Did you know that the love for pizza runs deep in America, with approximately 43 million people savoring at least one slice daily? This beloved Italian-inspired dish isn’t just a culinary delight and a powerhouse contributor to the US economy, adding $47 billion annually. Around a third of the pizzas arrive in corrugated cardboard boxes at our doors.
However, the abundance of pizza boxes poses a challenge. Despite their ubiquity, these boxes, like many food containers, face recycling hurdles due to the residues they carry, notably grease and cheese. These residues, termed FOGs (fats, oils, and greases), stubbornly resist removal, rendering the boxes unsuitable for recycling.
When it comes to pizza boxes, materials and safety are top priorities. Crafted from sturdy, single-wall C-flute uncoated corrugated cardboard, these boxes are designed to handle even the heaviest pizzas while maintaining their heat during transport. The corrugated material absorbs grease and liquids, ensuring the pizza stays fresh.
Corrugated pizza boxes come in various styles and sizes, from traditional to innovative designs, including Kraft/Kraft, White/White, and 100% recycled Kraft board. They range in size from 6 to 30 inches and feature different flute designs (B, D, E, or F), meeting FDA requirements for food contact packaging. Customization options include different printing levels, from 1 or 2 colors flexo printed after the board is corrugated to 4-color preprint before the board is corrugated. Some boxes even include single-face inserts for better recyclability, acting as a physical grease barrier.
Researchers at Idaho National Laboratory (INL) and pizza enthusiasts are working to solve this pizza box recycling problem. Their recent study showcases a method to decontaminate cardboard using material separation capabilities.
This innovative project, funded by the Defense Advanced Research Project Agency (DARPA) ReSource Program, aims to separate grease, cheese, and other contaminants from pizza boxes. The ultimate goal? To convert common plastics and other waste into edible macronutrients and valuable items, reducing the need for risky supply runs on the battlefield.
Aaron Wilson, the principal researcher for the experiment, explains, “Material separation will be important for reducing waste across the energy and defense industries. To make specific separations possible, we need to first prove the overall concept of material separations, which is what this study accomplished.”The team developed an experimental system using dimethyl ether (DME), an eco-friendly chemical, and a lot of pizza. The system comprises two vertical stainless-steel reactors and a holding tank—the reactors separate liquids from solids and the solvent from the liquids. The holding tank stores the solvent until the experiment begins.
The process involves loading the contaminated cardboard boxes into the first reactor, adding the solvent, and mixing it with the cardboard boxes. This triggers a chemical reaction that extracts the contaminants from the cardboard. Once cleaned, the solvent is drained into the lower reactor, where the FOG contaminants, water, and salts are concentrated as crystallized solids. These can then be easily collected.
This extraction process is a significant improvement over standard water washing methods. Unlike water washing, which results in a large volume of wastewater containing a diverse mix of contaminants, the DME extraction process operates in a closed loop that recycles the DME solution to clean new waste items. This process can be scaled to any size.
The success of this case study could pave the way for future projects that convert waste into reusable materials, including the DARPA-funded project on repurposing military waste.
A lightweight system is crucial as most military cargo must be transported overseas and across rough terrain. The team is now identifying components that could be eliminated or replaced to reduce the reactor system’s weight.
As Lacey puts it, “INL started with this pizza box case study because most people care about properly recycling food waste. But ultimately, this research has so many possible applications for national security and a net-zero future.”
