UV Water Treatment Provides Safe and Effective Alternative to Chlorine Disinfection

UV Water Treatment Provides Safe and Effective Alternative to Chlorine Disinfection

Water treatment operations, both large and small, are turning to ultraviolet radiation (UV) as an alternative to reduce or eliminate the use of chlorine for disinfection. Chlorine is a commonly used and effective disinfectant. Operators at wastewater, drinking water, environmental remediation facilities, and even homeowners with backyard swimming pools use chlorine to protect against disease-causing organisms.

However, there are some microbial pathogens, such as Cryptosporidium and Giardia, that are resistant to chlorine disinfectant. Plus, adding chlorine and other chemicals to treat water is an expensive endeavor, and the process adds safety concerns. The EPA has also set limitations on the amount of residual chlorine and disinfection byproducts created by chlorine treatment in drinking water and wastewater effluent. All of these factors are leading system operators to consider UV treatment.

How UV disinfection works 

We receive UV radiation from the sun, but the wavelength of UV light that destroys organisms is largely blocked by the Earth’s atmosphere. In a water treatment application, UV disinfection is applied in a pressurized closed vessel (usually a stainless-steel tube) by amalgam lamps. UV light doesn’t kill pathogens. It penetrates an organism’s cell wall, disrupts the cell’s DNA, and destroys its ability to reproduce. If the cell can’t reproduce, it’s no longer harmful to the human body.

Compliance with EPA’s LT2 Rule 

Adding a UV disinfection system will enable water treatment facilities to comply with the EPA’s Long Term 2 Enhanced Surface Water Treatment Rule (LT2 rule), which requires additional inactivation of Cryptosporidium and takes effect in 2014.

Unfiltered water systems, like the City of Brewer in Maine, did not have Cryptosporidium removal requirements prior to the LT2 rule. Brewer is working with Woodard & Curran to implement a UV disinfection system to provide 3-log inactivation of Cryptosporidum along with ozone to provide primary Giardia and virus disinfection and chloramines to provide system residual treatment.

A versatile technology 

Our experience working with UV treatment systems as both design engineers and plant operators is that it’s a very effective and versatile system. At the University of Connecticut’s Storrs Campus, Woodard & Curran is operating a new water reclamation facility that receives treated wastewater from the university’s water pollution control facility. The wastewater is screened, then filtered by one of three microfiltration trains, and finally disinfected by UV light. This reclaimed water is then available for non-potable use. UConn plans to use the reclaimed water primarily at their Central Utilities Plant in its cooling tower, chilled water system, and boilers.

The benefits are clear 

The use of UV systems for disinfection is becoming much more common. UV provides chemical-free disinfection, and it is considerably more efficient at the inactivation of Cryptosporidium than ozone or chlorine.

Retrofitting an existing system depends on a number of factors—in particular, the available space for installation and future maintenance. UV systems may not be right for every operation, but it’s clear that UV treatment works.

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Senior Client Manager
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