An incinerator for the disposal of biohazardous waste has a sealed enclosure defining a combustion chamber with upper, first level intermediate, second level intermediate and lower portions. The upper chamber portion is an inclined chute with a door into which a plurality of cylindrical metal containers of waste are loaded. The bottom run of the chute has a stepped, centrally expanding dimension so different sized containers will be self-centered. A pair of laterally-spaced drums is disposed in the first level intermediate portion, at a constriction which stops further descent down the chute of the leading container. Banks of first level TIG torches are arranged to arc to the drums, providing heat for "cooking" waste in the unopened containers in the upper portion with rising gases and for opening the leading container and incandescently acting on solid materials spilled therefrom. A large ribbed drum, laterally-spaced from another drum, in the second level intermediate portion provides a second more secure constriction to limit the size of particles passed to a solid residue collection hopper in the lower portion. Second level TIG torches are to the second level drums to further act on the waste. Heated gases are collected at the top of the chute and recirculated to the second level intermediate portion. Heavier gases are passed to scrubbers, and the hopper is emptied to a residue discharge bin in the lower chamber portion. The torches are cyclically fired by high voltage delivered sequentially from coils by distributors, and sustained by direct connections through diode arrays to common power sources. The cyclic firing provides mechanical agitation to the waste during processing, and common electrode arrangements redirect power to clear shorts.