A materials recovery facility (MRF) is a key component of residential and commercial single-stream recycling programs. A MRF (which is often pronounced like it rhymes with “turf”) receives commingled materials and uses a combination of equipment and manual labor to separate and densify materials in preparation for shipment downstream to recyclers of the particular recovered materials.
Learn more about MRFs and how they prepare materials for recycling.
What Is a Materials Recovery Facility?
Typical materials recovered at MRFs include ferrous metal, aluminum, glass, PET, HDPE, and mixed paper. There are two types of MRF: clean, which handles the contents of commingled recycling bins that consist mostly of recyclable materials, and dirty, which handles solid waste that includes some salvageable recyclable materials.
Alternate names: material recovery facility, material(s) reclamation facility, material(s) recycling facility
How Does a Materials Recovery Facility Work?
MRFs can vary in some respects in terms of the technology employed; however, a typical process would involve the following steps.
MRFs have customer vehicle scales and a yard that can accommodate a queue of trucks. Incoming haulers arrive at the MRF and dump the commingled material onto the tipping floor. A front end loader or other bulk material handler then drops it into a large steel bin at the start of the processing line. This bin is known as the drum feeder. Inside of the drum feeder, a fast-moving drum meters out the commingled material onto the conveyor at a steady rate while also regulating the density of the material on the conveyor so that it is not packed too tightly together.
From there, material goes to a pre-sort station where workers standing along the conveyor spot and remove trash, plastic bags, or other inappropriately placed materials and separate them for disposition. Large pieces of plastic or steel, including pipes and other large items, can damage the system or expose workers to risk of injury.
A wet MRF is a special type of dirty MRF that uses water to help separate and clean materials.
Larger pieces of cardboard are removed from the mixed material stream, pushed to the top by large sorting disks turning on axles, while heavier material stays beneath. Smaller sets of sorting disks may then remove smaller pieces of paper. As materials are separated, they are diverted to separate conveyors for accumulation and baling.
Powerful magnets separate steel and tin containers, while an eddy current separator is used to draw aluminum cans and other non-ferrous metals from the remaining commingled material. Glass containers can be separated from plastic containers by a density blower, then hammered into the crushed glass known as cullet.
Any remaining plastic containers may be sorted manually by workers on the conveyor line, or optical sorters may be used to identify different materials and colors. Air classification may be used to separate key plastics such as HDPE and PET.
Separated materials, other than glass cullet, are typically baled. The weight of the finished bales vary greatly according to the material in question and the capacity of the baling equipment; finished bales can weigh anywhere from 25 to 1,500 pounds.1
Clean MRFs vs. Dirty MRFs
A clean MRF can be differentiated from a dirty MRF in that it accepts commingled blue bin materials that contain mostly recyclables with some mistakenly included trash. A dirty MRF, on the other hand, processes household or commercial trash that most likely contains a low percentage of recyclables.
Dirty MRFs can capture recyclable materials that would have been missed because consumers or workers at a business placed it in the trash rather than in a blue bin. However, the dirty MRF can require considerably more manual labor for sorting and can result in the contamination of paper and old corrugated cardboard.
The recovery rate of recyclable material from a clean MRF is predictably very high, while the recovery rate from a dirty MRF is much lower, probably not more than 30%.2 Dirty MRF material is also much heavier, thanks to organic material in trash. It averages around 350 pounds per cubic yard when organics are not diverted, as opposed to 50 to 100 pounds per cubic yard of blue box material.3
Problems for MRFs
Even clean MRFs struggle with a variety of unrecoverable materials, especially plastic bags. And a big problem for dirty MRFs are large, potentially hazardous objects, which must be removed at the beginning of processing.
Unwanted materials increase the need for manual sorting, which in turn increases inefficiencies for MRF operators and ultimately for the communities they serve. Such problems are intensified in the face of declining markets and lower prices for the materials they sell, such as has been experienced in recent years due to tightening import restrictions by China.
Key Takeaways
- A materials recovery facility receives commingled materials and separates out and bales the recyclables.
- MRFs typically recover ferrous metal, aluminum, glass, plastics, and mixed paper.
- Clean MRFs handle the contents of commingled recycling bins that consist mostly of recyclable materials.
- Dirty MRFs handle solid waste that includes some salvageable recyclable materials.