AWWA ACE58243

In the Le Pecq service area (Paris suburb), medicinal taste and odor problems have been occasionally observed. The cause seems to be due to the slow formation of brominated phenols that occurs upon chlorination of phenol contamination in the groundwater that contains bromide. The objectives of this project were: to identify the off-flavor causing compounds; to characterize conditions that lead to medicinal taste and odor during the water treatment process; and, to provide recommendations to prevent bad taste formation by optimizing the groundwater management and treatment operating conditions. A global approach was implemented that included: extensive taste testing of finished waters leaving the different water treatment plants (TWP) to identify medicinal taste occurrence (more than 1500 taste testing in 2001); an extensive sampling program of both ground and finished waters to identify and quantify phenolic compounds (more than 300 samples collected); modeling of the groundwater pumping facility to characterize origins and residence time of the water entering the different treatment plants; building of a database containing information relating to resources, treatment operating conditions and T&O occurrences to establish statistical links; and, a lab-scale study to investigate the contribution of different water quality parameters on medicinal taste formation. The article describes the methodology applied to identify the off-flavor causing compounds, to characterize conditions that lead to medicinal taste and odor during the water treatment process in order to provide recommendations to prevent bad taste formation by optimizing the groundwater management and treatment operating conditions. Includes 6 references, tables, figures.