Large area pulsed corona discharge in water for disinfection and pollution control

To investigate the efficiency of submerged pulse corona (SPC) discharges in water we built a laboratory scale, parallel-plate reactor that is part of a closed loop water circulation system. A pulsed voltage is applied across the electrodes. One of the electrodes is coated with a porous ceramic layer to create local field enhancements to initiate corona discharges. For energization of the SPC reactor a pulse generator was developed which is based on a capacitor discharge initiated by a semiconductor switch. A pulse transformer, followed by two magnetic pulse compression stages, produces voltage pulses with amplitudes of up to 30 kV at a pulse width of 0.3 ¿s. Simulation of the circuit behavior leads to good agreement with voltage and current measurements. Details of the pulse generator and first experimental results concerning the efficiency of radical production are presented. Depending on the conductivity of the water to be treated, pulse currents of > 600 A at a voltage of 20 kV to > 30 kV are obtained for electrode sizes of around 50 cm2. The efficiency of the radical production is measured in terms of the hydrogen peroxide (H2O2) concentration, which is formed by recombination of hydroxyl radicals (OH.) at sufficiently high concentrations downstream of the plasma reactor. At pulse repetition rates of 20 to 100 Hz, H2O2 concentrations of several mg/l are produced, at efficiencies in the range of up to ¿1 g/kWh.

[1]  W. Hartmann,et al.  All-Solid-State Power Modulator for Pulsed Corona Plasma Reactors , 2007, IEEE Transactions on Dielectrics and Electrical Insulation.

[2]  P. Lukeš,et al.  Generation of ozone by pulsed corona discharge over water surface in hybrid gas–liquid electrical discharge reactor , 2005 .

[3]  P. Lukeš,et al.  Hydrogen peroxide and ozone formation in hybrid gas-liquid electrical discharge Reactors , 2004, IEEE Transactions on Industry Applications.

[4]  K. Schoenbach,et al.  Bacterial decontamination of water by means of pulsed corona discharges , 2001, PPPS-2001 Pulsed Power Plasma Science 2001. 28th IEEE International Conference on Plasma Science and 13th IEEE International Pulsed Power Conference. Digest of Papers (Cat. No.01CH37251).

[5]  Abdul Ghaffar,et al.  Water purification by electrical discharges , 2001 .

[6]  H. Akiyama.  Streamer discharges in liquids and their applications , 2000 .

[7]  E. Sakai,et al.  Ozone Generation by a Discharge in Bubbled Water , 1999, Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358).

[8]  J. Sid Clements,et al.  Formation of chemical species and their effects on microorganisms using a pulsed high voltage discharge in water , 1994, Proceedings of 1994 IEEE Industry Applications Society Annual Meeting.