Larry wrote:
Larry wrote in news:Xns9843578EFEF11noonehomecom@
208.49.80.253:


Uhmmm...if you use the carbon before the still, they are not there to
carryover are they? With the added benefit of chlorine removal, which
is plus for life of stainless steel (assuming you're not trying to
distill seawater, that is).


Argonne National Laboratory has solved the RO filter problem! They distill
the RO output....(c;

http://www.newton.dep.anl.gov/askasc.../chem00223.htm

"The industrial R.O. system I monitored at my last position
produced water that conformed to USP specifications,

Which means exactly nothing. USP specs for what? Potable water? Purified
Water? WFI? Sterile WFI? Water for Irrigation? Each has specific
compendial requirements.

but we also distilled
the R.O. water for lab work. Some analyses require freshly distilled water
(hasn't drawn carbon dioxide from the air)."

Actually, I've never seen a still in lab use in pharmaceuticals.
Typically they use UF systems like a Millipore MilliQ.

None of which however, has anything to do with the point. Carbon
upstream of distillation does *everything* it could do downstream, as
far as removal goes, and does so without microbial concerns.

As for "solving" the RO filter problem, that's *OLD* hat. Been working
with manufacturing various compendial waters, including WFI (water for
injection) for 25 years and yes, distillation is the last step (although
double pass RO may be used, from a compendial perspective, it isn't in
practice).

Carbon beds are always in the front end, never the back end. Then
RO/IEx/EDI, or a combination thereof, in the middle.

Keith Hughes