Deep UV Leds for Germicidal Water Treatment? Maybe...

 

Sorry it has been awhile since my last post. I was out of the office for awhile and came back to a massive pile of “this is THE top priority” projects to do. So here we go:

 

The NIST ATP Program which funds innovative R & D projects announced several LED-based awards for this year. Two of interest are the awards to Crystal IS, Inc. in NY and HexaTech, Inc. in NC. Both are working to develop efficient deep-UV LEDs. This is of particular interest because deep UV (normally referred to as UVC) is germicidal. That is to say, it can kill bacteria, certain viruses, and other contaminates. Traditionally UVC germicidal sterilizers and water purifiers use fluorescent or compact fluorescent type tubes (no phosphors are used so nothing is really fluorescing but they are the same type of lamp) mercury tubes to produce germicidal UVC at the 270nm (most effective wavelength) or 254nm (next most effective wavelength). While these traditional lamps are efficient and have a low cost to operate, they don’t like to function in cold environments and are bulky. In water purifiers that use them, they are typically encapsulated within a a chamber where the water can flow all around the tube to maximize exposure. When the lamp dies, you have to shutoff the water and dig the lamp out. If a company can produce UVC LEDs that have enough output for effective germicidal effect, it would mean that users of water purifiers and other remotely located UVC germicidal equipment would not have to change the light source nearly as often since LEDs have a typical lifetime of 20,000 hours and up although it will remain to be seen what the lifetime of a deep UV LED will be. There is also a huge potential for energy savings, particularly when multiple water purifiers are used. Municipal water treatment plants will uses 100′s or thousands of low-pressure mercury water purifiers (this number can be reduced to 10′s or 100′s if medium-pressure mercury purifiers are used) depending on the amount of water flow. Assuming the output of the LEDs is good enough and efficient enough, municipal water treatment facilities could see massive energy savings. Cost will be a big issue. right now low-pressure mercury lamps are fairly cheap, but LEDs will likely be quite expensive. They may come in at around the same price as medium-pressure lamps. Who knows. Even beyond the cost, municipal treatment plants will save massive amounts of cash on reduced maintenance costs by not having to tear down purifiers all the time to replace tubes. LEDs also function with no ill effects in cold environments so cold water rushing around them will not shorten their life. Also, fluorescent type mercury tubes don’t like to be turned off and on (it shortens their life) where LEDs don’t care. So if a plant operator needs to shut things down, it doesn’t matter. They can do it as many times as they want, it won’t shorten the LED lifecycle, although it may shorten theirs.

Anyrate, these projects are slated for a 3 year run so it will be awhile to see if anything becomes of them. I’m keeping my fingers crossed.

Here’s my last thought about deep UV LEDs: take a handful of deep UV LEDs and stick them in one of these multi-LED flashlights you see all over the place now and voila!You have an instant, portable spot tanning booth! Uh…maybe not.

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