Thesis (M. Sc.) - Asian Institute of Technology, 1995

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering.

This study was undertaken to investigate the possibility of applying kinetic model to predict residual free chlorine in water treatment, supply and distribution system. Hence, it became necessary to develop exact model to apply chlorine and simultaneously to reduce the formation of THM and yet to maintain the residual free chlorine level so that no contamination of water is possible in water supply and distribution system. The study involved observation of residual free chlorine by varying different parameter such as in terms of the absorbance level at the wave length of 260 nm, chlorine dose and temperature. Experimental measurements of residual free chlorine were carried out by the DPD colorimetric method. In this study two sample waters were collected from different water sources such as A.I. T. pond water infront of the Environmental Engineering Building and Bangkhen water treatment plant. For both of these waters the residual free chlorine was measured with the variation of absorbance value at the wave length of 260 nm, temperature and chlorine dose. In this study the kinetic model of residual free chlorine and diagram for determining the chlorine consumption by different active sites of humics were investigated by trial and error method to determine the effectiveness of applying both of these in actual application of chlorine. One important concept was developed from the experimental results. This concept is the determination of the amount of rapidly consumable chlorine. Also the THM formation for these two water sources were also investigated through the use of theoretical expression for the formation ofTHM. This THM formation for both of these water source were observed within the range of maximum contamination level of 100 og/l.