Catalyzed Ozonation Decomposition of Taste and Odor-Causing Substances in Water and Simultaneous Control of Aldehyde Generation

Abstract

Ozone oxidation is commonly used to remove taste and odor (T&O) from drinking water. However, this technique is only moderately effective, and is complicated by the formation of aldehyde by-products. In this study, we investigated the efficiency of ozonation with which aluminum oxide catalysts (γ-AlOOH [HAO], γ-Al2O3 [RAO], and α-Al2O3 [AAO]) removed three representative odorous substances (2-methylisoborneol [MIB], 2,4,6-trichloroanisole [TCA], and 2-isopropyl-3-methoxypyrazine [IPMP]) from water and reduced the yields of aldehydes. Application of ozonation alone led to incomplete mineralization of odorous substances and generation of large amounts of aldehydes. In comparison, catalyzed ozonation by the three aluminum oxides substantially increased the removal efficiencies of T&O and reduced the production of aldehydes, albeit to different degrees. In all forms of ozonation, the main aldehyde products were formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, glyoxal, and methylglyoxal. HAO satisfactorily catalyzed the ozone oxidation of TCA and IPMP and effectively reduced the total aldehyde production during their oxidation. Catalyzed ozonation by AAO could not effectively reduce total aldehyde production during the oxidation of TCA and IPMP, which resulted in incomplete removal of T&O from water. Catalyzed ozonation by RAO provided the best results in removing MIB, TCA, and IPMP and reducing total aldehyde production.