DISINFECTION OF WATER BY MEANS OTHER THAN CHLORINE GAS: USE OF NaCl IN OPTIMIZATION OF ELECTROCHLORINATION

Abstract

Current, chloride and electrode material are the major parameters upon which the free chlorine generation and the disinfection efficiency depend. Due to the restraints in controlling the raw water parameters in the HYDROSIS plant the only parameter which could be changed in the electrochlorination process was the current. The water was the ground water supplied by the water department and was more or less same throughout the whole period when the study was carried out. The electrode material was also unknown and could not be changed due to the company policy. Majority of the studies carried out till now have dealt with changing the current in the HYDROSIS plant from 20A to 100A. Effect of the changing current on the free chlorine generation was carried out and a noticeable increase was observed. However a similar or a much larger effect is observed while varying the NaCl content by a small amount. The natural chloride content in the surface water in the Ganga Canal is very less ie in the range of 6-8mg/L. This was augmented by adding sodium chloride from 100mg/L to 300mg/L. A sharp increase in the conductivity and current is observed while keeping the same potential difference between the electrodes. From these studies it can be deduced that the same free chlorine generation can be achieved while keeping the current very low. The addition of NaCl can easily make up for the low chloride content or the absence of a steady power source.