Styrofoam is 95% air. An EPS recycling machines removes the air, making the product 50-70 times smaller. Older methods of removing the air from foam were less efficient as they merely compressed the substance.
These use hydraulic pressure to compact the Styrofoam. This pressure is sufficient to remove the possibility that the foam will return to its original shape. This process does not use heat, and therefor does not produce smoke or odour. These hydraulic systems can accept many different type of foam without issue.
This system will heat Styrofoam in order to reduce its size. The final product is either a rope or block. The rope version of the foam requires some additional about for it to be stored, but both forms are weather resisntant. These thermal densifiers do require a considerable amount of electrical energy. They also produce a strong odour.
Screw Drive Densifers:
These use speed and pressure to reduce Styrofoam into solid blocks. Because of the use of pressure (rather than heat) there is no odour produced. The only disadvantage is that these machines cannot simultaneously process different densities of foam, though modern devices are more tolerant of this.
Hybrid densifer also exist, which combine the hydraulic and screw mechanisms.
An EPS recycling machine is a useful device. It will mostly go unseen by the general public, even as the public continues to use the Styrofoam with countless products. Though not traditionally seen as recyclable Styrofoam can now be processed to be reused and have minimal impact on the environment.
Recently it has been discovered that mealworms can digest Styrofoam, strongly suggesting an environmentally safe way of dealing with the product.