Many different materials are used for container and packaging, including metals, glass, wood, paper or pulp, plastics, and combinations of more than one material as composites. Most of these enter municipal waste streams at the end of their service life.
In recent years, the recycling of packaging materials has increased but the recycling rates for most plastic packaging remain low. A large number of different types of polymers, each of which may contain different processing additives such as fillers, colourants and plasticizers, are used for packaging applications. These composition complexities together with contamination during use often render recycling uneconomic compared with disposal in landfill.
Biodegradable plastics with functionalities and processabilities comparable to traditional petrochemical-based plastic have been developed for food containers and packaging applications. Typically, these are made from renewable raw materials such as starch or cellulose. Interest in biodegradable plastic food container and packaging arises primarily from their use of renewable raw materials (crops instead of crude oil) and end-of-life waste management by composting or anaerobic digestion to reduce landfilling. The disposal of packaging materials is particularly significant in view of the recent focus on waste generation and management.
In addition to performance and price, biodegradable plastics must offer advantages for waste management systems in order to realize an overall benefit. This article discusses the potential impact of biodegradable plastics, with particular reference to food container and packaging. It provides an overview of the key life cycle issues that inform judgements of the benefits that such materials have relative to conventional, petrochemical-based counterparts.
Biodegradable polymers (BDPs) or biodegradable plastics refer to polymeric materials that are ‘capable of undergoing decomposition into carbon dioxide, methane, water, inorganic compounds, or biomass in which the predominant mechanism is the enzymatic action of microorganisms, that can be measured by standardized tests, in a specified period of time, reflecting available disposal condition’.
There are many technologies available for the treatment of conventional plastic food container and packaging waste from household waste, including integrated collection and incineration with energy recovery, selective combustion of plastics with high calorific value and use as a reducing agent in blast furnaces or as feedstock for recycling.
As biodegradable polymers enable a potential option for waste treatment through composting as a way to recover the materials and to produce a useful product as compost, particular attention will be given to composting biopolymers.