According to Kodak and most other chemistry suppliers, small quantities (up
to ten liters or so) of common developers, and fixers, normally diluted
with wash water, actually can aid septic tank operation. Some of the
"alternative printing" chemicals are not good for the digestion that is
required by the septic tank process. Kodak has literature on this; you
might drop over to their Web site <http://www.kodak.com> and get the true
word!
Now, if you are planning to run a commercial operation, with thousands of
gallons/liters of effluent, that's another matter. I think they have
information on that also.
Sil Horwitz, FPSA
Technical Editor, PSA Journal
silh@iag.net
Visit http://www.psa-photo.org/