Methods and apparatus for treating waste are provided. Waste is converted in an arc plasma-joule heated melter system utilizing one or more arc plasma electrodes and a plurality of joule heating electrodes. The arc plasma electrode(s) can be configured for operation utilizing AC or DC power, or for switching between AC and DC power. The arc plasma electrodes can also be configured for independent arc voltage and arc current control. The joule heating circuits are configured for simultaneous operation with the arcing electrodes, but without detrimental interaction with the arcing electrodes. The systems provide stable, non-leachable products and a gaseous fuel. The gaseous fuel can be utilized in a combustion or non-combustion process to generate electricity.