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Denatonium benzoate (DB) is the bitterest substance in existence, and 0.05 ppm of the bittering agent in water is detectable by taste. The Consumer Specialty Products Association and Humane Society Legislative Fund agreed that antifreeze and engine coolant manufacturers would start adding a bittering agent to their products, and several states require DB addition to antifreeze and engine coolant to prevent accidental ingestion. Since 30 ppm of DB in water could cause the water to be unpalatable, a concern is that improper disposal or spillage of products with DB could lead to contamination of water sources used for drinking water through seepage or runoff. Research has shown that sandy soil would not inhibit DB seepage into drinking water sources. The research objective was to determine if oxidation could lower the DB concentration enough to make water palatable. Experiments evaluated DB removal using oxidation batch tests. Organic free water, groundwater, softened groundwater, and softened-settled groundwater were spiked with 70 ppm DB, and 2 ppm chlorine was added. DB concentrations were tested with a high-performance liquid chromatography instrument. The DB percent removal was 4.8% in groundwater with a pH of 6.3. DB removal was 2.9% for softened-settled water with a pH of 7.9. Waters with higher pH levels had less DB removal using chlorine oxidation in comparison to water with pH levels closer to 7. The exception to this was for the softened water with a pH of 9.3 where 7% DB removal occurred. DB may have sorbed to precipitates formed during softening, thus resulting in slightly more removal. DB removal using chlorine in organic-free water was 8.5%. Chlorine did not remove as much DB from natural water with organic matter as it did with organic-free water. Chlorine oxidation did not lower DB levels enough to make water palatable.

Publication Date


Project Designation

Independent Research

Primary Advisor

Kenya M. Crosson

Primary Advisor's Department

Civil and Environmental Engineering and Engineering Mechanics


Stander Symposium poster

Denatonium Benzoate Removal from Water Sources Using Oxidation with Chlorine