Medium density fiberboard, or MDF, is one of the most widely used materials for furniture manufacture and is also popular in the construction industry. It’s relatively cheap, easy to manufacture into diverse shapes and its strength is much more predictable than solid timber. The problem is that MDF is a product of an age when efficient use of raw materials wasn’t a high priority, for producers or consumers, and that shows up when it comes to recycling. It’s not an easy material to reprocess; although the bulk of it is made up of wood particles it also contains significant amounts of adhesives, usually urea-based, and is often faced with various types of plastic. As a result of this most of it has traditionally been disposed of in landfills. It’s a bulky material, however, and while it usually deteriorates quite quickly it can take many years for the resin-impregnated wood to actually biodegrade. Carcinogens are also released in the process.
A lot of effort has gone into finding ways to recycle MDF, and several challenges have been identified. The main one is the adhesive which holds the product together; for many potential uses, including remanufacturing into new MDF, this must be removed. The easiest way to do this is by shredding the material and soaking it, to form a slurry, then heating it. It works, but uses large quantities of water and energy. UK company MDF Recovery Limited hope to make the process more efficient with a new ohmic heater they’ve developed specifically for MDF recycling; shredded MDF is soaked then an electric current is passed through it, resulting in rapid heating and breakdown with much less use of water. The recovered material is high enough grade to be manufactured into new MDF.
An alternative technology is the Micro Release process; this uses microwaves to break down MDF, and again it recovers wood fiber that can be remanufactured into fresh MDF. Both of these technologies are too new to judge how many times the material can be recycled before the fibers break down too much, but even a single reuse will add up to a significant cut in both landfill usage and wood consumption.
There are other options apart from reusing the wood particles for MDF. One of the simplest is just to shred the material then burn it, using the heat produced to generate energy for the recycling plant. Burning without energy recovery reduces the amount going to landfill but is wasteful, especially considering the potential uses for recovered particles. Another method now coming into use is to break down the MDF using the standard technique then compost it for agricultural use; this works best with MDF dust and is a good option for waste produced during the manufacture of MDF products. It does require a very high level of efficiency at removing the adhesive, to avoid the possibility of carcinogenic substances entering the food chain.
In 2004 over a million cubic meters of MDF was produced, and almost all of this is going to be disposed of at some point. Right now the majority goes to landfill, but with annual production continuing to increase this isn’t viable as a long-term solution. It’s vital that the new processing technologies are developed further and put into widespread commercial use; then perhaps MDF can be made as environmentally friendly as it is affordable and versatile.