Research had shown that ozone had the potential to effectively kill Giardia and viruses more effectively than chlorine,
without producing regulated chlorinated DBPs. Ozone would allow Waterworks to meet the future 40/30 standard
and as it turned out, the final Stage 2 as promulgated in 2006. Foundation work was also instrumental in convincing
Waterworks that it would have no trouble meeting a bromate standard of 10 µg/L, also regulated by Stage 1, while
using ozone. The research showed that while employing intermediate ozonation at a pH of approximately 6. 2, bromate
formation is virtually nonexistent, regardless of bromide levels.
Waterworks has spent millions of dollars to comply with the DBP rules over the last thirty years. Waterworks’
investment in Foundation funding has been repaid handsomely by allowing the implementation of successful
technologies and avoiding any negative simultaneous compliance issues at the same time.
CASE STUDIES AND VAlUE OF RESEARCH
Bromate Minimization Strategies
Richard talley, City of Fort Worth, texas
The City of Fort Worth Eagle Mountain Water Treatment Plant (WTP) was constructed and placed into operation in
1992. The plant process consists of raw water ozonation, conventional rapid mix, flocculation and sedimentation,
and biological filters using deep bed anthracite media. Chlorine and ammonia are added to the filtered water for
chloramines residual disinfection. Ferric sulfate and cationic polymer are used as the coagulant and coagulant aid.
Lime is added upstream of the rapid mix basins for pH control.
The original Eagle Mountain WTP was designed for a treatment capacity of 30 million gallons per day (mgd). The plant
was expanded in 2000 and again in 2007 to increase plant capacity to 70 mgd and 105 mgd respectively.
Raw water is supplied from Eagle Mountain Lake. This lake has a relatively stable water quality including the
pH 7. 7 to 8. 5
Alkalinity 100 to 130 mg/L
Hardness 120 to 160 mg/L
Turbidity 2 to 10 NTU
Total Organic Carbon 4 to 6 mg/L
Bromide 0.100 to 0.220 mg/L