Cleaning up UTF-16/CJK characters using PHP?

[justJR]

I have some files on my computer that are in UTF-16, though this seems to be because of errors or corruption of the files rather than intent - they're supposed to be plain english. I uploaded one of these (here). If I leave the encoding in Firefox (Viwe>Character Encoding) at UTF-8 then I get tons of gibberish (see screenshot). If I change the encoding to UTF-16 then it looks much better (see screenshot2), though there are still a bunch of CJK characters present.I'd like to go through all these files and clean them up, and probably save them in utf-8 format (I'll be inserting the contents into a mysql table that uses the utf8_general_ci collation). Does anyone know how I can do this in automated fashion with PHP? I'd like to get rid of all the funky characters the file displays if you try to view it in UTF-8, and also all the CJK characters the display if you view in UTF-16.