Blue LED Water Purification

They consume very little power for the amount of light that they give off, but are blue light-emitting diodes or LED’s produce enough ultraviolet or UV radiation to kill water-borne bacteria to make water safe to drink?


By: Ringo Bones


I was skeptical at first given my first-hand experience and working knowledge of light-emitting diodes. But a research scientist at the Berlin Institute of Technology had recently claimed that he had developed a set-up to purify water – i.e. killing water-borne bacteria via ultraviolet radiation – using just an array of blue light-emitting diodes. If this works, it would start a new revolution on how we obtain safe drinking water. Given that blue LED’s are hundreds of times – even more – efficient than the mercury-vapor lamps currently in use to produce ultraviolet rays to kill water-borne bacteria and other pathogens as a way of making water safe to drink.

The blue LED water purification concept was aired on October 6, 2008 in a DW-TV science program titled Tomorrow-Today. Michael Kneissl of the Berlin Institute of Technology has demonstrated his blue LED water purification prototype set-up with claims that the blue light-emitting diode array produces enough UV radiation to “zap” harmful water-borne bacteria. If this is true, then Michael Kneissl probably made himself a Nobel Prize worthy concept given that mercury-vapor UV lamps currently used in this type of water purification are very power hungry in comparison to the (claimed off the shelf) blue light-emitting diodes that he used.

Theoretically, light-emitting diodes can last thousands of years – up to 150,00 years - if used well below their current limit ratings. If the Berlin Institute of Technology’s blue LED-based water purification system used current levels very near the limit of those rated for the blue light-emitting diodes, they would still last years compared to UV generating mercury-vapor lamps. If the concept goes on line, it will probably be the water purification method with the lowest carbon footprint given the energy efficiency of light-emitting diodes.