Second US team tests AlGaN LED water treatment
Ohio-based start-up company Oh Technology (OHT) claims to have reduced bacteria levels in flowing raw sewage by 60% using ultraviolet LEDs manufactured by Sensor Electronic Technology (SET).
OHT's first battery of tests, which began in February this year, looked at the effect of a prototype module containing 16 AlGaN LEDs emitting at around 270 nm on raw fecal sewage at a local wastewater treatment facility.
According to the team, which included third-party testers at Tri State Laboratory, the influent samples that contained fecal coliform bacteria showed a 60% reduction in bacteria concentration after a one-second flow-through. These bacteria are found in the digestive tract, and include classes such as enterobacter, citrobacter and E coli.
Concentrations of these bacteria are commonly used as an indicator of sewage contamination in water supplies.
"The test results have provided proof of the basic viability and instant kill efficiency of the LEDs," said OHT.
Company CEO Damien Lieggi added: "We wanted to start with the worst possible water conditions we could find. We feel we achieved tremendous results at this level."
Another company targeting LED-based water treatment, Hydro Photon of Blue Hill, Maine, is also using devices made by SET to treat these types of bacteria (see related story), and recently showed that it could reduce E coli concentration by up to 99% in contaminated flowing water.
The development of portable LED-based water sterilization units should reduce the size of current systems that use conventional mercury vapour lamps, while it could also reduce the requirement for chlorine-based chemical sterilization in the long term.
