A non-transferred plasma torch with a tungsten cathode and
copper anode was used in Korea to evaluate the reduction in volume and removal of hazardous elements in fly ash and sludge from
wastewater treatment on a laboratory scale [38]. The leaching test
on the vitrified slag showed that metals, such as copper, zinc and
lead and other heavy metals leached below the regulatory limits.
Plasma treated mixes of fly ash and sludge also had leachabilities
below the regulatory limit.