Break point chlorination

Break-point Chlorination

• When chlorine is added to water, it reacts with organic and inorganic matter. Some portion of chlorine remains as residual chlorine. This part of chlorine is weak in disinfecting action. If the chlorine dosage is increased, the combined available residual chlorine is increased.
• The increased concentration of chlorine enables the oxidation of compounds and along with newly formed substances.
• If a graph is plotted with chlorine dosage on 'X-axis' and residual chlorine on 'Y-axis' a curve is obtained as shown in the figure below.
• A study of the curve reveals that residual chlorine increases in the beginning but after a point, it suddenly drops and then increases again.

• The point at which the residual chlorine starts increasing again is called breakpoint chlorination.
• After this point chlorine added remains as free residual chlorine and the curve becomes a