The sorting method contains a fuzzy system that classifies waste into three classes: dangerous (toxic, flammable, harmful to the environment), recyclable and undetermined. To increase the decision weight since some waste is perilous (eg. batteries, spray bottle under pressure, oil drums, etc.), we implement a shapesignature identification algorithm.The extraction of objects contour in order to obtain the signature is done with contour tracking algorithm. The appropriate determination of contour also enables efficient calculation of shape and size features used in fuzzy system. The elaborated system aims to detect dangerous wastes that arrive among the recyclable waste because of people ignorance.