Silent discharge water treatment: Mass transfer and reaction rates

Mass transfer and rate of de-colourization of a dye, methylene blue, were studied using both conventional ozonation and dielectric barrier discharge through oxygen in the same reactor. Experiments were done in the same apparatus to allow comparison of rates under the two modes of operation in order to determine the impact of discharge based mechanisms. Argon was also used in the discharge reactor to eliminate contributions to de-colourization from ozone formed in situ.; The dielectric barrier discharge system showed enhancements to ozone mass transfer and de-colourization rates when compared with conventional ozonation of 2 to 5 times. The rate of de-colourization was enhanced in excess of the rate of mass transfer, indicating that additional mechanisms are operative in the discharge system. The discharge based mechanisms were found to have a constant effect on de-colourization that can be added to the ozone contribution to achieve the overall rate of de-colourization. The best overall degradation rate was achieved in a single experiment with argon under vacuum, yielding nearly an order of magnitude improvement over conventional ozonation.; This technique shows great promise as a water treatment method, with a shorter required residence time and increased efficiency in transfer and use of ozone as compared with conventional ozonation systems.