Results from Collection and Recycling of Danish Mattresses
A partnership between several municipalities and companies is working to promote the separate collection and recycling of mattresses. The partnership has tested the collection, automatic dismantling and mechanical recycling of used mattresses from Copenhagen, Hillerød, Odsherred and Vejle.
The methods tested show potential to recycle metal, PUR foam and textiles into secondary raw materials of high quality.
The results have recently been published in a series of reports, which were presented in a webinar on 2 June 2022.
Great potential but also barriers
The results show that there is great potential for collecting mattresses for recycling at the country's recycling stations.
It is also possible in some places to collect the mattresses directly at the households, e.g. in connection with bulky waste collection.
Mattresses must be completely dry before they are suitable for recycling since handling wet mattresses is associated with fire hazard and increased bacterial growth. In addition, wet mattresses are unsuitable for the rebonding process used by mechanical recyclers, as the moisture prevents effective binding of foam granules.
Used mattresses must therefore be collected in closed containers and from covered bulky waste collection points.
There are ongoing experiments, e.g. in the Netherlands, with distribution of plastic covers to protect used mattresses from water during collection. This method has not been tested by the partnership.
- In the City of Copenhagen, 4.1 tonnes of mattresses were collected from Sydhavn Recycling Centre during a trial period of 6 weeks.
- In a parallel trial of 10 weeks, 8.5 tonnes of mattresses were collected directly from households at covered bulky waste collection points.
The collection trials included both box-spring mattresses and soft mattresses without a wooden frame.
Results from the processing trial at RetourMatras show that the box-spring mattresses are unsuitable for automatic dismantling due to the risk of fire and the material composition of the mattresses. Instead, box-spring mattress composition indicates that crushing of the mattresses and subsequent separation of wood and metal via scanners and magnets could still achieve a sorting rate of over 68 %.
The soft mattresses collected in the trial were, on the other hand, highly suitable for RetourMatras’ recycling method. The results showed up to 80 % recycling of the soft mattresses with the RetourMatras method compared to the 22 % achieved with the current treatment method. This gain is attributed to the large amount of PUR foam (up to approx. 41 %) and textiles (up to approx. 14 %) which can be recycled if the soft mattresses are collected separately.
Scaling the results to the entire City of Copenhagen means that more than 500 tonnes of soft mattresses could be collected for recycling each year. However, these figures are associated with some uncertainty.
The Danish company BPI A/S has also carried out recycling tests of mechanically sorted post-consumer PUR foam from mattresses. Driven by the positive results, BPI A/S has chosen to develop a new product based on post-consumer PUR foam. Input to this fraction is imported from the Netherlands while BPI is waiting for a Danish solution, which would make it possible to purchase Danish post-consumer mattress foam in sufficient quality. The company claims that it could potentially buy all post-consumer PUR foam from the Danish market in the future.