Factor Screening for Ozonating the Taste- and Odor-Causing Compounds in Source Water at Detroit, USA

Three odorants, geosmin (earthy), MIB (2-methylisoborneol) (musty), and IPMP (2-isopropyl-3-methoxypyrazine) (decaying vegetation/musty) were spiked into raw water taken from the Detroit River and subjected to bench-scale ozonation (with and without hydrogen peroxide). Statistical experiment design was employed to investigate operating variables such as ozone dose, ozone addition point, temperature, odorant spike level, and presence of hydrogen peroxide. Two additional odorants, cis-3-hexenyl acetate (grassy) and trans,trans-2,4-heptadienal (fishy) were also tested. Results showed that ozonation was capable of mitigating the spiked odorants in the Detroit source water. Ozone dose was the single most important factor in removing the odorants. Presence of hydrogen peroxide (without dose optimization) had a limited effect on odorant removal at tested pH and alkalinity conditions. Ozone application point and water temperature had significant impacts on ozone residual, but not on odorant removal. MIB was most difficult to remove by ozonation among the five spiked odorants.