A plasma reactor to convert waste material by thermal plasma into one or more desired end products, comprising - a reaction volume delimited by walling, a gas outlet port and a melt treatment unit, wherein said gas outlet port delimits the reaction volume from the top and said melt treatment unit delimits the reaction volume from the bottom, and wherein - when the plasma reactor is in operation - the reaction volume is connected to both the gas outlet port and the melt treatment unit to maintain a free flow of material there through, and wherein the reaction volume includes a gaseous material treatment region, a gasification region and a melt treatment region, the gaseous material treatment region opens directly to the gas outlet port, the melt treatment region at least partially forms part of the melt treatment unit and the gasification region is located between the gaseous material treatment region and the melt treatment region; - a waste material supply mechanism passing through the walling and opening into the gasification region of the reaction volume; - plasma torches arranged to generate thermal plasma in each of said regions (5A, 5B, 5C) of the reaction volume separately, wherein at least one plasma torch is provided for generating the thermal plasma in each region (5A, 5B, 5C); - sensors (11, 11') arranged in said regions (5A, 5B, 5C) of the reaction volume, the sensors (11, 11') are configured to monitor physical and/or chemical conditions prevailing within said regions (5A, 5B, 5C) and to measure physical/chemical parameters representative of said conditions at given instances when the plasma reactor is in operation; - a data collecting and control unit, wherein said sensors (11, 11') are in data communication connection with the data collecting and control unit for transferring measurement data obtained by measurements performed by the sensors, the measurement date being representative of the instantaneous physical and/or chemical conditions prevailing within said regions (5A, 5B, 5C) when the plasma reactor is in operation; wherein each plasma torch comprises an arc forming material supply inlet for introducing arc forming material into the reaction volume and an additive supply inlet for introducing additive into the reaction volume, wherein the additive is provided by a substance that is necessary for the conversion of the waste material into the one or more desired end products, and wherein at least some of said additive supply inlets is configured to allow real-time control of feeding of said substance into the thermal plasma in the reaction volume by the respective plasma torch upon a control signal produced and outputted by the data collecting and control unit based on the measurement data of said sensors (11, 11') and preset operational parameters for the operation of the plasma reactor. - a reaction volume delimited by walling, a gas outlet port and a melt treatment unit, wherein said gas outlet port delimits the reaction volume from the top and said melt treatment unit delimits the reaction volume from the bottom, and wherein - when the plasma reactor is in operation - the reaction volume is connected to both the gas outlet port and the melt treatment unit to maintain a free flow of material there through, and wherein the reaction volume includes a gaseous material treatment region, a gasification region and a melt treatment region, the gaseous material treatment region opens directly to the gas outlet port, the melt treatment region at least partially forms part of the melt treatment unit and the gasification region is located between the gaseous material treatment region and the melt treatment region; - a waste material supply mechanism passing through the walling and opening into the gasification region of the reaction volume; - plasma torches arranged to generate thermal plasma in each of said regions (5A, 5B, 5C) of the reaction volume separately, wherein at least one plasma torch is provided for generating the thermal plasma in each region (5A, 5B, 5C); - sensors (11, 11') arranged in said regions (5A, 5B, 5C) of the reaction volume, the sensors (11, 11') are configured to monitor physical and/or chemical conditions prevailing within said regions (5A, 5B, 5C) and to measure physical/chemical parameters representative of said conditions at given instances when the plasma reactor is in operation; - a data collecting and control unit, wherein said sensors (11, 11') are in data communication connection with the data collecting and control unit for transferring measurement data obtained by measurements performed by the sensors, the measurement date being representative of the instantaneous physical and/or chemical conditions prevailing within said regions (5A, 5B, 5C) when the plasma reactor is in operation;