Municipalities and organisations around the world are facing a growing problem in disposal and recycling of EPS foam packaging and products. EPS foam (Encapsulated Poly-Styrene) packaging is a highly popular plastic packaging material which finds wide application in packaging of food items, electronic goods, electrical appliances, furniture etc due to its excellent insulating and protective properties. EPS foam (also known as polystyrene) is also used to make useful products such as disposable cups, trays, cutlery, cartons, cases etc. However, being large and bulky, polystyrene take up significant space in rubbish bins which means that bins becomes full more quickly and therefore needs to be emptied more often.
Polystyrene is lightweight compared to its volume so it occupies lots of precious landfill space and can be blown around and cause a nuisance in the surrounding areas. Although some companies have a recycling policy, most of the polystyrene still find its way into landfill sites around the world.
Environmental Hazards of EPS Foam
While it is estimated that EPS foam products accounts for less than 1% of the total weight of landfill materials, the fraction of landfill space it takes up is much higher considering that it is very lightweight. Furthermore, it is essentially non-biodegradable, taking hundreds perhaps thousands of years to decompose.
Even when already disposed of in landfills, polystyrene can easily be carried by the wind and litter the streets or end up polluting water bodies. When EPS foam breaks apart, the small polystyrene components can be eaten by marine organisms which can cause choking or intestinal blockage.
Polystyrene can also be consumed by fishes once it breaks down in the ocean. Marine animals higher up the food chain could eat the fishes that have consumed EPS, thus concentrating the contaminant. It could be a potential health hazard for us humans who are on top of the food chain considering that styrene, the plastic monomer used in manufacturing EPS has been classified by the US National Institutes of Health (NIH) and the International Agency for Research on Cancer (IARC) as a possible human carcinogen.
Styrene is derived from either petroleum or natural gas, both of which are non-renewable and are rapidly being depleted, creating environmental sustainability problems for EPS.
Trends in EPS Foam Recycling
Although the Alliance of Foam Packaging Recyclers have reported that the recycling rate for post-consumer and post-commercial EPS in the United States have risen to 28% in 2010 from around 20% in 2008, this value is still lower than most solid wastes. According to USEPA, auto batteries, steel cans and glass containers have recycle rates of 96.2%, 70.6% and 34.2% respectively.
Because it is bulky, EPS foam takes up storage space and costs more to transport and yet yields only a small amount of polystyrene for re-use or remolding (infact, polystyrene accounts for only 2% of the volume of uncompacted EPS foams). This provides little incentive for recyclers to consider EPS recycling.
Products that have been used to hold or store food should be thoroughly cleaned for hygienic reasons, thus compounding the costs. For the same reasons, these products cannot be recycled to produce the same food containers but rather are used for non-food plastic products. The manufacture of food containers, therefore, always requires new polystyrene. At present, it is more economical to produce new EPS foam products than to recycle it, and manufacturers would rather have the higher quality of fresh polystyrene over the recycled one.
The cost of transporting bulky polystyrene waste discourages recyclers from recycling it. Organizations that receive a large amount of EPS foam (especially in packaging) can invest in a compactor that will reduce the volume of the products. Recyclers will pay more for the compacted product so the investment can be recovered relatively easier.
There are also breakthroughs in studies concerning EPS recycling although most of these are still in the research or pilot stage. Several studies have found that the bacteria Pseudomonas putida is able to convert polystyrene to a more biodegradable plastic. The process of polystyrene depolymerization – converting polystyrene back to its styrene monomer – is also gaining ground.