Volatile organic compounds in the finished water of the water treatment plant in Thessaloniki, Greece

Chlorination has been the most widely used technology for the disinfection of drinking
water around the world. The main purpose for the disinfection of drinking water is to
protect it against microbial contamination in the distribution systems and to prevent or at
least control re-growth of microorganisms in the pipelines.
A major disadvantage of chlorination is the formation of a wide variety of halogenated
compounds from natural organic matter (Rook, 1974; Christman et al., 1983). Some of
these by-products, namely trihalomethanes, 1,2-dichloroethane, trichloro- and
tetrachloro-ethene have diverse negative effects on human health, including toxicological,
mutagenic and carcinogenic effects, as well as induction of congenital malformations and
retarded fetal growth (Boorman et al., 1999). Current regulations in Europe demand a
target of 100 μg l-1 for trihalomethanes (THMs), 3 μg l-1 for 1,2-dichloroethane, 10 μg l-1
for the sum of trichloro- and tetrachloroethene, 1 μg l-1 for benzene and include all the
prementioned compounds in the category of volatile organic compounds (VOCs).
Since September 2003, the city of Thessaloniki and its suburbs are partly supplied with
drinking water from the Thessaloniki Water Treatment Plant (TWTP), which takes raw
water from the river Aliakmonas. This study presents the regular monitoring results at the
TWTP during the period February 2004 – February 2005 for THMs and VOCs included in
the European guidelines. At the same time, parameters such as pH, temperature,
chlorine demand, total organic carbon (TOC) and contact time (tR) were monitored.