"Oxo-biodegradable plastic" question
Baglady of Kingston upon Thames
plastic when I noticed that the bag says it's made from "oxo-
biodegradable plastic". Googling found that this is plastic with
additives that cause it to degrade faster and more easily than other
plastics, aparently to almost nothing ("water, carbon dioxide and
biomass" according to http://en.wikipedia.org/wiki/Oxo_Biodegradable),
but also that it can be recycled with other plastics. There are lots
of claims out there that it is truly green, mainly I suspect from
manufacturers - and I'm now wondering whether this is really a miracle
product (both plastic and biodegradable - and plastic was once
minerals and maybe can return to this state) - or whether this is just
greenwash and yet another way that plastic could get into the food
chain.
Does anyone out there know?
Marilyn, Greener Kingston.
Chris Cant
What you are describing sounds like what I would call "degradable"
plastic, so is different to what is normally called "bio-degradable".
This is from a degradable bag additive maker:
http://www.degradable.net/how/in_detail.shtml
The alternative view is provided by the biodegradable industry association:
http://www.european-bioplastics.org/media/files/docs/en-pub/European_Bioplastics_OxoPositionPaper.pdf
I am not utterly certain what oxo-degradable plastic breaks down
into. I also suspect that in practice they take a reasonable length
of time to degrade, so will be polluting for that time. And it is
still made from plastic.
On the other hand, if you can put such plastic in the ordinary
plastic bag recycling then that is good. I have also been told of
degradable plastic bags made from recycled plastic. It's good to
have a use for recycled plastic. I've been told that recycled
plastic can never be used for food-contact bags, which seems slightly
surprising as it must be melted at high temperature.
--
On biodegradable bags, eg cornstarch:
You shouldn't put biodegradable plastic into the plastics
recycling. However I suspect that this happens a lot. One
biodegradable bag I've seen only says what it is in very small
writing and doesn't say not to recycle it.
I put a mater-bi cornstarch bag in a plastic marge carton full of
earth in May 2009. When I looked recently it had gone brittle but
definitely had not disappeared, as you might have
suspected. Obviously this is not a perfect composting medium, but
none-the-less realistic.
I'm still pretty wary about putting all the home-compostable bags
into our slow/cold compost heap. Does anyone else have any experience of this?
How good/bad is it if biodegradable bags go to landfill? Does it
depend on whether the landfill collects any methane produced?
--
I've written up some of this here:
http://chriscantrant.blogspot.com/2010/01/alternatives-to-plastic-bags.html
--
Obviously, as you know, it's best not to have plastic at all, though
I'm sure there's a case in this instance if you include
transport/production (energy) costs, eg for a lightweight postal
wrapper vs paper.
Chris, Penrith
CarryAbag
Yes, I've been conducting a bit of research with cornstarch compostable
bags. A friend has house rabbits so I offered the composting facilities. The
cornstarch bags are filled with the bunny poo, bedding and newspaper.
To start with we just piled them up and it was noticeable that the bags on
the outside stayed intact. The bags at the bottom of the pile in a dark
moist environment broke down and attracted worms after about six months.
So I then transferred them to the main compost heap along with veg and
garden waste. I have found it best to split them open so that rain gets in
and keeps them wet, this seems to help them breakdown.
The bags that have been in the heap for about a year can now been seen as
shreads through the compost. So they are breaking down but it takes time.
I'm now experimenting with composting them in one of those black plastic
(did I say that word) compost bins to see if this wetter environment makes
them break down more quickly.
Cheers
Donna
Lets Make Chesham Plastic Bag Free!
www.PlasticBagFreeChesham.co.uk
Marilyn
Chris, Penrith
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TonyB
The argument over whether a degradable bag is biodegradable /
compostable has been answered by Defra and Loughborough University
with the publication of a large study. The whole study can be found
http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None&Completed=0&ProjectID=16263#Description
and the associated press release here http://www.defra.gov.uk/news/2010/100311c.htm.
You will see from the press release that the Co-op have stated they
are moving away from this technology, and have in fact launched a
certified home compostable carrier bag in some stores (see below).
Tesco have not made any statement about their carrier bags yet.
When it comes to whether something that claims to be biodegradable is
industrially compostable or home compostable there are important
things to know (it is a complicated situation):
Biodegradable - on it's own means nothing and if you see a product
which just claims to be biodegradable then avoid it.
Compostable - this means it should comply with the European Standard
EN13432, this claim should be backed up by independent certification
and carry an associated logo - the seedling logo or OK Compost.
However, in this context, compostable means industrially compostable,
i.e. will compost safely and quickly in a plant operating at high
temperatures. The seedling logo or OK Compost logo does NOT mean it is
suitable for home composting. Due to the fact the biopolymers industry
moves faster than government, there are a large number of products on
the market which claim to be suitable for home composting, show the
seedling logo and get away with it but that's about to change....
Home Compostable - very shortly (in the next weeks I think) the
Association for Organics Recycling will launch a new scheme to certify
products which are suitable for home composting. This is the scheme
that the Co-op uses for its new bags. Home composting operates at
lower temperatures and longer time scales than industrial composting,
so a product which is certified as home compostable (and carries the
new logo) will compost in a reasonably well run home composter in 12
months.
I will update when this new scheme is launched but when it is, any
product claiming to be home compostable will have to be certified by
the Association for Organics Recycling or face a charge of false
claims.
Chris - I don't know which grade of Mater-Bi you buried in the soil,
but the chances are it was a home compostable grade and in this case
the raw material is likely to be certified as OK Biodegradable Soil by
Vincotte in Belgium. This is a further level of certification which
operates at lower temperatures and for longer, in this case the test
takes 24 months so your bag should be gone by next spring.
Donna / Chris - for a home compost heap to be composting, not just
slowly biodegrading, it needs a combination of nitrogen and carbon
rich materials (e.g. grass and straw / twigs), oxygen and moisture are
also important, the composting mass should be as wet as a freshly
wrung out sponge. These conditions along with warmth (either sunlight
or from microbial energy) will provide the best conditions for the
bugs to do their magic. There's lots of info on www.recyclenow.com/home_composting
The key to whole thing is not to believe a word people say unless you
have seen their certification
Best wishes
Tony
On 11 Feb, 16:16, "CarryAbag" <carrya...@plasticbagfreechesham.co.uk>
wrote:
> The alternative view is provided by the biodegradable industry association:http://www.european-bioplastics.org/media/files/docs/en-pub/European_...
> I've written up some of this here:http://chriscantrant.blogspot.com/2010/01/alternatives-to-plastic-bag...
>
> --
> Obviously, as you know, it's best not to have plastic at all, though I'm
> sure there's a case in this instance if you include transport/production
> (energy) costs, eg for a lightweight postal wrapper vs paper.
>
> Chris, Penrith
>
> At 16:09 10/02/2010, you wrote:
> >I was idly wondering why the RSPB still sends me stuff wrapped in
> >plastic when I noticed that the bag says it's made from "oxo-
> >biodegradable plastic". Googling found that this is plastic with
> >additives that cause it to degrade faster and more easily than other
> >plastics, aparently to almost nothing ("water, carbon dioxide and
> >biomass" according tohttp://en.wikipedia.org/wiki/Oxo_Biodegradable),
Baglady of Kingston upon Thames
scepticism confirmed!
Marilyn
On Mar 16, 6:29 pm, TonyB <tonybre...@gmail.com> wrote:
> Hi
>
> The argument over whether a degradable bag is biodegradable /
> compostable has been answered by Defra and Loughborough University
> with the publication of a large study. The whole study can be foundhttp://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location...
> and the associated press release herehttp://www.defra.gov.uk/news/2010/100311c.htm.
> > For more options, visit this group athttp://groups.google.com/group/plasticbagfree?hl=en.- Hide quoted text -
>
> - Show quoted text -
Chris Cant
I forgot to say thanks for this.
Let us know when the new Home Compostable certification logo
appears. I'm not sure if either of these pages has the new logo:
Chris
Penrith