Recycling Process for Shipboard Generated PWP Waste

Since January 1989, U.S. Navy ships have been retaining most of thei r plastic waste for disposal ashore in accordance with new Navy policy. The desired goal of recycling this densified waste in the form of commingled plastic blocks presents unique processing problems that are not encountered when processing/recycling municipal and commercial plastic waste. PWP waste is in a shredded, partially fused, and non-sortable form along with food and other non-plastic contaminants. The processing system proposed by Foster-Miller to separate and recover the Navy's PWP waste utilizes a variety of commercially available as well as innovative equipment. All of the proposed separation equipment will be used in one of two completely independent processing techniques to recover different plastics. These autonomous separation methodologies are based on particle density and melt temperature differentials. System 1 will encompass a more traditional size reduction, cleaning, and separation of the less dense plastics that comprise as much as 85% of the waste. This fraction will subsequently be recovered using a melt filtration/compounding process. In system 2, the steps of cleaning and separation will be eliminated in a simpler process that enables the recovery of lower melting plastics from the PWP waste stream. This system will utilize a novel melt separation technique whose feasibility will be demonstrated in Phase I. Molded sheet obtained from each system will be compared for a variety of mechanical properties. At the end of Phase I one of these two systems will be chosen for Phase II scale-up based on a cost/benefit analysis.