In a method and to an arrangement for treating a light fraction produced during the treatment of plastic-rich waste that is low in metal, at least the following steps are carried out consecutively: the light fraction is stressed by percussion and/or bashing, the light fraction is classified into at least two light fraction classes, at least one light fraction class is separated into at least one dust fraction and at least one other fraction, the separation of the dust fraction taking place over a substantially controlled residence time of the light fraction class in at least one device involved in the separation. Due to the separation of at least one light fraction class into at least one dust fraction and at least one other fraction, the separation of the dust fraction takes place over a substantially controlled residence time of the light fraction class in at least one device involved in the separation, a very pure intermediate product (intermediate fraction) is produced, providing the processability of the intermediate product to be improved in subsequent method steps. Overall, clearly improved material recycling and also energy recovery is obtained.