How is Paper and Cardboard Recycled?

Recycling Rules

What happens after mixed recycling gets tossed into your bin? Let’s walk through the recycling process for paper and cardboard:

1. Collection

Waste Haulers collect mixed recycling materials, also known as single stream, from homes and businesses. In Sioux Falls, there are over 20 licensed waste haulers, so you have a wide selection to choose from for who picks up your trash and recycling (see a list of local haulers). After the material is picked up by your hauler, it is brought to Millennium Recycling (If you don’t have a waste hauler you can also bring it directly to the public dropoff bin). All types of paper and cardboard are accepted in the single stream including Office Paper, Newspaper, Junkmail, Envelopes, Magazines, Inserts, Brochures, Catalogs, Phone Books, Paperback Books, Milk, Juice and Soup Cartons, Flattened Cardboard boxes, Brown Paper Bags, Paperboard Boxes, and Paper Egg Cartons. They must be clean of food waste without any plastic or metal add-ons (i.e. plastic newspaper bags, bubble liners, spiral binding, styrofoam, etc).

2. Sorting

At Millennium, the mixed recyclables are dumped into a huge pile and a team member checks to make sure no large, bulky items are in the mix that could damage the equipment or hurt employees (i.e. tree branches, car engines, etc). The materials are moved onto a conveyor belt where workers pull out plastic bags and other items that are not recyclable or might jam up the equipment (i.e. clothing, wire hangers, garden hoses, etc). Next, the material moves onto a machine with star-shaped, rotating discs called a “screen” that lifts out cardboard and separates it into a pile. A second screen then lifts out the paper. The remaining items (plastic, glass and aluminum) fall through the screens and continue onto the rest of the sorting process back on the conveyor belt. Now that the paper and cardboard have been separated, they are baled and transported to specialized paper and cardboard mills like Minnesota based Liberty Paper Inc or WestRock as examples.

3. Pulping

After the paper and cardboard arrive at the mill, they each get fed into a large drum that spins with water to form a slurry. A chain or rope usually hangs down inside the drum, catching material that is not fiber based, known as contaminants, to separate them out (string, tape, etc).

4. Cleaning

The slurry material, called “pulp”, then goes through many different filters to strain and strip out any other materials that need to be removed as well as soaked in a water tank where heavy items like metal sink to the bottom and lighter items like plastic float to the top to be removed. Examples of materials that need to be removed in the cleaning process include glues, tape, dyes and plastic windows (on envelopes for example).

5. Finishing

The clean pulp gets fed into a machine that heats, dries and squeezes any excess water out. It can now be formed into paper rolls to be used for new products like office paper or tissue paper depending on the quality, or formed into flat liner sheets for use in new cardboard or boxboard products, like cereal boxes.


For more detailed description of the process, check out Liberty Paper Inc’s diagram, it’s very informative!