Nowadays, recycling centers as well sort out non recyclables that may have accidentally gone in the recycling bin. Frequently, people will accidentally put non recyclables in the recycling bin such as scrap wood, dirty cardboard/paper (Including pizza boxes), chip bags, etc.
For bagged waste, some recycling companies don’t even bother opening bags to check what is inside, they just throw them in the garbage no matter what is inside. However, some recycling companies open up waste bags in the recycling to see what is inside, if it contains a lot of non-recyclables the whole bag is usually sent to garbage; or if it contains all or mostly recyclables, the contents will be moved to the next stage of sorting. The plastic bag is either thrown away or recycled.
But let’s say you threw a dirty pizza box in the recycling. If it passes sorting, it will mess up the recycling process and the vat full of paper may have to be discarded; wasting all the paper. But if it was detected in sorting, it will be automatically moved to garbage.
Heavy metals are not supposed to be thrown in municipal recycling; however if it ends up in the recycling, it will be moved to the correct recycling for scrap metals.
Avoid accidentally getting plastic bags or fabric in the recycling, as those materials may tangle the machinery; causing more maintenance required for the recycling machinery.