High Flow Rate (4000 gpm) Water Disinfection Using UV Treatment

Ultraviolet Sciences Inc. (UVSI) has introduced a new, high volume, disinfection water treatment bank, Model No: TB-UVS438S-500-8. This new water skid is capable of disinfecting water at flow rates up to 4000 gpm.

Ultraviolet light is an effective disinfection tool. Ultraviolet light disinfects by disrupting the DNA or RNA structures of microorganisms. The disruption prevents microorganisms from replicating, thereby rendering them inactive and unable to cause infection. The primary mechanism of inactivation by UV is the creation of Pyrimidine Dimers which are bonds formed between adjacent pairs of thymine or cytosine pyrimidines on the same DNA or RNA strand.

The 253.7 nm peak output level of low-pressure UV lamps is relevant for disinfection because it is very close to the 260 nm peak where DNA and RNA experience maximum UV absorption. Because the 253.7 nm wavelength is extremely effective for disinfection, ultraviolet lamps that are installed for disinfecting water often use quartz envelopes and sleeves designed to "block" the 185 nm ultraviolet output and prevent the creation of ozone.

One of the primary benefits of UV for disinfection is that it does not contain nor create any residuals, or byproducts, such as occur with chemical methods of purification. In fact, UV is sometimes used to remove residuals, and disinfection by-products, such as chlorine, peroxide, ozone, and trihalomethanes, that result from other purification processes.

Different species of microorganisms require varying levels of UV exposure, but nearly all can be effectively inactivated with a fluence level of 30 mJ/cm2. With fluence levels in this range, UV systems are able to achieve a 4-log reduction for most microorganisms. This is equivalent to a 99.99% reduction. Ultraviolet disinfection of water is extremely effective when the water being treated is highly transmissive. With lower levels of transmittance it may be necessary to filter prior to UV treatment or use additional UV lamps to ensure sufficient levels of treatment.

Ultraviolet Sciences Inc new, high volume (4000 gpm), disinfection water treatment bank consists of eight of the highly efficient and ultra compact UVS438S-500 UV treatment chambers. Its modular "rack and stack" configuration allows for full access to each UV treatment chamber for maintenance operations. A "Hot Swap" option allows for equipment maintenance during operation. The individual UVS438S-500 treatment chambers use just two low pressure, high intensity, Amalgam lamps. These lamps deliver the crucial 253.7 nm wavelength necessary for microbial disinfection.

Flexibility defines our new high volume disinfection water skid. The modular nature accommodates numerous types of interface, which also unique to the industry. The individual UV treatment chambers can be connected in series for maximum disinfection, or in parallel to increase the system flow rate. And only two Control Units, (CU) are required per water treatment skid. Each CU operates up to four separate treatment chambers.

Maintenance is simple. The open frame construction allows easy access to the individual treatment chambers. The UV lamp length is only 38 inches. Changing a lamp is simple, requiring no tools, and only requires 42 inches of clear work area.