Web Exclusive - April 2012
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Cleaning the Water, Clearing the Air

How UV Water Treatment Improves Water and Air Quality

By Jeff Boynton

5 Main Chloramine Removal Options

If you are looking to improve the air quality of swimming pools, especially indoor swimming pools, you have five main methods to reduce and remove chloramines:

1. Non-chlorine shock with mono per sulfate-based oxidizers
These products are very expensive compared with chlorine, but are strong oxidizing agents to break down chloramines when reaching breakpoint oxidation. The use of non-chlorine shock will require more intense water chemistry monitoring. And, it does add more chemicals to the water.

2. Hyper-chlorination
As a part of regular maintenance, a pool is shocked periodically to remove organic compounds, remove chloramines and free up the available chlorine to allow it to sanitize the pool. However, this also binds up the free chlorine and keeps it from performing its sanitizing function if not used in proper amounts. And, it is adding more chemicals to the water.

3. Adding ozone to the water
Ozone as a secondary oxidizer destroys ammonia and nitrogen, preventing the formation of chloramines. As a disinfectant, this technique requires a large unit to disinfect by injecting the ozone into a side stream (about 10 percent up to 25 percent of the water) and then returns it into the full flow.

4. Drain & refill water
This results in refilling millions of gallons of fresh water, which is wasteful, but also presents the new problem of having to constantly monitor the pH, temperature adjustment and alkalinity of the water—not to mention the difficulty of disposing of the water containing unacceptable levels of chemicals into sewer systems.

5. Adding a UV system
Remember that UV-C doesn't change the pH, turbidity or alkalinity of the treated water. Thus, the two main benefits to UV over the other options are that: 1) UV damages DNA/RNA at a wavelength of 254 nm so water is sanitized, and 2) studies show that both medium and low pressure bulbs decrease chloramine levels down to ranges acceptable to health organization guidelines.

Choosing the right UV System

Not all UV is the same. It is important to determine the correct sizing of the UV unit for the type of pool and its use. Water flow is a major factor in determining the size of the unit. Also, is the pool use more commercial or more residential, and what type of bather load needs to be treated? Indoor or outdoor?

Basically there are two different types of UV lamps: a low-pressure high-output lamp, which emits UV rays only at 254 nm, and a medium-pressure lamp which emits UV rays between 200 to 600 nm.

Generally low-pressure UV lamps may be better suited for residential applications, while medium-pressure models typically are designed for large commercial installations. The distinction can be chalked up to cost, flow requirements and the ability to destroy chloramines.

Due to their large light spectral (200 to 600 nm), medium-pressure lamps more effectively reduce the health problems caused by nitrogen trichloride (chloramines).

In sum, the facility usage, type of pool and bathing loads are all to be considered. For example, the needs for an indoor Olympic-sized pool with a heavy bather load will substantially differ from an outdoor medium-sized pool at a hotel. The UV technology needs to fit the environment and should be affordable so that the facility can take advantage of the benefits of UV light technology.

Key Things to Consider:

Wattage: Compare the wattage needed to attain good flow treatment. The wattage consumption between different products varies. Also, you will save more with a system that has an electric ballast, which prolongs the life of the UV bulb and uses less energy.

Spare Parts/Maintenance: Ask about spare parts pricing, which varies by manufacturer. And be sure to ask about required maintenance costs. Consider the number of bulbs in the system. Some UV systems may require substantial maintenance and require servicing for warranty program.

Cost/Payback: Notwithstanding the obvious health benefits of UV water treatment using fewer chemicals and providing a safer bathing environment, many times a UV system will pay for itself in comparison to "traditional" methods of sanitation. Depending on many variables including water quality, bather load, the facility's filter system and installation, the return on investment could be less than one year, all while providing better air and water quality. Plus you'll be able to say you are lowering your carbon and water footprint on a planet—which is good for you and planet earth!