The screening of disinfection by-products in large and small water systems in Greece

In this paper, we investigated the presence of twenty four disinfection by-products (DBPs) including four trihalomethanes, six haloacetonitriles, three haloketones, chloral hydrate, chloropicrin and nine haloacetic acids, in drinking water treatment plants (WTPs) and their distribution systems of Athens for a period of more than ten years (1993-2005). The detection of trihalomethanes was also conducted in two smaller water distribution systems in Greece for a period of six months to one year to evaluate the effect of different quality of raw water on the formation of these compounds. In all cases, the determination of DBPs was conducted monthly. The concentrations of DBPs were determined by a gas chromatography method, which included sample preparation with liquid-liquid extraction for volatile DBPs and acidic methanol esterification for haloacetic acids. The DBPs concentrations detected varied depending on the raw water qualities, in the WTPs after the point of prechlorination and in the distribution system, while their presence was not noticed in raw water. In any case, with little exceptions, the trihalomethanes and haloacetic acids concentrations were lower than the maximum contaminant level set by European Community and USA Environmental Protection Agency.