Expanded polystyrene (EPS) foam, commonly known as styrofoam, the ubiquitous lightweight material used in packaging of electronic devices, food items and electric appliances, is popularly used because of its water and heat resistant properties. These properties likewise make it a preferred material for disposable food containers such as bowls, plates and coffee cups.
Due to its popularity, the global demand for EPS foam and its production is steadily increasing. According to GBI Research, the global demand for both polystyrene and EPS increased to 14.9 million tons in 2010 from 13 million tons in 2000.1 This is expected to further swell to 25 million tons by 2022, 1.7% of which, or close to 400,000 tons coming from the Middle East.
The increase in EPS production necessitates intensified recycling efforts. After all, a greater supply of EPS would result to more polystyrene waste, which, when disposed of in landfills take up significant space because of its bulk. Furthermore, because of its light weight, it can easily be blown away and litter streets and water bodies, and clog storm drains. Being non-compostable and essentially non-biodegradable, it would take hundreds if not thousands of years for EPS to decompose.
The technology to recycle polystyrene already exists and recyclers have been producing goods from recycled polystyrene for years. One of the reasons why polystyrene waste recycling is not very popular, even among recyclers, is the high cost associated with transporting the waste because of its volume to weight ratio. A truckload of EPS foam actually contains very little polystyrene, with 95-98% of its content being air.
The cost can be lowered considerably by reducing the volume of the waste, preferably at the point of origin, before transporting to recycling facilities. Volume reduction equipment offered in the market include balers, compactors and densifiers – these terms are sometimes used interchangeably by manufacturers – and the main differences in their processes are as follows:
1. Baling
Balers use hydraulic ram to compact EPS waste either vertically (from above) or horizontally (from the sides). The resulting bales are tied with a strap or twine to keep them together and for easier handling and transport.
2. Cold compaction
The volume of EPS is reduced without using heat. EPS waste is fed to a pre-breaker where it is broken into flakes of roughly 1 to 2 inches in size. Using an auger or screw compactor, it is then compacted hydraulically into “logs” or blocks, achieving a reduction in volume of up to 98%. The compacted polystyrene can be broken into size or transformed into pellets.
3. Thermal densification
Thermal densifiers such as StyromeltTM use heat to melt EPS and liberate trapped gases. The melted resin is then allowed to cool into briquettes or strands. This process achieves a greater compaction rate than most hydraulic compactors and results to a product that is sterile. There is, however, the issue of the release of vapours in the workplace and the smell created once EPS is heated. Most manufacturers resolve this by installing air filters on the equipment.
For companies, organizations or communities that receive and dispose of large quantities of EPS annually, buying or at least renting a volume reducing equipment could be a worthwhile investment. With reduced volume, garbage skips need to be emptied less frequently, reducing labor and transportation costs. As the oil prices and demand for recycled polystyrene products increase, so does the price for compacted EPS.
Although the prices may vary depending on the quality, compacted EPS could sell at £350 (US$530) per ton, with some recyclers willing to pay more for large quantities.2,3 Some recycling equipment suppliers or leasers even buy the compressed product for a competitive price, easing the need to find a separate recycler to deal with.
Being thermoplastic, compressed polystyrene can be melted and remolded to different plastic products and recyclers are finding innovative ways to do just that. It has been fashioned into CD cases, coat hangers, picture frames, toys and office supplies such as pens, stapler bodies and rulers.
Recycled EPS is also utilized to manufacture wood-alternative products such as interior decorative moldings.4 Such products are comparable to softwood but have the advantage of being both water- and mold-resistant, and of being impervious to rotting and decay.
Crushed polystyrene can be used as aggregates to produce lightweight concrete. Rastra, a company based in Arizona, USA, produces Insulated Concrete Forms (ICFs) using 85% recycled EPS and 15% cement.5 ICFs are hollow foam blocks that are stacked and filled with concrete to form building walls.
Homes and buildings built with ICFs are more sound-proof, and provide greater thermal insulation, making cooling and heating equipment more efficient. In South Africa, a new patented formula is being used to manufacture building panels from waste polystyrene, and plans are underway to build one million homes using the said panels.6
Recycling polystyrene certainly shows great promise and more ways of utilizing recycled polystyrene will likely be discovered in the future. Hopefully, the promise of greater profit, not to mention a cleaner planet will encourage companies, organizations and governments to step up polystyrene recycling efforts.
References
- Polystyrene and EPS market expected to grow at a healthy rate of 5.6% from 2010-2020, Plastemart.com, last modified February 14, 2013,
- Recycled-EPS Interior Molding, BuildingGreen.com, accessed July 30, 2013, http://www.buildinggreen.com/auth/article.cfm/2007/2/1/Recycled-EPS-Interior-Molding/
- ICF – Insulated Concrete Forms/Compound ICF, Rastra, accessed July 31, 2013, http://www.rastra.com/
- Building a million houses out of waste, Green Times
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