Evoqua ETS UV Technology disinfects municipal wastewater before discharge to receiving waters. The ETS-UV™ system uses closed vessels, providing greater operator safety, a smaller footprint, easier maintenance, and lower life cycle costs. The UV chamber is constructed of 316L stainless steel and contains an automated wiper system that keeps the quartz tubes clean and the disinfection system operating at peak performance.

Two Types of UV Disinfection Systems Used for Wastewater Treatment

UV disinfection can be installed in an open channel or a closed vessel. The earliest types of UV systems were open channel systems which were racks of lamps installed in concrete channels. Maintaining a constant water level in open channel UV systems is essential for proper disinfection and operator safety. UV lamps must remain submerged during periods of low flow, and the water level should not get higher during periods of high flow so that the water depth above the lamps remains within tolerance for proper disinfection.

Level control is often achieved using a motorized weir gate mechanism that requires maintenance and is prone to blocking. Open channel systems often suffer from poor hydraulics, causing the incoming wastewater to flow along the top or bottom of the lamp banks, resulting in short-circuiting and inadequate disinfection.

Closed Vessel UV Systems are Rapidly Growing in Popularity:

• UV chambers are installed directly into the piping system.
• No need for a concrete channel, reducing installation costs.
• Safer for the operator because it eliminates exposure to UV light.
• Small footprint.
• Fewer lamps = less maintenance.
• It can be installed vertically or horizontally.
• Access hatch allows for easy bulb replacement.
• No requirement for a level control device downstream.

The Main Features of the Evoqua ETS Closed Vessel UV System:

• Stainless steel UV chamber.
• High-intensity UV lamps are housed inside the chamber and protected by quartz sleeves.
• Control Panel with all control components, including the user interface on the panel door.
• A motorized automatic sleeve cleaning wiper to clean lamp sleeves.
• UV Sensor monitors UV intensity inside the chamber and feeds readings back to the control panel.
• A temperature sensor to monitor reactor temperature protects operators and equipment if the water flow is interrupted unexpectedly.
• UV Sensor monitors UV intensity inside the chamber and feeds readings back to the control panel.
• Suitable for disinfection of wastewater, drinking water, water reuse, and industrial applications.

Disinfection Alternatives

The final step in the municipal wastewater treatment process is disinfection. Harmful viruses, bacteria, and other pathogens are inactivated or killed at this step. The two most common methods of disinfection in the U.S. are ultraviolet (UV) disinfection and chlorine.

Chlorine was once used in almost all wastewater treatment facilities and is still used at some. Chlorine destroys microorganisms by oxidizing the cellular material of microorganisms. It may be applied as chlorine gas, hypochlorite solutions, and other chlorine compounds.

Ultraviolet (UV) disinfection is the most widely used method for municipal wastewater disinfection. Inactivation by UV is a physical process rapidly affecting microorganisms as they pass by ultraviolet lamps submerged in the water. Within a few seconds of exposure, the DNA and RNA of the microorganisms are permanently disrupted, and they can no longer reproduce or cause infection. This ability has resulted in the widespread use of UV light as an environmentally friendly, chemical-free, and highly effective disinfection process at wastewater treatment facilities.

Both disinfection methods can effectively meet the disinfection requirements for treated wastewater; however, UV disinfection has significant advantages.

Advantages of UV Disinfection:

• UV disinfection is effective at inactivating most viruses, spores, and cysts.
• Inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia.
• Requires no storage, handling, or transportation of toxic or corrosive chemicals
• UV disinfection has a shorter contact time when compared with other disinfectants
• UV disinfection equipment requires less space than other methods.
• UV disinfection eliminates the need to generate, handle, transport, and store toxic/hazardous or corrosive chemicals.
• UV does not produce harmful byproducts.
• UV disinfection is safer for operators.

For the above reasons, ultraviolet disinfection is now a standard feature at most wastewater treatment plants. In addition, UV is also being adopted at drinking water facilities as a barrier against chlorine-tolerant parasites such as Cryptosporidium and Giardia.

Please call us to speak with a sales representative who will be glad to discuss equipment options and furnish specifications, drawings, and quotations.

by Mike Gillespie, P.E., President at Envirep

Envirep is the manufacturer’s representative for Evoqua ETS in Pennsylvania, New Jersey, Maryland, Delaware, Washington D.C., Virginia, and West Virginia.

For over 30 years, Envirep has been an industry leader serving the municipal and industrial water and wastewater market in eastern and central Pennsylvania, southern New Jersey, Maryland, Delaware, Washington D.C., and northern Virginia. We specialize in offering the highest quality products and aftermarket support to assist our customers.