Material recovery facility

A material recovery facility is also known as materials reclamation facility, materials recycling facility or Multi re-use facility is a specialized plant that receives, separates and prepares recyclable materials for marketing to end-user manufacturers.

Generally, there are two different types: clean and dirty MRFs.

1. Clean MRFs

• A clean MRF accepts recyclable materials that have already been separated at the source from municipal solid waste generated by either residential or commercial sources.
• The most common ones are a single stream where all recyclable material is mixed or dual-stream MRFs, where source-separated recyclables are delivered in a mixed container stream and a mixed paper stream (including OCC, ONP, OMG, Office packs, junk mail, etc.).
• Material is sorted to specifications, then baled, shredded, crushed, compacted, or otherwise prepared for shipment to market.

2. Dirty MRFs

• A dirty MRF accepts a mixed solid waste stream and then proceeds to separate out designated recyclable materials through a combination of manual and mechanical sorting.
• The sorted recyclable materials may undergo further processing required to meet technical specifications established by end-markets while the balance of the mixed waste stream is sent to a disposal facility such as a landfill.
• A dirty MRF recovers between 5% and 45% of the incoming material as recyclables, and then the remainder is land filled or otherwise disposed.
• A dirty MRF can be capable of higher recovery rates than a clean MRF, since it ensures that 100% of the waste stream is subjected to the sorting process, and can target a greater number of materials for recovery than can usually be accommodated by sorting at the source.

How a Materials Recovery Facility Works

MRFs can vary in some respects in terms of the technology employed, however, a typical process would include something such as the process described below.

MRFs have customer vehicle scales and a yard that can accommodate a queue of trucks. Incoming haulers arrive at the MRF and dump the material onto the tipping floor. A front end loader or other bulk material handling equipment then drops 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 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, the material goes to a pre-sort station, where workers standing along with the conveyor spot and remove any trash, plastic bags or other mistakenly placed material and separate them for appropriate disposition. Large pieces of plastic or steel, including pipes and other large items, can damage the system or expose workers to the risk of injury.

Larger pieces of cardboard are then 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 the disk 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 co-mingled material. Glass containers can be separated from plastic containers by a density blower, then hammered into the crushed glass, known as cullet.

Remaining plastic containers may be sorted manually by workers on the conveyor line, or increasingly, optical sorters are 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, with finished bales weighing in the range of 1000 to 1500 pounds.