Jan 02, 2002

What are the Advantages of On-Site Sodium Hypochlorite Generation vs. Chlorine Gas?

The City of Albuquerque depends entirely on groundwater from 93 deep aquifer wells to supply water to over 400,000 residents. Traditionally, reservoirs would receive water from well fields and use chlorine gas from 150-lb. cylinders for disinfection purposes. The inherent hazards of handling chlorine gas, coupled with the increasing regulations of its use, prompted the Albuquerque Water Utility Division (AWUD) to set up a pilot installation of a gas chlorination system that would meet the new regulations. Gas chlorination proved to be too costly leading to the examination of viable alternative disinfection technologies.

AWUD examined the capital, maintenance, and chemical costs of alternate technologies such as the purchasing of bulk sodium hypochlorite and on-site sodium hypochlorite generation. After careful evaluation, AWUD chose the Severn Trent Services ClorTec on-site sodium hypochlorite generating system.

Superintendent of Plant Operations for the AWUD Randy Walsh recognized the operating advantages of an on-site generation system verse the traditional gas chlorination systems. Some of the operational benefits of the system include eliminating the handling and storage of hazardous materials, avoiding dependency on chemical suppliers, and reduction of disinfection by-products (DBPs). Moreover, the overall costs of on-site generation systems are lower versus conventional technologies. The ClorTec system specifically uses salt, water, and electricity as its only raw materials to produce hypochlorite on-site, as it is needed.

As of March 2001, experience to date with the 11 of 28 stations installed has been successful in consistently maintaining the chlorine residuals in the treated water in storage and distribution at the desired level.