Taste and odour problems generated in distribution systems: a case study on the formation of 2,4,6-trichloroanisole

Abstract

A taste and odour (T&O) episode in a Swiss town, where consumers complained about a musty odour in their drinking water, was investigated. The application of a combined organoleptic and instrumental method for T&O anaiysis allowed the identification of 2,4,â-trichloroanisole (TCA), with an odour threshold of 30pgl"\ in the drinking water in concentrations of up to 24ngl"''.The absence of this compound in the raw water and after treatment showed that it was formed in the distribution system. Experiments conducted in the iaboratory showed that trichlorophenol as a potential precursor or chlorine as residual disinfectant played a key role in the formation of TCA, which was only formed in the presence of biofiims. Based on these results, appropriate counter-measures, such as water distribution without residual chiorine and maintenance of househoid particie fiiters, are suggested to mitigate this T&O probiem.

Chlorination of Phenols Revisited: Unexpected Formation of α,β-Unsaturated C4-Dicarbonyl Ring Cleavage Products

“…Additional research is needed to quantify the concentrations of these C 4 -dicarbonyl compounds after water is disinfected with chlorine in drinking water treatment plants and in distribution systems. Phenol, chlorophenols, and bromophenols occur in source waters and in finished drinking water at concentrations as high as 10 μg L –1 . ,,,− On the basis of the results from this study, concentrations of α,β-unsaturated dialdehydes in a similar concentration range (i.e., several micrograms per liter) could occur when chlorine is employed for disinfection and to mitigate taste and odor issues associated with the presence of chlorophenols. The concentrations of these compounds will be affected by the chlorine dose and the presence of organic and inorganic compounds that can react with dicarbonyls (e.g., nucleophilic compounds like proteins associated with biofilms).…”

“…Phenol, chlorophenols and bromophenols occur in source waters and in finished drinking water at concentrations as high as 10 µg L -1 . 17,21,27,[92][93][94] On the basis of results from this study, concentrations of -unsaturated dialdehydes in a similar concentration range (i.e., several micrograms per liter) could occur when chlorine is employed for disinfection and to mitigate taste and odor issues associated with the presence of chlorophenols. The concentrations of these compounds will be affected by chlorine dose and the presence of organic and inorganic compounds that can react with dicarbonyls (e.g., nucleophilic compounds like proteins associated with biofilms).Additional research is needed on the biostability of -unsaturated dicarbonyl compounds, their formation relative to other DBPs and the relevance of phenolic groups --present in NOM as precursors of -unsaturated dicarbonyl compounds formed during drinking water chlorination.…”

Water Analysis: Emerging Contaminants and Current Issues

“…Using this method, they also proposed structures for several new brominated DBPs in simulated drinking water. Finally, Peter and von Gunten used SPME-GC/MS/olfactory detection to identify 2,4,6-trichloroanisole, following a taste and odor episode in a drinking water system in Switzerland . This DBP has a very low odor threshold of 30 pg/L, and it was found up to 24 ng/L in drinking water but only in distribution systems and not in the raw source waters or finished waters from the plant.…”

Novel Water Treatment Processes Based on Hybrid Membrane-Ozonation Systems: A Novel Ceramic Membrane Contactor for Bubbleless Ozonation of Emerging Micropollutants

“…(i) taste and odor control [30]: compounds that cause taste and odor problems in surface and groundwater are organic compounds produced by algal blooms and bacteria (mainly geosmin and 2-methylisoborneol (MIB)), inorganic compounds and mercaptans (organic sulfides), iron, and manganese;…”