Hang on, it is OK under copyright law to scan a book I bought second hand, destroy the hard copy and keep the scan in my online library? That doesn't seem to chime with the copyright notices I have read in books.
First sale doctrine gives the person who sold the book you bought the right to sell it to you. Fair Use permits you to scan your copy, used or new. It's your book, you can destroy it. But you have to delete your digital copy if you sell it or give it away. And you can't distribute your digital copy.