Another application of UV in Water Treatment Industry:
Some water treatment applications, Ozone gas is injected into the water stream to oxidize trace organics or to disinfect the piping and distribution system, but residual ozone often remains at Point-of-Use P.O.U. In some application, there is no allowance for dissolved ozone at Point-of-Use. The most efficient method to remove residual ozone without chemical add by using UV 254 nm as Post treatment.
Although UV 254 nm able to destruct ozone, but it requires much more energy than optimum UV dosage for germicidal application, Therefore you have to reduce common used germicidal flow rate by 60% and design flow in a double pass to achieve effective Ozone Destruction.
UV energy at 254 nm wave length able to catalyze dissolved ozone gas back into oxygen gas.
OZONE DESTRUCTION AT WATER FLOW RATE
Germicidal flow rate application serve for water flow rate @ UV dosage 40 mJ/cm2
Power input; Watts
|UV intensity; Microwatt/cm2 @1 inch|
Number of Lamp / Ballast / Transparent plastic cap
Water Inlet and Outlet port
UV Reactor Chamber ; Inch
UV FOR CHLORINE/CHLORAMINE DESTRUCTION:
Chlorine and chloramine are used extensively for water disinfection, these compounds, and related byproducts, such as trihalomethanes (THM’s), are often present in water supplies. These compounds must be removed because they are potential health hazards, and affect the taste of consumable products, such as flavored beverages and bottled water. Removal is also necessary because chlorine and chloramine based compounds can significantly increase the operational/maintenance costs for purification equipment, such as ion-exchange beds and reverse osmosis (RO) membranes, all used for ultrapure water processing.
UV become more popular to destroy chlorine/chloramine compounds as the performance of UV lamps. The mechanism which enables UV to destroy chlorine/chloramine compounds is dissociation. The UV energy “breaks” the molecular bonds of the compounds & reduce them to their basic elements. These basic elements will either combine with others to form benign compounds, or they can be subsequently removed in a downstream purification process.
Traditional methods to remove chlorine/chloramine are Granular Activated Carbon (GAC) , or chemical injection with sodium metabisulfite. Sodium metabisulfite can introduce undesirable byproducts into the water supply, it also creates conditions for microbial growth in RO membranes. Sodium metabisulfite is also a potential health hazard that requires protected the storage and careful handling.
Activated carbon beds used for chlorine/chloramine removal are susceptible to microbial proliferation, and they are vulnerable to “break-through”. It is necessary to inspect, clean, and replace activated carbon beds regularly, which requires both expenses & time in manufacturing lines.
UV treatment prior to activated carbon beds and RO membranes will reduce overall operating costs by increasing the time between cleaning cycles and extending the life of both GAC beds and RO membranes. UV also provides additional benefits of disinfection and TOC reduction, without affecting taste , without difficulty to remove residuals.