Occurrence and removal of 10 odorous compounds in drinking water by different treatment processes

This study investigated the prevalence of ten odorous compounds (2-methylisoborneol, trans-1,10-dimethyl-trans-9-decalol, isophorone, 2,4,6-trichloroanisole, 2,3,6-trichloroanisole, 2,3,4-trichloroanisole, β-cyclocitral, β-ionone, 2-isobutyl-3-methyoxypyrazine, and 2-isopropyl-3-methoxypyrazine) in raw drinking water, as well as their removal by traditional processes, advanced oxidation processes, ultrafiltration, and nanofiltration processes, with the use of an ultrahigh-resolution Orbitrap. The most abundant odorous compounds referred to 2-methylisoborneol and trans-1,10-dimethyl-trans-9-decalol with maximal concentrations of 1.6 ng/L and 0.09 ng/L after treatment by traditional processes respectively, and their maximal concentration was 2.05 ng/L and lower than the detection limit after treatment by advanced oxidation processes, while the raw drinking water of the mentioned two processes was different. The high concentration of isophorone in water treated by traditional process, advanced oxidation process, and membrane process was also ascertained. On the whole, the removal rate of membrane process is the maximal for all odorous compounds except for 2,3,6-trichloroanisole, followed by the advanced oxidation process as well as the traditional process. Eight odorous compounds identified in raw water were preserved after traditional treatment, while five compounds were preserved after the advanced oxidation treatment. The combined ultrafiltration and nanofiltration with pre-flocculation was more effective than either the advanced oxidation process or the traditional treating process in removing odorous compounds, and over 90% of all the odorous compounds were removed. Further investigation is required to facilitate the removal of odorous compounds from drinking water by the incorporation of ultrafiltration and nanofiltration units based on current drinking water treatments.