An evaluation of quantification methods for plastics

The objective was to investigate and compare methods for quantifying the concentrations of different plastics in stock samples. Five types of plastics were added to clean, bleached, hardwood pulp stock. The plastics concentrations in the stock samples were 0.10%, 0.50%, 1.0%, and 2.0%, based on the oven-dried weight of the pulp. Samples were processed and analyzed by four quantification methods : image analysis, screening, passage through a hydrocyclone, and vacuum flotation. Screening was the most efficient and reliable method for quantifying plastics. Application : as recyclers delve deeper into the waste stream to recover fiber, they will need efficient methods for quantifying the amounts of plastic contaminants in the recycled wastes.