Pulsed Arc Electrohydraulic Discharge characteristics and plasma parameters of sludge-water

Storm water detention/ retention ponds are designed to settle and trap sediments carried by storm water runoff. However, as the service time of the facilities increases, the accumulation of pollutants in sediment also increases hence the contaminants of a liquid fraction in storm-water sediment (sludge-water) should be treated before discharge to the river. The Pulsed Arc Electrohydraulic Discharge (PAED) is identified as one such treatment techniques. The generation of radicals and electrons, emission of UV-A and pressure impulses are essential for decontamination process in storm-water sludge. In this work, an experiment investigation of a Pulsed Arc Electrohydraulic Discharge characteristics and plasma parameter were conducted. The system consisted of a spark-gap-type power supply (0.5kJ) and a 3L stainless steel reactor with eccentrically configured rod-to-rod electrodes, the water gap distance was fixed at 0.5mm. Optical emission spectrum, UV-A and UV-B emissions were observed during the discharge period. Based on optical emission spectra, a significant amount of hydrogen was generated. Oxygen and hydroxyl radicals were also detected from the optical emission. UV-A was observed during the discharge period while UV-B was not observed due to attenuation by the presence of sludge. Discharge channel volume averaged plasma parameters such as plasma density, electron temperature, pressure wave intensity and total heating energy were determined from the fundamental discharge characteristics. The maximum plasma density, electron temperature and pressure wave intensity reached the order of 10²² ions/ cm³, 1 eV and 10¹² Pa/sec respectively. The maximum pressure impulses at the bottom and side of the reactor wall were 0.7 and 1.7 Pa.sec respectively. The total heating was 0.34 J within a full discharge period. The effect of sludge fraction will be discussed in detail.