The Role of Compostable Plastics in Nutrient Recycling: Environmental Impact of Biobased Teabags in a Circular Economy

Abstract Following the EU’s Packaging and Packaging Waste Regulation, packaging inseparable from food waste, such as teabags, must be industrially compostable, facilitating joint composting and supporting circular economy goals by enabling nutrient recycling. Utilizing home-compostable materials, however, could have additional advantages by mitigating collecting and waste management activities. The biobased and home-compostable polymer polybutylene succinate (PBS) is a potential candidate for these applications, e.g., in teabags. Through an inductive case study approach, this cradle-to-grave Life Cycle Assessment (LCA) evaluates environmental benefits and trade-offs of employing PBS in teabags compared to industrially compostable polylactic acid (PLA) and non-compostable polypropylene (PP). The assessment incorporates a detailed emission inventory of microplastics, a rising environmental concern linked to conventional plastics. Results highlight that the primary environmental impacts of PBS teabags arise during the use phase, followed by the production phase, whereas home composting exhibits minimal environmental impact (approximately − 0.1%). Scenario analyses illustrate that outcomes significantly depend on end-of-life management practices, notably the substitution of chemical fertilizers through compost utilization. Differences in the fertilizer utilization rate can lead to a variation of up to 20.61% in environmental impacts. The substitution benefit is attributed to tea leaf waste rather than the PBS material itself. The findings also show that PBS teabags are environmentally beneficial compared to PP only if home-composted rather than incinerated. Furthermore, adopting PBS mitigates microplastic pollution, which was investigated through microplastic leakage estimations, and advances circular economy objectives by enabling resource regeneration and transforming food waste into valuable compost. This study underscores PBS as a sustainable material option, contributing directly to the circular economy by reducing waste incineration, enhancing resource recovery, and minimizing plastic pollution.