Skip to Main Content

What’s Old is New, What’s Green is You: A behind-the-scenes look at the recycling process

Illustration showing recycling process

Recycling process; by Max Tucker

If you are like most Marylanders, you probably already have a general understanding of recycling and why it is important. Charged with protecting the Chesapeake Bay, Maryland’s population is particularly engaged in environmental issues. It is no surprise, then, that recycling has increasingly become the norm here, with recycling rates climbing from less than 20 percent two decades ago to higher than 43 percent today. Every time you set out your bottles and cans at home or drop your paper in the bin at work, you play a crucial role in that success. Yet that is only where the story begins.

Behind the scenes, a complex network of people, equipment, technology and facilities works to recover and ultimately reinvest these materials into our economy. And while the concept of recycling is not new, it is constantly evolving, influenced by the products we use, advancements in technology, fluctuations in domestic and international markets, and shifting cultural perceptions of what constitutes “waste” versus “resource.”

It starts with collection
Depending on where you live, you either set out your recyclables at the curb or take them to a drop-off center. While that may seem simple, local governments put a great deal of thought into designing collection programs. Hauling contracts, collection frequency and even container sizes are all carefully selected to encourage optimum recycling behavior in light of local conditions.

Once collected, recyclables are typically trucked to a materials recovery facility. The purpose of this facility is to sort and prepare materials for their first re-entry into the market. At the facility, incoming recyclables are emptied from trucks and fed onto a maze of rapidly moving conveyor belts. The belts navigate a succession of sorting lines that remove each type of recyclable to a separate storage area.

Sorting it out
Sorting methods range from simple to cutting edge. For some tasks, there is still no substitute for human perception. Workers at an initial pre-sorting station often act as gatekeepers, scrutinizing the flow of incoming material and intercepting bulky or non-recyclable items that may otherwise damage expensive sorting equipment.

Screening equipment is used to remove certain materials by size and shape. For example, a disc screener is often used to separate cardboard. A disc screener contains rows of rotating discs; the larger cardboard pieces are buffeted upward over the spinning discs and out the other side, while smaller materials fall between the discs and continue on to the next sorting station. Additional screens may be used to separate various types of paper.

Containers must also be separated by type. A glass breaker contains rotating pieces of metal that crush and remove glass bottles and jars, while lighter plastic and metal containers bounce safely over the crushers and out the other side. Steel cans are separated with a magnet, and an eddy current—essentially a reverse magnet—repels aluminum cans to their holding area.

Plastic can be more complicated, as the containers must be further sorted by resin—or type—in order to be marketable. Some types of plastic may be removed by hand, while others may be separated with a higher-tech method called an optical sorter. An optical sorter has sensors that can detect subtle differences in materials’ color, reflectance and structure. When an item with the desired characteristics is identified, a precisely directed blast of air propels the item into a separate receptacle.

A delicate balance
Once the materials are separated, they are fed into balers, which compress the material into giant blocks held together with wire. The two outputs of a materials recovery facility are these bales of recyclables and the residue—left over material that is either non-recyclable or could not be effectively sorted. The operator of a materials recovery facility must constantly balance these two outputs.

Minimizing residue means sending less material to the landfill and returning more to the market. However, if too much non-recyclable material is included in the bales, they may not pass muster with quality-conscious buyers.

Increasingly, the quality or contamination rate of recyclables is a major determinant of whether the material can be sold, how quickly and at what price. Materials recovery facilities must tackle this issue while the stream of incoming material is constantly changing. One example is the trend toward flexible, lightweight plastic packaging as opposed to traditional packaging. (Think baby food in a plastic pouch rather than a glass jar.) These changes may have environmental upsides, such as using less material and requiring less fuel for transport, but they can also be more difficult to recycle.

Becoming new products
Once baled, the commoditized materials are sold and are likely to change hands several more times before they end up in the hands of a consumer. The process varies for each material. For example, a bale of plastic bottles may be sold to a broker, who then sells it to a plastic recycler. The recycler washes, shreds, further sorts and dries the material. The resulting plastic flakes are then sold to a manufacturer, who uses them as a raw material in the production of a product, such as carpet, clothing or new plastic bottles.

When recovery facilities and brokers market their baled materials, they look to maximize profit, taking into account the costs of getting the product to market. So, recyclables collected in Maryland may be recycled locally, elsewhere in the U.S., or even abroad.

A great impact
While recycling is complex and can even take materials across the world and back, the actions of individual Marylanders echo throughout that process.

When an individual makes the initial decision to place an item in the recycling bin rather than the trash, that decision, in the aggregate, ultimately influences the quantity and quality of recyclables on the market.

This in turn leads to environmental benefits that reverberate throughout the supply chain, such as reducing greenhouse gas emissions and conserving energy, resources and water.

By learning what is recyclable in your locality and recycling as much as possible, your positive impact on the recycling process can reach far beyond the curb.

Article by Kaley Laleker—Land and Materials Administration deputy director at the Maryland Department of the Environment. Appears in Vol. 21, No. 1 of the Maryland Natural Resource magazine, winter 2018.