Fate of pharmaceuticals in drinking water utilities.

摘要

Studies suggest that drinking water treatment is effective at decreasing the amount of pharmaceuticals present in source water. Primary treatment processes such as coagulation and sedimentation are not effective on their own, while a combination of filtration and disinfection processes is effective at reducing the concentrations of most pharmaceuticals. The type of oxidant used also determines the degree at which a pharmaceutical is removed from source water. Ozone or the combination of ultraviolet (UV) light with hydrogen peroxide seem to be the most effective oxidation processes. Chlorine oxidation is known to produce chlorinated byproducts when it reacts with organic compounds. In bench-scale studies, the reaction of the pharmaceutical, acetaminophen with free chlorine was studied. Acetaminophen reacts with free chlorine to produce the byproduct 1,4-benzoquinone. Results indicate that acetaminophen is most reactive with free chlorine at pH 9.0 and least reactive at pH 6.0. As pH increased, degradation of acetaminophen also increased. The formation of 1,4-benzoquinone was also affected by pH and reached a maximum of 68.7% of the initial acetaminophen concentration when the pH was at 6.0, the molar ratio at 1,275, and after a contact time of 30 minutes. At all pH values the rate of degradation of acetaminophen was slowest at a molar ratio of about 100, and the highest at a molar ratio of about 10,000.