Trichloroethene and tetrachloroethene in ground waters of Zagreb, Croatia.

At the end of 1986 the presence of chlorinated hydrocarbons was detected in the ground water of the industrial area of Zagreb, Croatia. Concentrations of trichloroethene and tetrachloroethene were close to or exceeded maximum admissible concentrations prescribed by the Public Health Regulations for drinking water (30 micrograms/l for trichloroethene and 10 micrograms/l for tetrachloroethene). The pumping-site situated within the area had been temporarily closed until a water-treatment plant based upon adsorption on activated carbon was built. Analysis of the results of adsorption of the investigated chlorinated hydrocarbons on activated carbon in granules confirmed a remarkably better adsorption of tetrachloroethene compared to trichloroethene. By constant monitoring and replacing of saturated carbon at the appropriate time, the concentrations of trichloroethene and tetrachloroethene in drinking water consumed by approx. 20% of the city population never exceeded maximum admissible concentrations in the course of 10 years.