Non-Contact™ UV Disinfection

AFP™ Non-Contact Disinfection systems by ENAQUA are diametrically opposed in design to every other municipal UV disinfection system on the market. Unlike traditional systems, the ENAQUA systems do not have their UV lamps surrounded by fragile and fouling-prone quartz sleeves. AFP™ Non-Contact systems have their water flowing through the inside of Activated Fluoropolymer™ tubes, with the lamps on the outside – always dry. In traditional quartz UV systems, water flows through an open channel with the UV lamps submerged within the channel. AFP™ Non-Contact systems feature banks of “dry” UV lamps surrounding water conveying tubes, such that each tube gets exposed to ultraviolet light from all sides. This eliminates the need to interrupt or remove any hydraulic seals during any lamp maintenance. In fact, the AFP™ tubes need never be replaced or removed from the system.

AFP™ Non-Contact Disinfection systems do not flow water in a typical “channel”. The flow takes place in a series of circular tubes, thus having a very smooth internal surface. Also, unlike traditional channels, they are naturally turbulent and plug flow in nature. This design makes it easy to predict and monitor the systems performance as well as provide for scale up - all designs are modular.

The UV lamps in ENAQUA’s systems are outside the flow of water. This allows for the use of conventional Low Pressure High Output lamps instead of the proprietary and expensive “Amalgam ”lamps used in traditional quartz-based UV systems.

The modularity and simple design of the AFP™ Non-Contact Systems enable simple scale up from as small as 0.028 MGD (1.26 l/s) to as high as 31.68 MGD (120,000 m3/day) in a single reactor with little or no flow variation between the tubes. This feature, unlike traditional channel based systems, make ENAQUA’s AFP™ Non-Contact systems unique and without peer in the industry. The basic system designs are also the same whether installed in a channel or as an in-line piped system.

Uniform UV Exposure

All of ENAQUA's ENLIGHT™ systems feature full liquid flow through tubes, surrounded by UV lamps for complete exposure by UV light. This method is the most effective means of disinfection when compared to immersed lamps in water. Simply put, the volume of water closest the UV lamps is maximized in the AFP Non-Contact systems as compared to the quartz based UV systems. The closer the water is to the lamp, the greater the UV intensity and thus the better the disinfection. As the illustration shows, there are no “red” areas of concern in the ENAQUA design. These “red” areas represent water that is greater than 3 cm from the UV lamp. In the ENAQUA design, 56% of the water is within 1 cm of the most intense UV light, and another 33% is within 2 cm of the UV lamp. So, a total of 89% is within the first two zones. In a quartz system, only 22% in within 1 cm of the most intense UV light, and only 33% is within 2 cm of the UV lamp – only 55% within the first two zones. The quartz systems in fact have 9% of the water underexposed as it is over 3 cm away from the UV light.

Turbulent vs. Laminar Flow

In ENAQUA’s AFP Non-Contact systems, all the water to be disinfected flows through proprietary Activated Fluoropolymer (AFP840) tubes. Banks of UV lamps surround the tubes such that each tube gets exposed to ultraviolet light from all sides. This design is extremely efficient in the utilization of UV energy. Furthermore, the flow takes place in tubes with a very low coefficient of friction. The flow is uniform, plug flow in nature and calculating the turbulence (Reynolds Number) is very simple –unlike in a quartz system which can be very difficult. The uniform flow characteristics allow the performance of the AFP Non-Contact system to be accurately predicted.

True “plug” flow means that all the water that enters the tube, goes through the tube at virtually the same rate and exits the tube at or near uniform velocity.

In a quartz UV system, the channel causes variations in flow rate and the flow is not uniform. This causes variable residence times within a given system and lower UV dose in parts of the system affecting performance as shown in the channel flow diagram.