My local council now takes most types of plastic bottles, pots, tubs and trays in the recycling bin. But they specifically exclude black plastic containers.
Is there a reason for this? Why can't black plastic be recycled in the same way as other coloured plastics? Does it depend on what sort of plastic it is made from?
From e.g. the Severnwaste recycling company (UK):
Plastic items are sorted by optical scanners which use the reflection of light to identify the types of plastics. Black plastic doesn’t reflect light, so can not be seen and sorted by the scanners and could end up contaminating other materials such as glass bottles. Microwave food trays which are normally black are also made of a special type of plastic which can not be easily recycled.
But in a forum post on TheRubbishdiet.com Joseph Kennedy from the PlasticExpert blog writes:
... in July (2014), Sainsbury’s and M&S began working together to alter the properties of the polymer to make it known to infra-red sorting technologies. So within a year we can hopefully expect to see this kind of plastic recyclable. This isn’t to say your council can’t recycle it.
They can, they just choose not to. The councils earn rebates on the materials they sell, which in turn helps pay for the council workers etc. Black plastic is the least valuable (that’s why your bin bags are black), and the reason is simple.
You can dye clear plastic black, but you can’t dye black plastic clear.
Black plastic is very low value, so your black food trays, bin bags, pvc guttering pipes etc, most often wont get recycled because they have little value on the other end of the market. It’s a money driven industry, like everything else.
The way in which the plastic is colored black makes a difference. From Recyclability of black plastic packaging at Wrap.org:
The majority of black plastic packaging is coloured using carbon black pigments which do not enable the pack to be sorted by the optical sorting systems being used widely in plastics recycling. As a result, black plastic packaging commonly ends up as residue and is disposed of in landfill or recycled into lower value materials where polymer sorting is not required.
WRAP has worked in partnership with key players in the retail supply chain to improve the recyclability of black plastics and prevent these materials from going to landfill.
This work was carried out in three phases and based on the results of this work, it is recommended that detectable black colourants be used as a viable option to carbon black pigments in the manufacture of black packaging such as amorphous polyethylene terephthalate (APET), crystallised polyethylene terephthalate (CPET), polyethylene (PE) and polypropylene (PP) packaging.
By selecting a detectable black colourant that enables the polymer to be detected by optical sorting systems the packaging supply chain can enable black plastic packaging to be recycled into a high quality, high value material which can substitute for virgin plastic in the manufacture of new items, and benefit the environment as well as the financial viability of mixed plastics recycling.
That last page has more detailed (technical) information.
Where I live, black plastic is recycled after hand sorting. Perhaps that costs too much where you live. The only plastic that is not recycled is red meat bags. They are a bio hazard, so no hand handling.
I think it's pure laziness. Before our city (Bloomington, MN) took over our trash collection we could recycle black plastic. I don't know what the previous (private) recycling company did with it but it was on their list of acceptable materials. When I called our city to ask why they didn't want black plastic, I was told it was because the machines couldn't read the symbol. That tells me the government is too lazy to hand sort and/or they are too overpaid to deal with such a mundane job. I don't know why the trays need to be black anyway. They put the dyes in to make the food look more colorful-that is silly. Clear is just fine.
