NOVELTY - Composite device comprises (i) a first portion comprising a sludge tank (1), a methane tank (2), and anti-explosion device (3), a biogas pipeline (4), a auger pump (5) fixed to a feeding tube; (ii) a second portion comprising a filter layer-based pressure filtration tank, a filter groove fixed to an underground pipeline; (iii) a third portion comprising a high temperature carbonization furnace, a feeding port, a secondary smoke combustion equipment, a combustion switch and a combustion pipe and a discharge port; and (iv) a fourth portion comprising e.g. smoke dust purification device.    USE - The composite device is useful for producing synthetic fuels from sewage sludge (claimed).    ADVANTAGE - The composite device does not produce toxic- and harmful- smoke by carrying out secondary combustion heating using smoke dust air device, where smoke is subjected to purification treatment, and is discharged based on standards; converts waste into useful materials, and thus it produces renewable resources through circulation process.    DETAILED DESCRIPTION - Composite device comprises (i) a first portion comprising a sludge tank (1) which is connected to a methane tank (2), and anti-explosion device (3), a biogas pipeline (4), a auger pump (5) which is connected to a feeding tube; (ii) a second portion comprising a filter layer-based pressure filtration tank, a filter groove which is connected to an underground pipeline; (iii) a third portion comprising a high temperature carbonization furnace, a feeding port, a secondary smoke combustion equipment, a combustion switch and a combustion pipe and a discharge port; and (iv) a fourth portion comprising a smoke dust purification device, a draught fan and smoke dust pipeline, a circulation pump, a multi-layered spraying device, a water washing spray tower, a fog layer spraying unit, a spraying head located on upper water pipeline, and an air outlet.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the composite device.    Sludge tank (1)    Methane tank (2)    Anti-explosion device (3)    Biogas pipeline (4)    Auger pump (5)