Study: Pre-sorting plastic waste at home leads to higher quality

China News Service, Beijing, June 4 (Reporter Sun Zifa) A recent environmental science paper published in the international academic journal "Nature" stated that a study concluded that plastics recovered from household pre-sorted plastic waste are of higher quality than plastics recovered from mixed waste at recycling facilities in the Netherlands.

The researchers believe that while mixed waste without pre-sorting may increase overall recycling volumes, it comes at the cost of lowering the quality of the recycled product. This finding highlights the need for improved recycling collection and sorting systems.

Schematic diagram related to this research (picture from the paper). Photo courtesy Springer Nature

According to the paper, global plastic production continues to grow and will exceed 413.8 million tons in 2024, but the recycling rate is only 9%. Sorting plastics is critical to properly recycling products, but public cooperation can be a bottleneck, and material recovery facilities are limited in their ability to sort different plastic types.

In this study, to determine whether mixed recycling collection can increase waste recycling rates without reducing quality, corresponding author Steven De Meester of Ghent University in Belgium, together with colleagues and collaborators, evaluated plastic bales for recycling at a waste treatment plant in the Netherlands. They compared waste collected separately from consumers to mixed recycling, both of which go through material recovery processes in factories.

The authors analyzed the plastic bales for their composition, contaminants, moisture content, odor, and the presence of metals and other unwanted substances. The plastic composition is similar between bales, but mixed plastic bales contain more contaminants, including banned metals such as cadmium and lead, which can pose health risks to humans if not removed before recycling. Mixed recycling also increases moisture and dirt content, requiring additional cleaning procedures.

The authors of the paper then further ran a material flow model to evaluate how much more recycled raw materials could be added if recycling facilities in Europe and the United States were able to sort more mixed waste. Although the study showed an increase in recycling volume, there is an economic cost - to increase the volume of mixed waste recycling by 75%, Europe would need to invest approximately 18 billion euros and the United States would need to invest approximately $50 billion to build post-sorting infrastructure.

The authors conclude that their findings suggest that sorting at the consumer level is the best way to ensure the quality of recycled products, but that collecting mixed recyclate and sorting it at recycling facilities could be a complementary strategy. For follow-up research, more work needs to be done to reduce contaminants and improve material collection. (over)