I feel guilty every time I order pizza. Not because I can polish off an entire large in one sitting though. It’s because you can’t recycle pizza boxes. Every takeout order is a huge waste of cardboard. Or so I thought. A new study says we actually can salvage that greasy, cheese-covered packaging. So long as we get rid of all the pizza inside.
And that’s definitely not a problem.
The packaging supplier WestRock has released a new report (that we came across at Sierra Club) examining the long-held common wisdom that pizza boxes can’t be recycled. The belief has always been that leftover grease and cheese could “interfere with inter-fiber bonding” during the recycling process. That would result in paper strength loss, making the new product unusable. The company put that belief to the test to see if “grease or cheese contamination levels typically associated with pizza boxes impact finished product quality.”
Grease is hydrophobic; it tends to repel or fail to mix with water. “When pizza boxes approach a 20 wt% concentration of the furnish,” the grease interferes with inter-fiber bonding. That results in significant paper strength loss. But at concentrations under 10 percent, “paper strength loss is low.” And WestRock discovered “pizza boxes currently found in the recycling stream” have an average grease content of approximately one to two percent by weight level. That’s easily within the range that can be successfully recycled.
However, cheese, comprised of fats and proteins, is hydrophilic. It mixes with water, so cheese does not hinder the inter-fiber bonding that is necessary. Mozzarella solidifies during the pulping process and gets screened out.
Combined with what they learned about the impact of grease the results are more than encouraging:
“The general conclusion of this work is that the strength loss of the resulting product made with recovered fiber that incorporates post-consumer pizza boxes should be minimal at typical levels of grease expected to be received in a recycling facility (<2%) and when included in the recovered fiber at expected levels of <3% of furnish. The addition of small amounts of cheese will not impact the fiber bonding in a negative way. It is expected that the larger chunks of cheese will be screened out of the process. Therefore, there is no significant technical reason to prohibit post-consumer pizza boxes from the recycle stream.”
As long as you aren’t putting heavily damaged boxes full of grease into recycling you should be fine.
WestRock reports the U.S. uses three billion pizza boxes every year. That equal 600,000 tons of corrugated board. It would be much better if all that cardboard didn’t end up at the dump.
Especially because then I wouldn’t have to feel guilty about ordering a pie. Just about how much of it I eat.
Featured Image: Sony