TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The hydroxy radical generating unit is used for injecting hydroxy radical to a hydroxy radical generator nozzle installed with a permanent magnet, which is a mixture of null valence iron, water and compressed air mixed with a mixer. The lower part of the drying reactor is installed with a discharge screw (54) to discharge dry solids. The generated hydroxy radicals move through a hydroxy radical distributor (30) provided with hole on both sides of the space, and are separated by the space between the permanent magnet, which is installed on north and south poles and arranged by repulsive force with laminated surface. The hydroxy radical generating unit comprises a compressed air feeder, a water feeder, a null valence iron feeder for supplying null valence iron, a hydroxy radical generator provided with multiple rod permanent magnets. The mixture of null valence iron, water and compressed air is supplied to a hydroxy radical reactor for generation of hydroxy radical using the permanent magnet. The hydroxy radical generating unit supplies the null valence iron and water through an intermittent solenoid valve in a metering pump, where the intermittently supplied null valence iron and water are mixed with the compressed air, delivered to a pipe by penetrating through the center portion of the hydroxy radical generator, and injected to the inner bottom of the hydroxy radical generator through an injection nozzle of the pipe. The hydroxy radical generating unit is connected to the hydroxy radical distributor. The hydroxy radical generated from the hydroxy radical generating unit is supplied to the quantitative input unit through the hydroxy radical distributor. The hydroxy radical distributor distributes the permanent magnet. The mixing unit mixes the thermal medium containing activated sludge and waste oil, where the mixture is heated at 100-150 degrees C by the radical reaction in the quantitative input unit. The drying reactor evaporates water added to the mixture in the mixing unit, utilizes water escaping from the sludge instead of waste oil, and discharges the dried solids from the lower part. The device further comprises a gas purification unit for purifying volatile organic compounds generated from the drying reactor and the quantitative input unit. The gas purification unit purifies organic volatile gases, which are supplied through the permanent magnet by the radical reaction. Preferred Method: The step (c) comprises injecting sludge activated by hydroxy radical reaction in a sludge mixer, then injecting the sludge mixed with thermal medium containing waste oil in a drying reactor and heating at 100-150 degrees C and evaporating moisture, and utilizing water coming out from the sludge instead of waste oil. The volatile organic compounds generated in first and second step are removed by radical reaction, where the radical reaction is performed within the gas purification unit separated by the space between the permanent magnet.