'Degrading Plastic Bags' Daniel Burd, 2008 "Best of Fair" Winner
In 2008, then 16-year-old Daniel Burd, discovered a way to decompose plastic bags in as little as three months, winning the top prize at the Canada-Wide Science Fair.
The decomposition of some plastic bags is estimated to take as long as 1000 years. With this in mind, Daniel set out to identify microorganisms that can break down plastic.
During his research Daniel isolated two microbial strains that appeared to most successfully degrade polyethylene (the most common plastic). Taking optimal concentrations of these two strains, Burd added sodium acetate to promote bacterial growth, and placed the mixture among several strips of common grocery bags. 43% degradation of the plastic was achieved within six weeks.
Burd is confident that this method can be applied on a larger scale, stating “Industrial application should be easy. All you need is a fermenter. . . your growth medium, your microbes and your plastic bags.”
Similar to the law in South Australia, the Northern Territory and the ACT, it appears that the Tasmanian state government will also follow suit in implementing restrictions on certain kinds of plastic bags. The date in which the legislation comes into force is not yet confirmed, but appears to be around late 2013. Despite contradictory evidence as to their effectiveness, plastic bag bans are a popular legislative option for a government to "appear green."
More details can be found here:
Just a quick 2 minute, very basic explanation of the difference between a compostable bag and a degradable bag. There is some more info on our blog about this topic, as it is a commonly asked question. Just search for "compostable" in the search tool.
Most people in Australia will be aware of the Plastic Bag Ban which is in various states of effectiveness in South Australia, Northern Territory and the ACT. The Plastic Bag Ban makes exceptions for Compostable Bags which are compliant with Australian Standard AS4736 - 2006. This standard is for "Biodegradable plastics suitable for composting". This means that Compostable Bags are allowed, where Degradable Bags are not. The question that many people ask is WHY ??? Well, for the answer to this - we need to look at the AS4736 - 2006 standard, to see how they define compostability. In order for a something to be "compostable", the following 4 criteria must be met:
Now the only difference between Compostable Bags and Degradable Bags is with criteria number 2. A Degradable Bag will biodegrade slower than a Compostable Bag in a commercial composting environment. But is the rapid degradation speed in the standard fair? Biodegradation in 180 days is pretty fast. Even some natural items such as leaves can take as long as 1 -2 years to break down! Even a leaf isn't considered "compostable" by the standard - how appropriate can the standard really be? If the objective of the plastic bag ban is to reduce plastic bag litter, then the exemption of AS4736 - 2006 Compostable bags - at the exclusion of degradable bags is actually counter intuitive and wrong.
With some states legislating for a "plastic bag ban" - several national retailers have sought alternatives to the humble plastic singlet bag. Most alternatives revolve around bags manufactured from other materials. The below list gives an idea of the approximate costs associated with alternate materials in comparison to plastic singlet bags.
Maxpak can supply all of the alternatives mentioned above.
A problematic effect of the Plastic Bag Ban in various states of Australia, are reports that Compostable Bags (AS4736 Compliant) have had problems acutally degrading in compostable environments - As reported by the City of Monash in Victoria: Although the bags will break down into organic material eventually, they do not break down quickly enough for the green waste processing equipment to handle. And also, a report from the City of Maroondah in Victoria: Maroondah Council has asked residents not to put so-called compostable bags in garden waste bins. Mayor Peter Gurr said the bags "often failed to breakdown as promised" and posed a risk of contamination and increased processing costs. Acting chief executive officer Vern Steele said the cornstarch-based bags were "just not compatible" with available composting systems. Also compounding the problem are instances of companies engaging in misleading, deceptive and fraudulent conduct: From at least May 2009 it was claimed that 'Goody' branded plastic bags were biodegradable and compostable in accordance with the Australian Standard* and that they could be legally supplied in South Australia, when this was not the case as the bags:
These examples of rorts and non performance, really call into question the wisdom of Government's legislating for an "environmental winner."
How will the carbon tax affect the supply of plastic bags and plastic packaging? Interestingly enough, there is a school of thought that poses the question of whether such products would be eligible for tax credits under a "Carbon Tax" or "Emissions Trading Scheme."
The recently announced Carbon Tax is designed to reduce carbon emissions into the atmosphere by pricing the emissions at $23.00 per tonne.
Plastic bags are made as a byproduct of the process of refining oil. Ethane and Propane, along with hundred of other petrochemical products are all refined from crude oil. Every environmentalist around the world is trying to get people to stop emitting carbon into the air, and a plastic bag is essentially carbon - captured in the form of a product which will not be emitted into the atmosphere.
There are millions of barrels of oil per year that are forever locked up in a simple plastic bag. Carbon that is permanently sequestered as a plastic bag that will never be emitted is much better than the greenhouse gases which are unleashed when producing paper bags (which actually increase carbon in the atmosphere by removing trees from the environment) and also than "compostable bags" which emit another greenhouse gas - methane, into the atmosphere during degradation.
So,that being said - what is the likely result of the Carbon Tax on these products? Perhaps manufacturers could be accredited to sell carbon credits or get a rebate from the government?
Wishful thinking probably...
With legislation regarding compostable bags appearing in South Australia, Northern Territory and the ACT, it has become important to understand the meaning of the different terms which exist for the various materials available. The terms "biodegradable bags", "degradable bags"and "compostable bags" are often misused. To add to the confusion, other terms such as hydro-degradable and oxo-degradable have also been introduced to the vernacular. No wonder people are left bewildered! It feels like we all need to get a polymer science degree just to understand the terms, and this leads to a great deal of confusion in the market place.
What does it all mean?
ASTM D883-99 defines "Degradable Plastic" as "a plastic designed to undergo a significant change in its chemical structure under certain conditions resulting in a loss of some properties that may vary as measured by standard test methods appropriate to the plastic and the application in a period of time that determines its classification."
Degradable plastics, also known as "oxo-degradable" plastics describe when traditional polyethylene is treated with pro - degradent additives at the point of extrusion. This allows the finished product to undergo a two stage process after being triggered by sufficient exposure to a combination of UV light, heat and mechanical stress. The process firstly causes chemical reactions within the film to become extremely brittle - losing substantial tensile strength, elasticity and molecular weight. The plastic film ends up resembling minute "dust" particles. Secondly, these smaller molecules are ingested by micro organisms - causing the film to be biodegraded into carbon dioxide, water and bio mass.
Compostable plastics, also known as "hydro - degradable" plastics are developed from a different raw material - typically a fusion of traditional polymers and starch based components. The "hydro - degradation" process is quite similar to the "oxo - degradation" process. Both undergo initial chemical reactions which cause deterioration in the molecular weight of the film, followed by biodegradation by micro organisms. However the trigger for the process for Compostable plastics is being in the presence of high bacterial / microbial environment. The end result is identical: carbon dioxide, water and biomass.
With the processes sounding similar, and the end results being the same - are there any other differences? Well, yes ...
"Biodegradable Plastics" - what are they? According to ASTM D883-99 a "Biodegradable Plastic" is "a degradable plastic in which the degradation results from the action of naturally-occurring micro-organisms such as bacteria, fungi, and algae." With such a definition, it can be inferred that both "Degradable" and "Compostable" plastic bags are ultimately "Biodegradable" at their end point.
At this time, in South Australia and the Northern Territory a plastic bag ban is in effect. The ACT will soon follow in November 2011. Plastic bags which are prohibited must meet the following 3 criteria: Which bags will be banned? The ban will prohibit retailers from selling or giving away
What about bags with '100% degradable' printed on them? Only compostable bags that comply with Australian Standard AS4736-2006 will be permitted. They are not made from polyethylene, but usually a starch compound - and are usually quite expensive (approximately 7 times the price.) Be careful about suppliers misrepresenting products as AS 4736 compliant. The ACCC has already taken action against companies engaging in misleading conduct regarding the representation of compostable bags. (eg: The Federal Court in Adelaide has declared that Goody Environment Pty Ltd engaged in misleading and deceptive conduct and made false representations about 'Goody' branded plastic bags.)
What are the penalties?
If a supplier provides a retailer with bags they know are banned, they will be guilty of an offence from 4 May 2009. Maximum penalty: $20,000 Retailers will face on-the-spot fines of $315 or a maximum fine of $5000 for breaching the ban. Transitional arrangements. During transitional periods into the full ban, retailers are usually permitted to continue using normal plastic bags - on the condition that they also offer an alternative in the store. The alternative may be offered to their customers at a price or for free - it is up to the retailer. Check your local authorities to be certain. Maxpak has a range of solutions for companies who face restrictions due to the Plastic Bag Ban. Please contact us, and we can consult with you to find the best solution for you.
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