A system is disclosed for incinerating fluid (liquid and/or gas) and solid waste including a first, second, and third combustion zones of successively larger interior volumes. Liquid wastes are introduced into the first combustion zone and solid wastes are introduced into the third combustion zone, whereby solid wastes are heated from conduction and/or convection by the first and/or the second combustion zone prior to the solid wastes being introduced into the third combustion zone.