A 45 mm trammel removes glass and a 170 mm trammel removes newspaper, paper, card, plastic and metal. Plastic, metal, cardboard and paper are further classified by ballistic separators. Dump trucks deliver mixed recyclable materials to the facility and stack them on the ground. The driver ensures that there are no large objects, such as a car engine, in the mix.
MWP is a single-bin system in which the consumer places all garbage and recyclable materials in a container without separation. This material then goes to a sorting facility to collect recyclable materials. In our previous blog post on single-stream recycling, we discussed how a material recovery facility (MRF) works. These facilities use a combination of machinery and human hands for sorting.
A separate conveyor system moves the material to a different area on site, where it is ground into coarse-grained sand for shipment to glass recyclers. There is also less potential contamination from recyclables (for example, leftover liquids don't spill onto paper and broken glass pieces don't mix with other items). Drum Feeder A mechanical gripper grabs a handful of material from the tumbling floor and drops it onto a rotating drum, which evenly distributes recyclable materials on a conveyor belt. In this city, which will remain nameless, there is a lack of transparency in the local dirty MRF, and recycling processes and rates are unknown.
Multistream facilities can sometimes be retrofitted to process mixed recycling, or some waste management companies consider building a single-flow MRF to make financial and administrative sense. In newer recycling plants, infrared sensors separate different types of plastics based on the different types of light they reflect. There, a largely automated system of conveyors, screens, magnets and lasers separates materials so that they can be sold to metal and plastic recyclers and paper mills. For the purpose of this blog, recovery rates are the percentage of materials that enter the facility and are diverted to recycling.
The most annoying aspect of recycling and one of the biggest obstacles to its widespread adoption is having to separate paper, glass and plastic before they reach the curb. A large drum rotates waste to separate all fine materials, such as dirt and dust, and organic materials, such as food waste, that would contaminate recycled materials. For example, North Carolina has a “dual flow MRF” network, where two or more recycling streams are fed separately to the facility. Many residents adopted dirty MRF as their primary recycling option, although curbside and drop-off recycling was available.
While the system is not perfect, its high-speed operation can cause contamination from broken glass, the simplicity of it means that homes recycle more. Hopefully, as a Cleantech Rising reader, separate trash from your recyclables and place them in the correct bins.