Plastics Recycling

Plastics Recycling

Significant amounts of resources, particularly fossil fuels, are required in the manufacture of plastics, to provide energy for manufacturing and as a raw material.

The advantages of recycling plastics are:

• Reduction in energy consumption
• Conservation of non-renewable fossil fuels as the production of plastic uses 8% of the world’s oil production.
• Reduction of solid waste being landfilled
• Reduction in emissions of nitrogen oxide, sulphur dioxide and carbon dioxide.

A report on the production of carrier bags made from recycled rather than virgin polythene showed that the use of recycled plastic resulted in the following:

• Reduction of energy consumption by two thirds
• Production of only a third of the sulphur dioxide and half of the nitrous oxide
• Reduction of water usage by nearly 90%
• Reduction of carbon dioxide generation by two-and-a-half times (source: Waste Watch)

The Different Types of Plastic:-

To make sorting and thus recycling easier, there is a standard marking code to help consumers identify and sort the main types of plastic.

• These types and their most common uses are:
• PET – Polyethylene terephthalate – Fizzy drink bottles and oven-ready meal trays
• HDPE – High-density polyethylene – Bottles for milk and washing-up liquids
• PVC – Polyvinyl chloride – Food trays, cling film, bottles for squash, mineral water and shampoo
• LDPE – Low density polyethylene – Carrier bags and bin liners
• PP – Polypropylene – Margarine tubs, microwaveable meal trays.
• PS – Polystyrene – Yoghurt pots, foam meat or fish trays, hamburger boxes and egg cartons, vending cups, plastic cutlery, protective packaging for electronic goods and toys
• OTHER – Any other plastics that do not fall into any of the above categories. An example is melamine, which is often used in plastic plates and cups.

Degradable Plastics:

These are oil based and break down to smaller fragments, however there is always a residue and the plastics do not break down into carbon and water alone.

Biodegradable Plastics

These are capable of undergoing decomposition into carbon dioxide, methane, water, inorganic compounds or biomass.

Biodegradable plastics should break down cleanly, in a defined time period, to simple molecules found in the environment such as carbon dioxide and water.

Compostable Biodegradable Plastics

These must demonstrate that they biodegrade and disintegrate in a compost system during the composting process (typically around 12 weeks at temperatures over 50 degrees centigrade).

Disposal of these sorts of plastics

Biodegradable and degradable plastics will not degrade effectively in a landfill site and could potentially hinder the quality of recycled plastic if they enter the plastic recycling system.

Disposal of these sorts of plastics

Biodegradable and degradable plastics will not degrade effectively in a landfill site and could potentially hinder the quality of recycled plastic if they enter the plastic recycling system.

How Is It Recycled?

Collection – Research produced by Recoup (RECycling Of Used Plastics), the UK Plastic Bottle Recycling Survey 2006, includes data from all 471 UK local authorities.

The research found that 86% of all local authorities in the UK now offer the facility for plastic bottle collection, and there has been an increase by 16% overall of the actual collection schemes since 2004.

Plastic process scrap recycling –

Process scrap represents some 250,000 tonnes of the plastic waste in the UK, and approximately 95% of this is recycled. This is usually described as reprocessing rather than recycling, as it is polymers left over from production runs. This is relatively economical and simple to recycle, as the material tends to be uncontaminated and there is a regular and reliable source available.

Post-use plastic recycling –

This is plastic material arising from products that have already undergone a first full service life prior to being recovered.

Mechanical recycling –

Mechanical recycling of plastics refers to processes which involve the granulation of waste or the shredding of it or melting. This material must be sorted prior to mechanical recycling, after which it is is either melted down and moulded into a new shape, or melted down after being shredded into flakes and then processed into granules called regranulate.

Chemical or feedstock recycling –

Feedstock recycling refers to plastic recovery techniques to make plastics, which break down polymers into their constituent monomers, which in turn can be used again in refineries, or petrochemical and chemical production.

Problems/Issues

Technically, almost all plastics can be recycled, but it is the collection, infrastructure and low market demand which create the barriers to the recycling of some types of plastics.

Yogurt pots, for example, are usually made from polystyrene or a blend of different polymer types.

These have a very different structure and composition to the PET, HDPE and PVC plastics used for bottles, and applications and market demands for these is limited.