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Ultraviolet (UV) FAQ

What is Ultraviolet (UV) light?

Ultraviolet light is a natural component of sunlight. Ultraviolet light are electromagnetic wavelengths of 200 – 400 nanometres (nm). Ultraviolet (UV) energy has the unique ability to destroy harmful microorganisms by disrupting their genetic information (DNA), rendering them unable to reproduce. The nature of UV light, makes it the most efficient, economical and environmentally safe method of water and wastewater disinfection among all current offerings in the market.

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Is Ultraviolet (UV) light for water and wastewater disinfection a validated technology?

The disinfecting effect of ultraviolet rays has been known since 1878, when sunlight’s bacterial effect was discovered. In 1910 the world saw the first attempt to use UV irradiation for disinfection of water. Today, UV is applied in more than 20% of all municipal wastewater treatment and the number is steadily increasing.

How much Ultraviolet (UV) light is needed for water and wastewater disinfection?

Organisms in water require a minimum ultraviolet light dose before the organism inactivate. This UV dosage depends on the ultraviolet light intensity, exposure time and exposed area. It is commonly calculated in µWs/cm2. High log reductions in the viable organism counts demand larger UV dosages.

What is the difference between water and wastewater disinfection with chlorine versus ultraviolet (UV) light?

Where chlorination utilizes a chemical reaction to destroy, or burn away the genetic material of organisms, UV utilizes the rays from special mercury vapor lamps as catalyst to replicate the natural photosynthesis process. This process paralyzes the microorganisms and consequently leads to their death. This fully natural treatment process is increasingly gaining foothold in the municipal wastewater market and thousands of municipalities have converted from chlorine to UV light for disinfection over the last decade.

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How are Enaqua’s ultraviolet (UV) disinfection systems for water and wastewater disinfection different from alternative UV offerings in the market?

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How is the cooling system on Enaqua’s UV disinfection systems designed?

All of Enaqua’s UV disinfection systems are air cooled by heat exchangers, fans and/or blowers depending on the design. Systems larger than ~3.5 MGD, and/or installed in-channel will have air to water cooling systems and air cooling of electronics. Compared to the submerged lamps in Contact UV systems, where the lamps temperature cannot be controlled and heat is released directly in the water, Enaqua’s Non-Contact UV systems can benefit from temperature control of the lamps. In Enaqua’s Non-Contact UV systems lamps can run at peak efficiency at around 42ºC.

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WHAT IS THE CALCULATED OPERATIONAL ENERGY CONSUMPTION OF ENAQUA’S NON-CONTACT UV SYSTEM?

In deviation from industry standards, Enaqua’s operating power calculations include all cooling and control of cooling. This cost is usually not included, or split into other specification sections. For example; the power for the compressor to operate the wipers in the sleeves or air conditioners for cooling of ballasts is usually not included in competitive power calculations, despite the fact that it is required for the proper operation and maintenance of a UV system.

WHY DOES ENAQUA’S NON-CONTACT UV SYSTEMS NOT REQUIRE A FIXED WATER LEVEL?

Enaqua’s UV disinfection systems are designed so that no level controls and weirs are needed to maintain effluent water level – in other words we can utilize free discharge minimizing plant hydraulic design issues. We can design with or without free discharge in regards to what provides our customers with the best solution.

WHAT HAPPENS IF QUARTZ SLEEVES OR UV LAMPS BREAKS?

In typical Contact UV systems, if a lamp or quartz sleeve were to break they would enter the water stream. However, Enaqua’s Non-Contact UV systems are designed such that there is no possibility of glass or mercury entering the water stream. In Enaqua’s systems any broken glass of the lamp fall into the bottom of the stainless steel chamber and is never in contact with the water.

Where can I read more about the regulations regarding water disinfection requirements?

Many governmental regulations have been established in recent years for the protection of the environment. The Clean Water Act and the Resource Conservation and Recovery Act are among the most significant.