High-Power Pulsed Corona for Treatment of Pollutants in Heterogeneous Media

A technical overview of a European project on pulsed corona (PC) treatment of polluted streams is presented. Versatile high-power systems that are capable of cleaning both aqueous and gaseous streams in heterogeneous media, in either a corona above water reactor or an aerosol reactor, have been developed. Both reactors are capable of high-phenol removal yields from aqueous streams and increase the biochemical oxygen demand/chemical oxygen demand ratio for several nonbiodegradable wastewaters to such degree that further biodegradation becomes possible. The PC combined with a catalyst is capable of cleaning gaseous streams that are polluted by toluene, styrene, and malodorous constituents. Reduction rates of toluene that are higher than 99% have been achieved, and very high odor-removal efficiency has been demonstrated. The reliable operation of high-power all-solid-state compact nanosecond pulsers has also been demonstrated. For the second phase of the project, a high-power pulser was designed. One compression stage suffices for the formation of 60-kV 3-J pulses across a reactor that has a discharge impedance of approximately 100 Omega at a pulse repetition frequency of up to 500 Hz; the rise time is 15 ns, and the duration is 100 ns. The system scale-up is also analyzed. The estimated price of water treatment in systems that were scaled up to 50 m³ /h is 2 euro/m³. Incineration of aqueous organic waste streams can cost 500 euro/m³ or more, depending on the nature of the contamination, so the PC water-treatment technology may become highly competitive. It is planned in the future to investigate the cleaning efficiency of the developed processes with different industrial wastes, both at laboratory conditions and in the field