Plasma treatment units consist of several sub-systems besides
the thermal plasma source. These components are: a waste feed
system, a processing chamber, a solid residue removal and handling system, a gas management system, operational controls and
data acquisition and monitoring. A modern plasma system to treat
waste incinerator ash is described elsewhere [19]. Briefly, it consists
of a DC hollow graphite cathode installed though the roof of a furnace and supported by a vertical manipulator column. Nitrogen is
injected down the centre of the cathode to produce a stable plasma
arc that is transferred to the furnace melt; the anode consists of
conductive elements built into the furnace hearth and the process
is capable of handling a wide range of ashes of varying particle size
and composition.