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Bags not! Finding the solution for Australia’s plastic bags

Plastic BagsThe recent Ministerial Roundtable on plastics could not agree whether to ban, price or leave Single Use Plastic Bags (SUPBs) for another day. We use approximately 6 billion SUPBs each year, of which 2 percent are recycled[i].

SUPBs are being, or have been, banned in South Australia, Tasmania, the ACT, the Northern Territory and in some localised townships.

The choice of ban vs. price (say a 10 cent levy) is one of economic efficiency. Bans are black or white, while pricing leaves room for progressive behaviour change and infrastructure development, while potentially raising money for worthy causes.

But it is pretty clear that there is finally a national appetite to address SUPBs. Whether agreed or not, it is important that we get the transition right. Let’s be very careful that we do not replace 6 billion SUPBs with something that doesn’t work. We still need to go shopping.

Also many councils are now offering householders Food Organics and Garden Organics (FOGO) collection bins to recover the 60% of organics an average household generates. These 3 bin services usually involve a small kitchen tidy and the supply of bio-bags. The FOGO that is collected is usually taken to a large composting facility. SUPBs are a big problem in composting facilities, but so are many of their so-called alternatives.

So if we do away with SUPBs, what do we replace them with, especially for our shopping and FOGO services?

The alternatives

The short answer is we need to replace them with compostable bags. What does that mean?

In the Australian marketplace we talk of ‘degradable’, ‘biodegradable’ and ‘compostable’ bags. There are also ‘oxo-degradable’, ‘solar-degradable’, ‘recycled’, ‘recyclable’ and ‘reusable’. Not much help.

They are not equal. They are not the same and most of these gum up composting facilities.

A ‘degradable’ bag is usually made from plastic, such as polyethylene, with a polymer added to ensure breakdown over time (after exposure to light, oxygen and heat) into small fragments. They break down to create lots of small bits of plastic (micro-plastic) which are as bad, if not worse than SUPBs.

They are also a complete pain in composting facilities. Since it breaks down into micro-plastic it contaminates the finished compost product.

Bottom line – ‘degradable’ bags are not a good solution.

Some plastics manufacturers include additives to accelerate degradation and label these bags as ‘biodegradable’. However, the term ‘biodegradable’ is very loosely used.

The School of Packaging at Michigan State University summed it up well: “The ultimate goal of biodegradation is to totally break down the molecular structure of the polymer, returning the carbon in the plastic to the normal geological carbon cycle. In many cases, biodegradable bags do not achieve this state and leave behind physical residue in the form of micro-plastic (typically any piece of plastic less than 5mm long and sometimes not visible to the naked eye), including microbeads[ii].”

Bottom line – ‘biodegradable’ is not a reliable definition for something that will compost and not pollute.

‘Compostable’ bags on the other hand, are made from plant material such as starch[iii]. They break down completely into ‘humus’, carbon dioxide, heat and water.[iv] (they also fully decompose in composting facilities).

The Australian Organics Recycling Association (AORA) supports a ban on all SUPBs. Similarly, it seeks confirmation that all replacement products are ‘compostable’ and meet the requirements of Australian Standards 4736 and AS5810 for composting.

Bottom line – ‘compostable’ replacements offer a viable alternative.


We have got to get this transition right.

Organic waste represents over 50 percent of all waste we landfill, or 10 million tonnes. It is 60% of what an average household generates.

Organic waste in landfill breaks down anaerobically, to generate methane, which if not captured, leaches into the atmosphere. Methane is a potent greenhouse gas (25 times the global warming potential of carbon dioxide) and accounts for 11 million tonnes of Australian greenhouse gas emissions per annum.

There are transition issues we need to consider. It is true that until we get national FOGO bin servicing, that many compostable bags will end up in landfill and contribute a tiny amount to methane generation. But they are such a small percentage of landfill tonnages (0.1%), that their contribution during the roll out of FOGO nationally will be negligible.

Councils and food retailers with food or organics collection services, need to ensure their tenders specify ‘compostable’ bags that meet AS4736.

So here is the takeaway message. A compostable bag is biodegradable. But a biodegradable bag is not necessarily compostable. So if it is not certified ‘compostable’ – don’t use it.

As always, I welcome your feedback on this, or any other topic on ‘The Tipping Point’.

[i] Banning plastic bags – the tip of the iceberg –

[ii] ‘Biodegradable’ plastics don’t live up to manufacturers’ claims –

[iii] Compostable vs degradable. Whats in a name? –

[iv] The difference between biodegradable and compostable packaging materials –


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