ABSTRACT
ABSTRACT: Water quality per se directly affects public and environmental health. If the water supplied is not adequate for human consumption it can cause serious water born epidemic. High levels of microorganisms in raw water in developing countries, especially faecal bacteria, leads water companies to increase gaseous chlorine concentration in the treatment system in order to guarantee the quality of the final product, that is, potable water. When both residual chlorine and humic substance (DOC) concentrations are available in water, a secondary reaction will occur, resulting in the formation of trihalomethane (THM). Thus, it is important to assess and evaluate the presence of certain substances and organisms in water in order to verify its quality for consumption, especially related to THM. This research was based on the fact that, in January 2001, the water supplied in Curitiba, Brazil, was allegedly not presenting the quality established by a federal regulation (Potable Water Regulation Act – FUNASA n° 1469/00) with respect to residual chlorine and THM. In such a context, a monitoring programme was established to assess the quality of the water supplied as a consequence of the presence of excessive chlorine concentration. As part of the monitoring plan some physico-chemical and microbiological parameters in both raw and treated water were determined, such as: total organic carbon, pH, colour, turbidity, total and faecal bacteria, total THM, and residual chlorine. The results of this research reflect the first serious methodological attempt to evaluate water quality response of Curitiba system for THM formation. Moreover, the basis for the development of a mathematical model to evaluate and predict THM concentration in the above mentioned water supply system will be developed.
