and here's a site touching on the byproducts of rayon production:

http://www.madehow.com/Volume-1/Rayon.html

and another from Canada:

http://www.unb.ca/che/ioac/projects/2005-2006/rayon.htm

And just for fun, one more (biased just from the title of the website "the greenguide"):

http://thegreenguide.com/reports/product.mhtml?id=32