Method for operation of a system for thermal preparation of reclaimed road material containing PAHs, or of oil sludges, which comprises following system components: a) a loading station (10; 110) for pre-comminuted reclaimed road material or oil sludges (11; 111); b) a rotary tube kiln (13; 113) in which the reclaimed road material (11; 111) or the oil sludges are burned, while oxidation air is fed in; c) a dust separator (16; 116) to which the flue gases produced in the rotary tube kiln (13; 113) are fed; d) an after-burning device (20; 120) to which the flue gases leaving the dust separator (16; 116) are fed; e) a filtering device (24; 124) to which the flue gases arising in the after-burning device (20; 120) are fed, characterized in that f) the system components (10, 13, 16, 20, 24; 110, 113, 116, 120, 124) according to the features a) to e) are divided into a plurality of modules (2, 3, 4; 102, 103, 104) each of which have a weight and dimensions, such that they may individually be transported using low loaders or trucks; g) the modules (2, 3, 4; 102, 103, 104) are positioned in spatial proximity to the point of origin of the reclaimed road material containing PAHs or of the oil sludges; h) the modules (2, 3, 4; 102, 103, 104) at least in part are connected to one another by pipes or hoses (17, 22; 117, 122) that are of a variable shape; i) after task completion at a first point of origin the modules (2, 3, 4; 102, 103, 104) are disconnected from each other and are transported to a next point of origin; wherein k) an additional module (5; 105) is used in which the components required to supply the other modules (2, 3, 4; 102, 103, 104), in particular a power unit (27; 127), tanks (28, 29, 30, 31; 128, 129, 130, 131) for operating media such as water, gas, compressed air, fuel, are grouped together. a) a loading station (10; 110) for pre-comminuted reclaimed road material or oil sludges (11; 111); b) a rotary tube kiln (13; 113) in which the reclaimed road material (11; 111) or the oil sludges are burned, while oxidation air is fed in; c) a dust separator (16; 116) to which the flue gases produced in the rotary tube kiln (13; 113) are fed; d) an after-burning device (20; 120) to which the flue gases leaving the dust separator (16; 116) are fed; e) a filtering device (24; 124) to which the flue gases arising in the after-burning device (20; 120) are fed, characterized in that f) the system components (10, 13, 16, 20, 24; 110, 113, 116, 120, 124) according to the features a) to e) are divided into a plurality of modules (2, 3, 4; 102, 103, 104) each of which have a weight and dimensions, such that they may individually be transported using low loaders or trucks; g) the modules (2, 3, 4; 102, 103, 104) are positioned in spatial proximity to the point of origin of the reclaimed road material containing PAHs or of the oil sludges; h) the modules (2, 3, 4; 102, 103, 104) at least in part are connected to one another by pipes or hoses (17, 22; 117, 122) that are of a variable shape; i) after task completion at a first point of origin the modules (2, 3, 4; 102, 103, 104) are disconnected from each other and are transported to a next point of origin; wherein k) an additional module (5; 105) is used in which the components required to supply the other modules (2, 3, 4; 102, 103, 104), in particular a power unit (27; 127), tanks (28, 29, 30, 31; 128, 129, 130, 131) for operating media such as water, gas, compressed air, fuel, are grouped together.