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The Environmental Protection Agency will propose Cryptosporidium CTTables for the Long Term 2 Enhanced Surface Water Treatment Rule(LT2ESWTR). Preliminary indications show that the required CT values will behigher than originally thought for Cryptosporidium inactivation. Severalwater utilities would be impacted by higher CT-values with respect toozone operations and bromate control strategies. The Southern NevadaWater Authority (SNWA) is currently implementing 900 MGD ofozonation between two treatment facilities. The design of these facilitieswas based on initial Cryptosporidium inactivation research to achieve a2.0-log inactivation. Substantial pilot plant testing has already beenperformed with respect to ozone operations and bromate mitigationstrategies. Previous testing indicated that a combination of 0.1 mg/Lammonia and 0.5 mg/L chlorine could be used to maintain bromate levelsbelow the 10 ppb Maximum Contaminant Level (MCL) while achieving a2.0-log Cryptosporidium inactivation. This combination was evaluatedwith three other previously determined optimal strategies at sevendifferent CT values. The results were compiled into operational matricesshowing the impact on ozone dose, ozone residual quenching dose, andbromate control strategies. Overall, the results showed substantialincreases in bromate formation, along with significant revisions to thecurrent bromate control strategies. Includes 3 references, table, figures.

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Edition: Vol. - No. Published: 06/15/2003 Number of Pages: 7File Size: 1 file , 460 KB