Challenges in bioplastic waste management and impact of biodegradable plastics on municipal waste streams : a review

Abstract

Bioplastics are proposed as a solution to mitigate the environmental impact of staggering plastic production. They include plastics derived from biomass or capable of biodegrading into environmentally benign materials. The non-biodegradable portion, primarily drop-in bioplastics, are chemically identical to conventional plastics but use biomass instead of petrochemicals. As a result, they are compatible with existing infrastructure. However, integrating biodegradable plastics remains challenging due to their distinct formulations. Currently, their market share is too small to justify separate sorting streams, leading to minimal recycling. They degrade slowly in the environment and are not widely accepted in composting or anaerobic digestion facilities, often resulting in landfill disposal or incineration. The EU has actively supported bio-based plastics to reduce fossil dependency and promote a circular economy while regulating biodegradable plastics for applications where degradation provides clear benefits, such as agricultural mulch films and fishing gear. Among biodegradable plastics, polylactic acid (PLA) and polyhydroxyalkanoates (PHAs) are experiencing the fastest global market growth, projected to increase from 780 kt in 2023 to over 4.2 Mt by 2028. While the EU discourages replacing conventional recyclable plastics with biodegradable alternatives, more than half of the biodegradable plastics are used in packaging, making separate sorting streams inevitable. Other biodegradable plastics, including cellulose- and starch-based materials, are expected to maintain a stable market, with closed-loop collection systems being the most viable approach. The new Packaging and Packaging Waste Regulation (PPWR) expands recycling definition to include compost of biodegradable plastics as recycled material. This highlights the importance of reducing conventional plastics in the biowaste stream, particularly in Finland where the reject rate can be as high as 10% due to contamination. Starch-based bags for waste should be expanded and replace non-biodegradable bags in biowaste stream, which needs public awareness, technological advancement and regulatory support. Reverse vending machines can also be adapted with new materials like PLA bottles, which could improve recycling rates, encourage reuse, facilitate temporary campaigns, and prevent bioplastics from contaminating other recycling streams.