United Utilities installs on-site sodium hypochlorite generation systems
8 February 2006, News release from Severn Trent Services Ltd
March 2006 will mark two years successful operation of Severn Trent Services' ClorTec MCT installation at United Utilities' New Brighton site.
System Installed: ClorTec MCT-12
Installation Date: March 2004
Client: United Utilities
End User: United Utilities
United Utilities PLC was created from the merger of North West Water and Norweb in November 1995. Its principal activities are managing and operating the regulated electricity distribution, water and wastewater networks in North West England, a region with a population of around 7 million.
After evaluating treatment options, United Utilities decided to install an on-site sodium hypochlorite generating system capable of producing a chlorine equivalent, on-demand, to meet their disinfection needs.
The ClorTec on-site sodium hypochlorite generation system is approved for potable water within the UK and is compliant with ATEX requirements. The unit produces 5.4 Kg per day of chlorine equivalent using salt, water and electricity as its raw materials. The system operates by feeding softened water into a brine dissolver. The salt dissolves to form a brine solution, which is further diluted to the desired salt solution. The salt solution is then passed through the electrolytic cell(s), which apply a low voltage DC current to the brine to produce the sodium hypochlorite. The sodium hypochlorite is then safely stored in a day tank and, when it reaches the low-level set point, the system automatically restarts to replenish its supply. The unit typically requires operator visits once a week in order to keep salt levels topped up in the brine tank.
Since the ClorTec unit produces sodium hypochlorite on-demand, the technology alleviates the problem of chlorate by-product generation that typically results with the storage of bulk sodium hypochlorite. The ClorTec system also boasts clear acrylic cells which allow the proceeding reaction of salt, water and electricity to be visible and maintenance issues to be obvious. The split flow of brine to the cell ensures the economical, low chlorate production of 0.8% sodium hypochlorite solution. Since installation of the unit at New Brighton, only routine system maintenance has been required.
Stan Hill, Water Process Engineer at the United Utilities site, said "the ClorTec unit has many advantages over alternative disinfection techniques, and the low capital and operating expenditure were bonuses. Health and safety features are key to the design and Severn Trent Services' engineers visited the site prior to installation to carry out appropriate hazops."
For further information please email Severn Trent Services Ltd