recycling plastics

march 31 2008

A few months ago our neighbourhood became one of the very few test areas of recycling plastics.

We were very enthousiastic, because we want to do all we can to prevent pollution and useless waste.

That the container was too far away was a bit of a trouble, because it turned out that plastic tends to need quite some volume.
We found some ways to prevent shops to put more plastic on our groceries than absolutely needed and we created some ways to deal with the volume.

Now we're saving quite some money, because we're not needing to dispose of so much household waste anymore.

Two weeks ago the children went with school to the waste incineration facility to see what happens with our waste.

No word was spent on how plastics are recycled.
Luckily one of the boys wrote a paper about the subject a while ago, so they could present the subject at school.

We have strict rules for what needs to be in the plastic container and what not.
That's because the High Density Polyethylene is the plastic they want. That means: bags, bottles, films around food and some other products, and plastics like we know as Tupperware.

The first step in plastic recycling is sorting the usable and unusable plastics, followed by cleaning, drying, and a thourough control to remove the contaminations that are left.
Then the plastic is cut into small stripes and flakes.

These are transported into a large kind of barrel where pressure and heat ensure uniform melting.
Again a filtering process cleans the mixture.
Then it's pressed out of the barrel and immediately cut into granules.

These HDPE Granules are cooled and packaged.

The quality of the granules depends on three important features of the production process:
- the filtering. The cleaner the material is the better.
- the venting of the barrel, so unwanted gasses and moisture can disappear, leaving less bubbles.
- temperature in the barrel. Too low means that the mixture isn't melted evenly, too hot means the plastic can loose all structural integrity and becomes useless.

The HDPE Granules are used to make new plastic products, like garden furniture, plastic containers and packaging material.

It's fun that we found the best way of storing our waste plastic while talking about the recycling of it.
We now use a container with a lid that can be pushed open from the outside, but not from the inside.
Ofcourse the container is made from... HDPE Granules!

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