Paper isn't always reyclable. Case in point: shredded paper, which mucks up recycling machinery. View Full Caption Flickr/Marc Falardeau

LINCOLN SQUARE — Remember when learning the rules of recycling was as simple as ABC, or PPA — paper, plastic and aluminum?

Brace yourselves, folks: Plain old paper isn't always recyclable.

The trash might seem an undignified repository for a Nobel Prize-winning novel, but that's where hardcover books belong. Can't bring yourself to dump Shakespeare in with the coffee grounds and baby wipes? Allow us to recommend donating them to a Little Free Library.

The prohibition on hardcovers is just one of the forehead-slap discoveries we made scrolling through the city's new recycling website.

After years of focusing on simply rolling out the Blue Cart recycling program citywide, the city's Streets and Sanitation Department now is turning its attention to better educating residents on the finer points of what's recyclable versus what's garbage, spokeswoman Jennifer Martinez said.

Paper, for example, would seem like a no-brainer, but there are several exceptions.

If you've been dutifully shredding bank statements, credit card bills or any other document that contain information remotely ripe for identity theft, the resulting confetti should not be tossed into a blue cart.

All those bits of crosscut paper wreak havoc on the machinery at recycling plants, Martinez said.

For those who can't bear the thought of landfills clogged with the slivered fragments of everyone's financial records, Martinez has two suggestions.

One: Empty the contents of your shredder into a paper bag and seal it before placing the bag in the recycling bin.

We know, we know, Streets & San just told everyone that recyclables should be loose.

That's why Option Two is preferred: Take your confidential papers to a shredding service (FedEx, for example, charges 99 cents per pound) or keep an eye out for a free shredding event, hosted periodically throughout the year by various aldermen. The collected scraps will be sent to a recycler specifically equipped to handle shredded paper.

With Christmas right around the corner, it's worth pointing out that metallic gift wrap is another item that's not recyclable. But you can recycle the cardboard tubes that the paper is rolled around — once you've stopped playing light sabers with them.

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