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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

Biodegradable Plastics - Developments and Environmental Impacts

Nolan-ITU Pty Ltd
Prepared in association with ExcelPlas Australia
October, 2002

Conclusions

The conclusions to the national review of biodegradable plastics are presented below against the Terms of Reference.

Identify the various types and composition of biodegradable plastics available, and likely to be available in Australia

Over the last few years there has been a significant expansion in the range of biodegradable plastics which are commercially available or are under commercial development. This trend is expected to continue. The range of biodegradable plastics available include:

There is an extensive range of potential applications. Some of these include:

Whilst some biodegradable plastics are used for some of these applications in Europe, the current market penetration into Australia is low. This is generally limited to some films including landfill cover, food service cups, cutlery and trays, and loose fill foam. There have also been trials of other applications such as shopping bags, mulch film, EVOH bottles and bait bags.

Identify standards and test methods for biodegradable plastics in Australia

There are currently no Australian standards and test methods for biodegradable plastics. There is a need to establish Australian Standards that match the potential application areas and disposal environments in Australia.

Internationally, there are several standards that could be applied, or adapted, to meet the requirements of the Australian market place. The most comprehensive appears to be the various ASTM standards and test methods. These address the various degradation methods and a range of disposal environments.

There are also several standards for compost derived products including the Australian Standard AS 4454-1999 Compost Soil Conditioners and Mulches, as well as standard testing procedures for plant and animal toxicity.

Examine the range of disposal methods and identify the most frequent disposal option for each biodegradable plastic application at end of life

The major disposal environments for biodegradable plastics are:

To a large extent, the nature of the biodegradable plastic application should dictate the disposal environment. Further LCA studies are required to determine appropriate disposal routes for different polymers and products.

The most common, and perhaps desirable, method of disposal is composting as this results in the production of a useful end product. Landfill disposal, particularly for garbage bags is also a significant disposal route. Wastewater treatments plants are only suitable for flushable products that have an extremely rapid degradation rate. There has been some development work with bait bags and fishing lines although the results are not conclusive. As with flushable products a rapid degradation rate is required.

Despite community education programmes and enforcement, litter will continue to be a disposal route for biodegradable as well as degradable plastics.

Identify current technologies to avoid contamination and sort biodegradable plastics in Australia and overseas

The risk of contamination by biodegradable plastics of conventional plastics which are currently recycled and reprocessed, from both kerbside and industrial recycling systems, is a significant one. This could result in changing the characteristics of the material and may lead to a failure of products as degradation occurs. Even a minor increase in failure would be significant in many applications. The growing confidence in recycled plastics could be eroded if technical integrity is comprised.

There are a range of measures to sort different polymers. Initially this is a manual exercise relying on sorting staff being able to recognise and differentiate items based on knowledge of material use in different product categories. This is then backed up at some plastics reprocessors with sorting technologies based on specific gravity or optical sorting equipment. This is difficult when biodegradable plastics have similar physical properties to recyclable plastics.

The best technology to sort biodegradable plastics from non-biodegradable plastics may be near infra-red (NIR) detection which can be used in a positive sort system. The NIR system can be tuned for example to positively sort starch-based polymers and in this way a pure biodegradable stream could be segregated for composting. The viability of NIR detection systems at a commercial scale is beyond the scope of this review.

Describe and assess the environmental impacts arising from the foreseeable increase in use of biodegradable plastics in various applications

There are several identifiable environmental benefits that may potentially be derived from the use of biodegradable plastics compared to conventional petroleum-based plastics. These are:

Biodegradable plastics also pose some adverse environmental risks. These include:

Identify possible and excisting solutions to identified impacts and limitations

For the successful introduction of degradable plastics into Australia it is essential that for any new application that the following are clearly identified:

For this to be achieved it will be necessary to establish a national framework for standards and testing. This can be based upon appropriate international standards. It is recommended that the Federal Government, through Environment Australia and in consultation with the plastics industry, take an initiating role in undertaking further research and developing these standards.

Further research focus areas include: