A waste treatment system is provided, including a waste melter system and an air pollution control system. Hazardous and/or radioactive waste in drums is conducted through a waste feed system into a plasma chamber where the waste is exposed to heat from a plasma torch. A part of the waste volatilizes and leaves the plasma chamber for a secondary reaction chamber, in which the waste is combusted to form a waste gas stream. The air pollution control system treats the waste gas stream through quenching, filtering and scrubbing, to produce a clean gas stream suitable for release to the atmosphere. Offgas may be recirculated through the waste treatment system as desired. The waste remaining inside the plasma chamber melts and drops onto sloped processing surfaces inside a hearth located below the plasma torch. The hearth includes ground electrodes configured for electrical contact with waste held in the hearth so that the melted waste in the hearth may be further heated by the plasma torch. As the melted waste is heated inside the hearth, the hearth is static, enabling the melted waste to separate into a first metal fraction having a high specific gravity and a second slag fraction having a relatively lower specific gravity. When the melted waste is processed sufficiently, the hearth is first lowered from the plasma chamber and then tilted in a first direction to pour the slag fraction and then tilted in another to pour the metal fraction from under an underflow weir configured in the hearth. The hearth includes a second ground electrode strategically situated near the underflow weir to ensure that the waste remains melted as it flows through a flow path under the underflow weir.