Sunday, 1 April 2012

The question of contaminants in recycled plastic

Recyclers continue to struggle with contaminants in electronic waste and in consumer plastics according to Naomi Lubik in the Environmental Science & Technology journal in Plastic’s Polluted Burden: ES&T’s Top Policy Analysis Article 2011.

In Europe researchers found that every class of plastics was contaminated. Overall, the team measured levels of cadmium close to or slightly above the levels set by the directive, but mercury well below the target levels. Lead in some places was very high, occurring at up to 7800 ppm…..

Recycling programs in Europe take in items including refrigerators, computers, cell phones, toys, and medical devices.
The wide variety of incoming plastics, as seen in the photo above, can be difficult to sort. In some of the more advanced recycling plants, mechanical shredding gets the plastics down to fingernail-size pieces, which must then be sorted by weight or optical methods to pinpoint the plastic type…..

Recycling contaminated plastics means that hazardous substances will never completely disappear from the market.
“We spread contaminants into a variety of products,” says Martin Schlummer of Fraunhofer Institute for Process Engineering and Packaging in Freising, Germany. Schlummer works on methods to separate plastics and extract flame retardants. To get rid of contaminants, he says, “you should sort such plastics from e-waste and treat them separately.”  

Australians are among the highest users of new technology in the world. Waste from obsolete electronic goods, or “e-waste”, is one of the fastest growing waste types.

In practical terms e-waste includes items such as televisions, DVD & video players, stereos, power tools, desktop computers and laptops, computer keyboards, scanners, printers, fax machines, mobile phones and PDAs, kitchen appliances, and ink & toner cartridges – from which plastic is often extracted for recycling.

Such e-waste can have components containing lead, antimony, mercury, phosphors, beryllium, brominated flame retardants (BFRs), phthalates, cadmium or arsenic.

Although many recycling facilities operating in Australia routinely separate e-waste from other sorts of waste**, one has to wonder if there is any ability to ensure that no contaminants have been absorbed into the plastic being extracted. Given that items containing plastic only appear to be manually sorted for visible gross contaminants, before being mechanically processed and separated into plastic/non-plastic material which had been reduced to tiny segments along the processing chain.

The entire question is complicated by the fact that Information about the disposal and recycling of waste materials and products is variable in scope and quality with some jurisdictions not collecting data and others having different waste categories according to the National Waste Report 2010.

** Veolia Environmental Services Australia states:
Sims Recycling Solutions states that it:
dismantles a wide range of electrical and electronic products, ensuring all sensitive data is shredded to protect customer assets. Hazardous substances are recovered and disposed of in an environmentally friendly manner. Commodities such as metals, plastics and glass are then processed for recycling.
Recycling company 1800 E Waste states: Most electronic waste goes through a recycling system called a WEEE (Waste Electrical and Electronic Equipment), which not only recycles 95-98%, by weight, of all ewaste passed through it, but ensures that any data left on hard drives and memories are thoroughly destroyed too. 

■Picking Shed – first all the items are sorted by hand and batteries and copper are extracted for quality control.
■Initial Size Reduction Process – items are shredded into pieces as small as 100mm to prepare the ewaste to be thoroughly sorted. This is also where the data destruction takes place.
■Secondary Size Reduction – the small debris is shaken to ensure that it is evenly spread out on the conveyor belt, before it gets broken down even more. Any dust extracted is disposed of in an environmentally friendly way.
 ■Overband Magnet – using magnets, steel and iron are removed from the debris.
■Metallic & Non-Metallic Content – aluminium, copper and brass are separated from the non-metallic content. The metallic can then be reused and resold as raw materials.
■Water Separation – water is used to separate plastic from the glass content. Once divided all raw materials can then be resold.

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