I asked this question recently at one UK airport and was confidently told that nowadays they are disposed of/recycled, and the staff can't accept them even if a passenger insists that they would prefer it not to go to waste.
However, I have had a UK security agent ask to keep my Leatherman tool about 5 years ago when I forgot it was with me. I had no problem with that, at the time.
Other option is to post it to your preferred address, assuming you have time to get to the post office - or check it in with your carrier.