Electric discharge treatment of water containing organic substances

摘要

High standards of drinking water quality and growing man-caused pollution of the environment require new technologies of water treatment that would allow to increase the efficiency of water purification and not to contribute any impurities by adding chemical reagents during treatment. Highly efficient are the technologies of simultaneous action of several factors, such as ultraviolet radiation and "environment-friendly" oxidizers: ozone, hydrogen peroxide etc., also being of particular interest due to synergetic effect. This multifactor treatment can be effectively realized using cold plasma of electrical discharges in water-air medium. The discharge is able to produce not only ozone and atomic oxygen, but also a number of particles, typical for water medium (OH, H/sub 2/O/sub 2/, HO/sub 2/ etc.). These particles with very high chemical activity can oxidize a wide range of impurities in water, from metals to complex organic compounds. In our work we describe a system of water treatment using pulsed dielectric barrier discharge in water-air system. Dielectric barrier, placed between the electrodes, provides better distribution of discharge over the whole interelectrode gap, and prevents shorting the gap with water droplets. Power is supplied to the system from nanosecond pulse generator, the amplitude of voltage is 25 kV, pulse repetition rate is up to 1 kHz. Quasi-volume discharge, formed in the interelectrode gap, covers water droplets, and this helps to obtain better purification results, even for water contaminated with complex organic substances. In the present work we report the results of treatment of water containing phenol and thichloroethylene. Energy consumption has been measured and efficiency comparison of our system with other electric discharge treatment and ozonation systems has been made. High energy efficiency of our process compared to other technologies (about 13-14.6 g of phenol per kW-h) has been shown.