TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Method: A electrothermal treatment zone for waste material treatment is prepared involving at the first stage the plasmotrons operating on steam heat carrier or at the second stage a molten pool of metal or oxides in frequency melter of direct induction heating. The molten pool is saturated with oxygen injected through the bottom oxygen lance(s). For electrothermal treatment, preparation of the waste materials includes densification, briquetting and transportation of the waste material into the electrothermal treatment zone without preliminary heating. The waste material briquette is retained in the molten pool by weight force of the briquettes mass loaded from above onto the molten pool and simultaneously processed by descending streams of steam plasma and ascending oxygen jet introduced through bottom oxygen lance(s) at a ratio of waste material and plasma to be close to stoichiometric one prior to full disintegration of the briquette said, mixing waste material with molten metal and electrothermal treatment of the waste material prior to formation of low-ash condensed residues and combustible gases (syngas). The excess of oxygen-containing plasma to waste material composition loaded into the electrothermal treatment zone does not exceed 2% of stoichiometric ratio. The treatment temperature of waste material in the plasma treatment zone is 2000 - 2500degreesC and in the molten pool zone is 1700 - 2500degreesC. The organic ingredients of waste material are converted in the electrothermal treatment zone to thermodynamically stable gas consisting predominantly of hydrogen and carbon monoxide. Both the molten pool and inorganic ingredients of the waste material entering inside the pool are subjected continuously to direct induction heating from a frequency power source independent of arc plasmotrons power supply. The step (j) is carried out by electromagnetic forces prior to formation of homogeneous melt of low ash inorganic residue or by ascending oxygen jet introduced through bottom oxygen lance(s) prior to formation of homogeneous melt of low ash inorganic residue. The initial electrical conductivity of the molten metal pool is re-established after mixing with the waste material and sustained in the range of 1 - 100 Siem/m by plasma heating from above and by transportation of waste material inorganic ingredient melt from the plasma reactor. The inorganic ingredient melt is overflowed continuously from the frequency melter at pouring above the coil of the frequency power source. The outflow of syngas is cooled and quenched with a rate not lower 108 C/s to temperature of 70 - 90degreesC. The vapors of the low-melting metal toxic ingredient (preferably mercury, zinc, lead, cadmium), containing in the syngas flow, are condensed at the stage of cooling the syngas. The outflow of syngas is cleaned of technological dust in two-stage system of dust catching. The bulk of technological dust is removed from the syngas by electrofiltration. The syngas flow is cleaned of fine technological dust with the use of filtration of the flow through cermet filters made of anisotropic ceramics supplied with blow-back regeneration of filtering surface. The blow - back of filtering surface is carried out by already cleaned syngas. The aerosols of the low-melting metal toxic ingredient are caught and isolated at the stage of filtration through the cermet filter. The toxic mixtures (preferably hydrogen fluoride, hydrogen chloride, sulfur and nitrogen oxides) are separated of the bulky flow of the syngas are isolated one after another in the form suitable for utilization. The syngas flow with the mixtures is passed through the sorption column filled with pelletized sodium fluoride at temperature approximately 150degreesC and purified of hydrogen fluoride completely by sorption on sodium fluoride in the form of acid sodium fluoride, followed by heating sodium fluoride with sorbed hydrogen fluoride to 35degreesC such that anhydrous hydrogen fluoride desorbs and is collected in the form of product having commercial value. The hydrogen fluoride desorbed is collected into a condenser at a lower melting temperature of -87.2degreesC. The syngas flow purified of hydrogen fluoride, containing the residual toxic gas mixtures is passed through suspension of calcium oxide in water and purified to hydrogen chloride, nitrogen oxides, sulfur oxides while chlorine is caught in the form of calcium chloride, sulfur oxides are caught in the form of calcium sulfate and calcium sulfite and higher nitrogen oxide are caught in the form of calcium nitrate. The calcium sulfate and calcium sulfite are precipitated in the suspension and removed periodically from the suspension after pouring off the solution saturated on calcium chloride. The calcium nitrate is removed from absorption column together with calcium chloride or from the suspension in the form of solution together with calcium chloride. Preferred Apparatus: The upper part of the electrothermal treatment zone is performed in a vertically arranged cylindrical plasma reactor and lower part is performed as conical widening and then as conical narrowing in the form of truncated cones. The plasma reactor is made of stainless steel and is supplied with double cooling jacket along overall its length including both cylindrical zone and zones of widening and narrowing. The inner cooling jacket and the outer jacket is cooled by air-flow and water flow respectively. The plasma reactor is supplied with several plasmotrons for generating steam plasmas introduced inside the reactor through surface of conical widening. The number of the plasmotrons is not less three. The arc plasmotrons are supplied with generators of overheated steam. The steam generator is supplied with damper. The arc plasmotrons are introduced inside the plasma reactor downwards at an angle within 30 - 45degrees to the plasma reactor axis. The angle between the plasma reactor axis and conical widening generatrix is of 45degrees. The angle between the generatrixes of surfaces of the conical widening and conical narrowing is of 90degrees. The preparation and transportation devices of waste material are performed as horizontally arranged conduit attached to the cylindrical portion of the plasma reactor above the conical widening. The conduit for preparation and transportation of waste material are supplied with vertically situated loading hopper and a receptacle with a cover for dosing a waste material briquette. The conduit for preparation and transportation of waste material are supplied with the horizontally situated hydraulic pressure operating in reciprocating operating mode. The frequency melter of direct induction heating is performed as a set of vertically installed water-cooled elongated sections made of non-magnetic metal hermetically installed between the upper and lower collectors of cooling water combined with fastening flanges and separated with vertical clearances for free penetration of electromagnetic energy from the coil. The width of the clearances between the vertical elongated sections of the frequency melter is within 1 - 2 mm. The clearances between the sections of the frequency melter are filled in with inserts made of high temperature dielectric material. The vertical elongated sections of the frequency melter are supplied with insulating coatings made of alumina. The elongated elements are supplied with inlet and outlet collectors of cooling water. The upper fastening flange of the frequency melter is air tight attached to lower fastening flange of the plasma reactor. The frequency melter is supplied with water-cooled bottom hermetically attached to the lower flange. The induction melter is installed coaxially in the coil of the frequency power source in such a way that a distance between the top end of the clearance and the upper turn of the coil is equal to a distance between a lower end of the clearance and the lower turn of the Coil and both distances are equal to a coil height. The frequency melter diameter is equal to a diameter of lower portion of the plasma reactor. The oxygen lance(s) for oxygen injection are introduced vertically into the bottom of the frequency melter. A frequency of the frequency power source is 2 - 350 kHz or 0.440 - 5.25 MHz for melting inorganic ingredients of waste material such that a share of metallic fraction is 20 - 100%. The frequency melter is positioned inside the air tight protective sheath made of non-magnetic metals, installed between the top and the bottom flanges of the frequency melter. The coil branches are air tight lead out towards the frequency power source through the high voltage insulating inserts in the wall of the protective sheath. The unloading device for pouring off the melt of metallic, ceramic and salt ingredients of the waste material is performed in the form of conduit positioned just above the upper turn of the coil. The overflow conduit is lined with graphite or silicon carbide. The unloading device includes the tubular collector supplied with a heat valve in the bottom zone of the collector for pouring off the melt products. The overflow conduit is air tight lead out through a wall of the protective sheath. The conduit for outflow of the syngas is disposed in the upper portion of the plasma reactor. The cooling device provides cooling rate of the syngas from temperature 1700 - 2000degreesC to 70 - 90degreesC with a rate not lower 106 C/s. The cooling device of the high temperature outflow of syngas is in the form of a recuperative heat exchanger, of which the lower part is connected with the top of the plasma reactor by the conduit and the outflow of the syngas cooled is located at the upper portion of the heat exchanger. The cleaning device of the syngas of technological dust is performed to be two-stage for separate catching the bulk of the technological dust and for separate catching if fine disperses dust and aerosols. The first stage of the cleaning device for catching the bulk of technological dust is performed as electrofilter installed just after the recuperative heat exchanger in such a way that the upper portion of the heat exchanger is connected with the lower portion of the electrofilter by a conduit. The second stage of the cleaning device for catching fine technological dust and aerosols is performed as cermets filter installed just after the electrofilter in the hopper in such a way that the upper portion of the electrofilter is connected with the lower portion of the hopper said by a conduit. The hopper is supplied with an air tight cover and an inner air tight barrier dividing the hopper to two chambers. The tubular cermets filter elements installed vertically inside the hopper in such a way that they pierce air tight the barrier. The lower end of each cermets filter elements is welded and the upper end is open. The hopper is supplied with conical exit in the lower portion, with a conduit lower the barrier for introducing of the dusty syngas, with a conduit higher the barrier for outflow of cleaned gas and with a cover with nozzles vertically piercing the cover. Each nozzle vertically piercing the hopper cover is aligned along the center line of each cermet filter element. Each cermet filter tube is supplied with a blow-back impulse ejection regeneration system. The system of blow-back impulse ejection regeneration includes a receiver with compressed syngas, electromagnetic valves, nozzles and timer for automatic impulse time control. The fine purification device of the syngas of hydrogen fluoride mixture comprises two sorption column installed in parallel filled with palletized sodium fluoride for chemical sorption of hydrogen fluoride mixture from the syngas. One column operates in the operating mode of sorption and another for desorption. The sorption column operating in desorption regime is connected to a condenser for catching of hydrogen fluoride. The fine purification device of the syngas of mixtures of hydrogen chloride, sulfur and nitrogen oxides comprises two absorption column installed in parallel filled with calcium oxide suspension; one column operates in the operating mode of absorption and another for separation of calcium chloride, calcium nitrate, calcium sulfate and sulfite. The apparatus further includes a computer communicating with waste preparation, briquetting and transportation device, with electrothermal treatment device, with a device for unloading condensed products and for cooling, cleaning and fine purification of the syngas and with a device for monitoring and controlling the performance to provide apparatus start-up, operation and shut-down. EXAMPLE - No relevant example given.