Ew x 1000.
If you're physically scanning them, why not scan them in color (or greyscale, at least), and then feed them into any of the many commercially available filtering programs? Scanning in black and white like that is just bloody atrocious, and as an engineer, if document control tried to put a print like that in the vault (even a 'cleaned up' version with the background despeckled) I'd laugh in their face.
If you want to forgo the scanner altogether, try using a camera and snapter...
Snapter - "Goodbye, scanner. Hello, digital camera." It will output TIFF's if that's what you need.