George W. Bailey / Shutterstock.com Paperboard Put in Garbage George W. Bailey / Shutterstock.com Break Down Boxes It’s easier for sanitation workers to handle and sort boxes that are broken down. It’s also easier for recycling equipment to identify paper-based material if it’s flat. Make sure to break down your boxes. Soiled Paperboard Is Not Recyclable Wet or soiled paperboard should be thrown away or composted because food residue and grease contaminates recycling. If only part of the paperboard is soiled, remove it and recycle the rest. Cereal & Cracker Bags Are Not Recyclable Cereal bags or box liners are generally made of HDPE (High Density Polyethylene), which is not recyclable. Find out what you can do with cereal box liners. Frozen Food Boxes Contain Plastic Frozen food boxes are made from paperboard but also contain a layer or two of plastic to help preserve their contents. Find out what to do with frozen food boxes. Milk and Juice Cartons Contain Plastic Milk and juice cartons are made from paperboard that has been lined with plastic to prevent liquid from leaking through. Find out what to do with milk and juice cartons.