Abstract

INVESTIGATION OF UNDERWATER STREAMER DISCHARGES FOR WATER DISINFECTION

S. B. GUPTA, H. BLUHM

Forschungszentrum Karlsruhe

Institute of Pulsed Power and Microwave Technology

PO Box: 3640 Karlsruhe 76021 (Germany)

e-mail: suryakant.gupta@ihm.fzk.de

In this paper we would like to discuss about a new physical disinfection method based on pulsed underwater corona streamer discharges. Corona streamer discharges are nonthermal discharges with a low degree of ionisation and electron densities. Due to short pulse duration and strong electric fields (up to few MV/cm) at the streamer head, it produces electrons having sufficient energies to dissociate and ionise water and oxygen molecules. Due to these processes a large number of strong oxidants (OH-radicals, H₂O₂, Ozone, and others) and UV-radiation are created. In addition to the above effects pressure waves of few hundred MPa are created at the head of the streamer discharge. It is supposed that the combination of all effects leads to a very efficient killing of microorganisms.

At Forschungszentrum Karlsruhe, Germany we have designed a special cylindrical configuration reactor with a special ceramic-coated electrode mounted at the centre. This helps to get uniformly distributed streamers in the treatment reactor. We have optimised and characterised the physical and electrical parameters for corona discharges. Special diagnostic methods are under development to measure the yield of oxidants quantitatively. It is expected that the production of oxidants occur with high energetic efficiency. This may help to reduce the cost of water treatment. Finally concepts for the scaling to large throughputs shall be developed and the corresponding plant and operating costs shall be estimated.