Onsite Generation of Hypochlorite – Is It Cost Effective?

Abstract

INTRODUCTIONOn-site sodium hypochlorite generation has been a proven technology since the 1930's. This process uses salt and electric power to generate chlorine. Salt is dissolved in a brine solution then passed across electrodes powered by a low voltage current. This process produces a dilute hypochlorite of 0.8% in solution. On-site hypochlorite generation requires the construction of a brine tank, rectifier, electrolytic cells, a product tank, metering pumps and controls. Recent improvements in system reliability combined with new regulatory requirements are forcing water and wastewater utilities to reconsider their reliance on chlorine gas. This paper summarizes two economic analyses of disinfection system alternatives that have been recently conducted.In order to with comply risk management and process safety requirements, several water treatment facilities have installed onsite generation. It is receiving increased interest for use replacing chlorine gas at remote or satellite locations in potable water distribution systems and in the pre-chlorination of source water from reservoirs. Wastewater treatment facilities have, for the most part, not currently adopted the use of onsite generation of hypochlorite. Future applications, such as break-point chlorination for ammonia control, disinfection of backwash water, and chlorination of nitrifying bacteria, are very promising. BACKGROUND