Chlorine gas has traditionally been used for wastewater disinfection for many years. Sodium Hypochlorite (liquid bleach) is an alternative to chlorine gas; however, it is more costly and has the same environmental concerns. UV disinfection can easily be retrofitted into an existing chlorine contact tank and has significant benefits compared to chlorine disinfection.
The increasing concerns about the hazards of chlorine disinfection to the public, the operators and the environment have dramatically increased the cost of chlorination and dechlorination chemicals along with the administrative efforts required to meet safety regulations. As a result, UV disinfection has increasingly become the choice for wastewater disinfection due to some significant advantages over chlorine-based disinfection. Specifically, UV has been proven effective in various types of effluent, requires less maintenance, and is cost-effective.
UV has been used to disinfect various types of effluent from low-quality primary effluent to high-quality tertiary effluent. Over 6,000 wastewater treatment plants have installed TrojanUV systems, some of which are disinfecting even the most challenging effluents like primary effluent and combined sewer overflows.
Advancements in UV technology over the years have significantly reduced the amount of maintenance required by operations staff. Advances such as the automatic ActiClean chemical/mechanical cleaning system eliminates the need to manually clean lamp quartz sleeves. The development of more efficient, longer-life and high-output lamps results in fewer lamps to service and maintain as well as reduces the required footprint. For example, the TrojanUVSigna has been designed with TrojanUV Solo Lamp Technology to make chlorine conversion easier.
Because no hazardous chemicals are required for UV disinfection, the cost of operating a UV system is significantly lower than chlorine disinfection. In many cases, the installation of UV is a more cost-effective, long-term solution due to the high cost of safety requirements and chemicals for chlorine disinfection (e.g. sodium hypochlorite disinfection).
UV disinfection also has the added benefits of not being affected by temperature or pH of the effluent. UV does not create any disinfection byproducts and can disinfect chlorine-resistant microorganisms like Cryptosporidium and Giardia. The carbon footprint and environmental impact of a UV disinfection system has been shown to be lower than chlorine disinfection since UV disinfection is a physical process that eliminates the need for hazardous chemicals.