Abstract: The processing of combustible, partially combustible and non-combustible liquid waste at preferably high temperatures. The vertical combustion chamber is preferably round with liquids introduced from the top by spray nozzle or similar means and being treated as the liquid falls. Heat for preheating or processing comes from a number of flat flame radiation type burners addressing the falling liquid mostly by radiation heat. The number and arrangement of the auxiliary burners depends on the liquid to be processed and the furnace capacity. The auxiliary burner type and arrangement prevents flame impingement by the falling liquid. During the processing of certain liquids, the falling liquid will be totally surrounded by flames, from the top of the combustion chamber to a point at which no more processing is required. The discharge gases exit at the lower end of the combustion chamber and are beneficially utilized. For maximum efficiency, the liquid is air preferably air atomized.