A study was conducted to analyze the impact of incorporating post-consumer pizza boxes in the recovered fiber stream. More specifically, factors such as grease and cheese were primarily observed. The summary of the findings includes the following:
- The number of pizza boxes placed on the market in the U.S. annually is estimated to be 3 billion boxes equating to 600,000 tons of corrugated board. Pizza boxes represent 1.7% of the 35.9 million tons of corrugated containerboard produced in the U.S. annually.
- If all pizza boxes were recovered for recycling, they would represent approximately 2.6% of the OCC stream or 2.2% of the OCC and mixed paper stream combined.
- Pizza boxes currently found in the recycling stream have an average grease content of approximately 1-2% by weight level.
- Grease is hydrophobic and when pizza boxes approach a 20 wt% concentration of the furnish, grease interference with inter-fiber bonding begins to result in significant paper strength loss (~5%). At pizza box concentrations under 10%, paper strength loss is low.
- The strength loss as a function of “greasy” fiber and pre-consumer board was almost linear in the 0-20 wt% blend level.
- Cheese, comprised of fats and proteins, is hydrophilic and does not hinder hydrogen inter-fiber bonding of fibers. Cheese tends to solidify and get screened out during the pulping process.
To read the study in its entirety, see the attached file.