Green Tips: What’s compostable?

By: J. Harlan Ritchey

Food waste is Penn State’s largest waste stream, so nothing makes a bigger contribution to sustainability than composting your food waste. Did you know that sorting your compost is as
important as sorting your recycling? Let’s look at what we should and shouldn’t put in the green composting bins.

Food waste: YES
This includes fats, oils, fruit pits, shells, dairy, meat, bones, peels, and coffee grounds. You may have heard that things like meat and bones aren’t compostable. That’s true for little compost piles like the ones in home gardens where there isn’t enough mass and heat to break down tough organic materials. But Penn State’s enormous composting facility handles them with
ease. Put them in the green bin.

Paper plates and paper cups: IT DEPENDS
If they have a coating of wax or plastic: NO. (Milk and dairy cartons fall into this category.)
If they are made of more than one material: NO.
If they are uncoated, then YES, compost. (You can test the item by scratching it with your fingernail to see if any coatings scrape off.)

The Green Team gets asked about these a lot. The clear plastic Starbucks cups are 1) Not compostable and 2) Not recyclable—they are the wrong kind of plastic. They have to go
in the trash.

Utensils marked as “biodegradable” (made from bio-plastic or “eco-plastic”): YES
Bio-plastics are made from plant materials like corn starch instead of petroleum. You may see websites warning you that “biodegradable” does not mean the same thing as “compostable.” But similarly to the case of meat and bones, this warning mainly applies to small composting piles at home. Penn State’s industrial-scale composting operation will break them down with no problem. Just make sure they’re marked as such.

Paper towels, paper napkins, paper tissues If it has food waste on it: YES
If someone blew their nose on it: YES (I know it’s gross, but someone once asked. Yes—you can compost your tissues!) If they are soiled with cleaning chemicals: NO.

Pizza boxes made of paper/cardboard: YES
It’s OK if the box is greasy or soiled. Of course pizza crusts are compostable too. But throw away any little sauce or condiment containers. They’re not compostable.

Food containers with coatings, or food containers of mixed materials: NO

Coffee filters and tea bags: YES

Newspaper: NO (dry newspaper goes in the recycling bin for mixed office paper)

Wooden stirrers, toothpicks, etc.: YES

Here’s the official website from the Sustainability Institute:
That’s a lot! Still have questions? Email the Green Team at and we can answer it. We can also let you know how to purchase compostable items for your next event. A
representative can even come to your event to show your guests how to compost!

Harlan Ritchey
Engineering Library
Co-chair, Green Team