Biobased, biodegradable and compostable plastics: chemical nature, biodegradation pathways and environmental strategy

Increasing pollution of plastic waste is one of the major global environmental threats, deteriorating our land, water and air. The shift towards biobased, biodegradable and compostable plastics is considered a green alternative to petroleum-based plastic due to its renewable source or biodegradability. However, there is a misconception about biodegradable plastics and their degradability and behaviour after service life. Biobased, biodegradable and compostable plastics offer various benefits such as less carbon footprint, energy efficiency, independence and eco-safety. On the other hand, there are some disadvantages such as higher cost, limited recycling, misuse of terms and lack of legislation. Also, there is an urgent need for comparable international standard methods to define these materials as biodegradable material, or biocompostable material. There are some standards currently available, however, an in-depth detail and explanation of these standards is still missing. This review outlines the basic definition and chemical structure of biobased, biodegradable and compostable plastics; describes the degradation pathways of biodegradable and compostable plastics; and summarises current key applications of these materials together with possible future applications in different industries. Finally, strategies are developed for minimising the environmental impacts and the need for future research is proposed.

Microbial degradation of four biodegradable polymers in soil and compost demonstrating polycaprolactone as an ideal compostable plastic

Plastics are an indispensable material but also a major environmental pollutant. In contrast, biodegradable polymers have the potential to be compostable. The biodegradation of four polymers as discs, polycaprolactone (PCL), polyhydroxybutyrate (PHB), polylactic acid (PLA) and poly(1,4 butylene) succinate (PBS) was compared in soil and compost over a period of more than 10 months at 25 °C, 37 °C and 50 °C. Degradation rates varied between the polymers and incubation temperatures but PCL showed the fastest degradation rate under all conditions and was completely degraded when buried in compost and incubated at 50 °C after 91 days. Furthermore, PCL strips showed a significant reduction in tensile strength in just 2 weeks when incubated in compost >45 °C. Various fungal strains growing on the polymer surfaces were identified by sequence analysis. Aspergillus fumigatus was most commonly found at 25 °C and 37 °C, while Thermomyces lanuginosus, which was abundant at 50 °C, was associated with PCL degradation.

Role of compostable tableware in food service and waste management. A life cycle assessment study

It is estimated that in Europe 88-100 million tonnes of food waste are generated every year, with a Global Warming Potential (GWP) of around 227 MT of CO₂ equivalents generated for their collection and disposal. A 12% of this waste is estimated to arise from food service within the hospitality sector, which includes quick service restaurants, casual and fine dining, contract catering (canteens, prisons, hospitals, schools etc.) as well as indoor and outdoor events and exhibitions. Given this considerable amount and that the mixed unsorted collection is often the only practicable way to handle such waste flows, the choice of tableware and cutlery can make a big difference in facilitating waste collection as well as in reducing the overall environmental impact of food waste management. This study compares the environmental performance of using biodegradable & compostable single use tableware with organic recycling of food waste through composting against a traditional scenario using fossil-based plastic tableware and disposal of the waste flows through incineration and landfill. The study has taken into account the main requirements of the recently published Product Environmental Footprint (PEF) methodology of the European Commission. The results confirm that the use of biodegradable and compostable tableware combined with organic recycling is the preferred option for catering in quick service restaurants, contract catering and events, since it reduces significantly the carbon, water and resource footprint and is fully in line with the principles of a circular economy.