How does WD dispose of data on a bad drive?

I have a 1.5 TB WD Caviar Black drive that has over 1300 reallocated sectors and fails read tests.  I am currently awaiting a replacement from WD.  My question is this:  How does WD dispose of the data on the failed drive when they receive it?

Hi there, I think you’ll find this link a bit helpful.

Other than that, I think you’ll need to ask WD directly just how do they do it… I don’t think that’s public info.,…

Thank you for the link.  That answered my question.  However, I think I’ll also run DBAN before I ship it back (assuming DBAN can function with the drive failing as it is.)