As the fuss over chlorine safety continues, many are still trying to find acceptable, economical and environmentally safe alternatives to gaseous chlorine. I recently encountered an article in which sodium hypochlorite was generated on-site with a small environmental footprint and very little process change. The facility generates a 2-3 day supply at a time, and this store eliminates the need for a large storage area or an area that is a hazard containing chlorine cylinders. Even more impressive is the fact that the equipment to produce the sodium hypochlorite has a 2-3 return on investment. So not only does it eliminate transportation costs for chemical shipments, safety concerns associated with chlorine gas, chemical storage areas for the chlorine cylinders and totes of sodium hypochlorite, but it also is more environmentally friendly, as well as more efficient.
The process uses water, salt and electricity to produce a stable 0.8 percent free chlorine liquid sodium hypochlorite solution. The sodium hypochlorite generation is a fully automated packaged system that is easy to operate and maintain. The system is already piped, wired and tested. This type of system allows for a more control over the disinfection process, and also for greater security and is much safer. At this particular facility, the change was considered because the plant is in a residential area that is near a much-used city park. Safety was a very big concern during a rehabilitation project at the facility, and the gaseous chlorine issue was at the forefront of changes that the management wanted to address.
Many systems have been opposed to switching from chlorine gas due to increased cost concerns when converting to liquid usage. They also reviewed the fact that the lasting power of chlorine gas coupled with the desire to stick with the more traditional methods also contribute to the lack of change regarding this issue. As we go further in the 21st century, the water industry is starting to accept technological changes that enhance treatment more readily. As recent as a decade ago, some of these types of advances were rejected before they could be presented or the value of the processes was revealed. These greener technologies also can decrease the cost of insurance, material supply and shipping; decrease chlorine safety training hours and eliminate fears associated with the potential danger realized with the use of gaseous chlorine. As we find yet another viable technological advance as an alternative treatment method to gaseous chlorine, it remains to be seen if this trend will develop into the disinfection wave of the future or if gaseous chlorine will remain as the top form of water disinfectant.