Abstract

A study on chlorination of raw Yamuna River water is reported in this study. Samples were chlorinated with increasing doses of standard chlorine water and residual chlorine (Cl₂) was measured by Starch-Iodide method. For each sample, the chlorination curve (chlorine residual versus chlorine dose) was obtained. Curves showed the typical irregularity attributed to the formation and destruction of chloramines and transformation of toxic cyanobacteria (blue-green algae) by chlorine. It was observed that, after reactions with strong reductants and chloramines forming compounds, the remaining organic matter exerted a certain demand of chlorine. The evolutions of chlorination curves were studied. Till date, study on breakpoint chlorination revealed only single breakpoint but, in present study single breakpoints during chlorination of raw waters were not established in many cases. Double breakpoints have been reported in this study. The evolutions of different breakpoint curves might be attributed to formation and destruction of numerous chemical disinfection by-products (DBPs) and biological bacteria/alga, due to variant pollution conditions of raw water.

Key words: Ammonia, breakpoint chlorination, cyanobacteria, chlorine, pollution, nitrite.