Continuing along the path we have set regarding the life-cycle of this material, we have already seen the production, transformation and utilisation stages. We now find ourselves with a material that performed its function, but we'll see that positive gains can be made for the environment by appropriate management.
Waste generation level
As far as waste generation level is concerned, let us begin by introducing a term we have not used up to now but which will help us to rid ourselves of part of the misunderstandings pertaining to the contribution of EPS to municipal solid waste ("MSW") . The term is: visual pollution.
EPS is white and is exceedingly visible after its removal. EPS pieces, packaging, and above all, the largest packaging pieces which are very bulky when they are left at waste collection points. Large white pieces that can be recognized from a distance and which produce the effect of a lot of waste occupying considerable space in trash bins or that do not fit into them. This is visual pollution. It is not real pollution because EPS consists of 98% air. All the same, it does create confusion because it makes us think that on abundance of the material is produced and later thrown away.
If we look at the percentages of the different constituents of MSW, we will see that EPS makes up a tiny part of the total waste stream, contrary to what visual pollution might make us believe. Verification of these values is widely available and a good source of information of this type can be found at http://traumwerk.stanford.edu:3455/Symmetry/174
By examining these charts we can see that plastics in general only account for 7% of the MSW and that among plastics EPS makes up 1.5%of plastic waste and that this in turn means only 0.1% of all municipal solid waste.
Analysis of these figures show that the contribution of EPS to waste generation is really very small. Even so, the EPS industry and the plastics industry in general are actively working with local and national authorities to develop economically and environmentally feasible waste management policies.
The smaller and lighter a product is the less waste will be generated at the end of its useful life. In the last few years the EPS industry has made great efforts, and will continue to do so, to reduce the quantity of material used in their products by improving the initial properties and designs to minimize material use while optimizing product characteristics.
EPS products can be re-used in many applications. Outstanding among them is that of specially designed packing for multiple trips in manufacturing processes and product assembly.
Depending on the nature and origins of the material plastic waste, it may be necessary to submit them to selective collection, classification, grinding, washing, drying, additives and granulation before recycling. Waste from industrial and distribution packaging are relatively uncontaminated and homogeneous and the fact that they are unsullied means that mechanical re-cycling is feasible. Among plastics, EPS enjoys advantages in that it is easily recognizable and because it is mainly used to pack articles that do not contaminate it, like electric and electronic consumer goods. Another of EPS' advantages over other materials is that there are many options available for mechanical re-cycling.
Let's see what they are:
Manufacture of new expanded polystyrene parts:
By grinding EPS waste and adding it to production processes and by mixing on established percentage with new unused material. Depending on the applications new products, these may contain up to 20% recycled material.
Once EPS waste is ground and milled it IS used to mix with earth and hence improve drainage and aeration and contribute to enhanced plant growth. Many nurseries that use seedbeds and expanded polystyrene transport trays for seedlings take advantage these products for this use.
Auxiliary compost material:
Ground EPS products are used here to contribute to aeration of organic waste and it constitutes a valuable additive in preparing compost.
Adding to other building materials:
EPS waste is mixed, after being milled to different grain sizes, with other building materials for the manufacture of porous bricks, mortars, insulating plaster coatings, light concrete etc.
Waste from EPS is easily transformed by simple fusion processes to obtain the original material, compact polystyrene pellets. Pellets procured in this way can be used to manufacture simple objects like coal-hangers, pens, office materials etc. by injection molding.