Underwater discharge and cell destruction by shockwave

Summary form only given. An arc discharge in water can produce shockwave, ultraviolet radiation and radical species. In this paper, we have investigated discharge characteristics. Microbe cells in sludge are destroyed by shockwaves generated from electrical discharge. An arc discharge was generated by applying a pulsed voltage of V=20/spl sim/30 kV to the tip or coaxial electrodes. Capacitance of C=30 nF was used. A tungsten tip and coaxial stainless steel was used as electrodes. We also used oscilloscope to investigate discharge characteristics and the Closed Reflux Titrimetric Method (K/sub 2/Cr/sub 2/O/sub 7/ Oxidation method) to measure COD (Chemical Oxygen Demand) increase by cell destruction. The arc discharge occurs after a certain delay time. Shockwave is produced only for the arc discharge. Shockwave intensity is mostly related to the discharge energy, and is the most effective parameter of sludge cell destruction. It is also a function of discharge circuit, pulse duration, water conductivity, electrode size, gap distance and reactor configuration. We introduce discharge model. The /spl omega/-P graph obtained from the experiments is described in terms of electrode length in coaxial reactor. Sludge treatment data by underwater arc discharge is also presented.