The specification for the Materials Recovery Facilities (MRFs), which sort north Londoners’ recycling into the different individual materials includes pizza boxes as long as they are not heavily contaminated with grease or food. As most pizza boxes are likely to have oily residue, our current guidance says that they should not be included - paper/card stained with grease is listed under the ‘no’ section. However, we will shortly be updating this guidance because a small amount of grease is not a problem and as long as any separate polystyrene tray inserts are removed, pizza boxes can be recycled along with any other cardboard in the recycling.
The reason that cardboard contaminated with food and grease is a problem is because the food cannot easily be removed, so it means that when the cardboard goes for recycling it contains cardboard and food - manufacturers don’t want their cardboard to be mixed up with bits of old food. A lot of grease is a problem because it makes the fibres in the cardboard stick together so that it is more difficult for the cardboard manufacturers to separate the individual fibres for making into new cardboard.