Every year in the United States, there are millions of books being purged from library shelves to make room for new ones. Libraries do try to find a home for them by holding a book sale and unsold books are recycled and turned into mulch. From my perspective as a gardener, recycling isn't such a bad thing.
I found this out while attending a Book Sale in Tampa, Florida in 2000. At one of these book sales, I asked the Chairman what they do to the unsold books. She offered for us to haul as many books as we can use after I told her that we just sponsored our first Children's Library in the Philippines. That was 2004. Since then, we have found 28 homes (libraries) in the Philippines for over 50,000+ unwanted books. Some books were brand new that no one borrowed, others were gently used, and some needed repairs.