed the correlation between bromide, ozone dose, and bromate formation, with complete removal post-BAC.
Conclusions:
- Optimizing ozone doses and EBCTs is crucial for balancing contaminant removal, disinfection, and bromate mitigation.
- BAC filtration, particularly with longer EBCTs, demonstrates effectiveness in reducing bromate for potable water reuse.
- Site-specific factors like biofilms may influence BAC's bromate removal efficiency.
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