Published: April 15, 2021 By

Recycling is a tricky process that takes practice and constant education since guidelines are often changing. According to EcoCycle, Boulder’s recycling company, there are some items that they see constantly contaminating their recycling machines. On-campus, the ROC sorts through recycling in order to send them to their longest and best use. Here are a couple of common contaminants and the reason why these items need to stay out of our recycling bins.

Plastic Bags

Recycling facilities cannot handle plastic bags because they jam the processing equipment and cause the entire recycling facility to shut down. Some recycling facilities have scheduled time every day dedicated to clearing out plastic bags from the machinery since this contaminant is so common and so damaging. It is predicted that some recycling facilities are losing $1000 per DAY because of these stoppages.

What you can do with plastic bags:

  • Reuse them!

    • Instead of getting new ones, use the ones you already have!

  • Recycle them at CHaRM in Boulder

    • Clean, dry, empty plastic bags can be recycled at Boulder’s Center for Hard-to-Recycle Materials located at 6400 Arapahoe Rd, Boulder.

  • Throw them into the landfill

    • Although these bags will sit in this landfill for years, it is a better option than clogging recycling equipment. The best option is to avoid plastic bags altogether!

Shredded Paper

This type of paper is too small to sort and the pieces fall between the cracks of sorting machines, stick to the belts, and make a mess on the floor. Compost shredded materials in your curbside bin rather than recycling them!  For shredded paper on campus, you can follow these guidelines.

Scrap metal

Pieces of metal of any size can cause extreme damage to recycling equipment. Similar to plastic bags, pieces of scrap metal can be taken to CHaRM in Boulder or to the Longmont or Nederland Recycling Drop-off Center where there are bins marked “Scrap Metal.”

Hazardous Waste

Paint, automotive fluids, car batteries, and pesticides must be taken to the Boulder County Household Hazardous Waste Facility. Hazardous waste also includes anything that can poison, corrode, explode, or burst into flame when handled improperly. Do NOT dispose of hazardous waste in the trash, down the drain, or onto the ground since all of these disposal methods could lead to health and/or environmental problems.

Non-recyclable plastics

Determining which plastics can be recycled can be tricky. Plastic lids, Styrofoam, and any other plastics not listed in EcoCycle’s recycling guidelines are not recyclable in your curbside bin. This is because stable, profitable markets do not currently exist for these materials.  Some are “Hard to Recycle”, but others are destined for the landfill.

Flattened containers

Single-stream equipment separates “flats” (usually paper) from “round” objects (usually containers. When containers are flattened, the equipment may mistakenly send them to the wrong side of the facility and contaminate the material that will be sent to the market.

Caps of Lids

  • Plastic bottles or jars

    • Empty all liquids

    • Screw cap back on and put it all in the bin

    • Large yogurt lids can go in the bin loose

  • Glass bottles or jars

    • Remove all metal and plastic lids from glass bottles and jars before recycling

    • Put metal lids into bin loose

    • Loose plastic lids go to the landfill


Before recycling bottles and jars, make sure to empty and rinse out all containers before throwing them in the recycling bin. This helps keep recycling facilities working more efficiently since they don’t have to stop and clean up sticky, smelly messes.

Frozen food boxes

Frozen food boxes are made from paper that uses a type of plastic resin to protect the food from freezer burn. Recycling facilities are unable to separate this plastic from the paper before it enters the pulping process.

Wrappers and packets

Since wrappers are made of a mix of materials such as plastics and aluminum, they cannot be effectively recycled at a recycling plant. Some companies are using candy and chip wrappers to create new products such as bags and home decor.

Ceramics, Pyrex Glass, Mirrors

At most waste facilities, ceramics, pyrex glass, and mirrors cannot be melted down. Broken plates, other broken ceramics, pyrex glass, and mirros should be thrown in the trash since they can contaminate the glass stream in recycling facilities. If your ceramic dishes, pyrex, and mirrors are reusable, donate them to a local donation place such as Goodwill!