ORIGINS AND IMPLICATIONS OF DRINKING WATER ODOURS IN BOVILLA RESERVOIR

The relationship between commonly measured limnological parameters and odours was examined in Bovilla reservoir used as source for drinking water. Since 2001 the Bovilla drinking water treatment plant, has been facing taste and odor problems usually during fall and winter time up to early spring. The nuisance, often quite severe, could only be removed by using advanced and costly treatments through adsorption on activated carbon.It was found that there is an obvious relation between the unpleasant smell and taste periods and the stratification situation: smell starts when stratification begins to weaken, and it ends after the overturn when stratification is again establishing. Maximum values of turbidity and rainfall, a gradual increase of the pH and maximum values of phosphate and iron concentrations have been observed during the smell and taste periods. Odour analysis was conducted using gas chromatography ion-trap mass spectrometry. It seems that neither geosmin nor 2-MIB were definitively present in the water at the sampling time, but an astonishing number of various VOCs were present included lower alcohols and aldehydes,borneol,butyl-4-methylcyclopentene,camphor,carvone,norpinon,pinocarvone, propyl¬cyclohexanone, alpha-terpineol, verbenon and mono- and sesquiterpenes. It was found that Carvone may be a dominating compound causing the smell.