Degradable plastics and their potential for affecting solid waste systems

摘要

Plastic waste forms a substantial part of municipal solid waste and has caused environmental concerns, particularly due to the chemical contamination of the environment and effects from persistent litter. Plastics also complicate waste management processes, such as by having poor recovery rates through recycling and causing contamination in composting operations. One potential means of addressing some of these challenges is through degradable plastics, which unlike conventional plastics, are designed to decompose at an accelerated rate in specific environments. Degradable plastics aim to address the end-of-life of plastic products and are intended to reduce the environmental impacts associated with their use and management. The first generation of degradable plastics did not meet marketing claims; some of the more recent formulations, partly as a consequence of third party certifications, are more compliant. However, many plastics that are labelled as degradable do not decompose very readily, and it is not clear that litter will be diminished to any great degree through their use. In addition, user confusion regarding degradable definitions is common. Multiple formulations mean that not all degradable plastics address compost contamination and most degradable plastics do not address other problems associated with plastics waste management. Therefore it is not clear that degradable plastics constitute a major technological advance. In fact, they may be more harmful than helpful to waste management systems at this time. Here we discuss how these materials perform in different aspects of solid waste programs: recycling, composting, WTE incineration and landfills, as well as the potential for these plastics to reduce litter problems, both on land and at sea.