Sensor Fusion for Contaminant Detection and Removal from Plastic Recycle Streams

Post-consumer plastics have become a tremendous burden upon our waste disposal system. Although plastics constitute only about 9 percent by weight of municipal solid waste, they occupy approximately one-fourth the volume of the waste stream. The U.S. EPA recommends recycling of plastics as the best solution to the problem. However, contamination of plastics within the recycle stream by foreign materials is a major impediment to widespread plastics recycling. Post-consumer recyclables are of inherently low value in the marketplace and have to compete with low-cost mass- produced virgin materials. Consequently, for recycling of plastics to be economically viable, it is necessary that processing systems for recycled plastics be highly efficient and low cost. Efficient, high-speed sorting technology has been developed recently by National Recovery Technologies (NRT) to remove troublesome contaminant polymers from plastics during processing for recycling. A remaining significant problem is the presence of small metallic contaminants in the plastics stream, which cause considerable problems to the processor during the extrusion of recycled plastics in making new products. Removal of these metallic contaminants using existing technology has proven to be difficult and expensive. The Phase II research is directed toward development of an efficient, cost-effective technology for small metals detection and removal from the recycled plastics stream and for integrating this technology into a shared resources environment with NRT's FlakeSort - high speed polymer sorting technology based on the information obtained during Phase I.