U of S | Mailing List Archive | alt-photo-process-l | Re: I have a question

Re: I have a question

From: Judy Seigel <jseigel@panix.com>
Subject: Re: I have a question
Date: Fri, 19 Oct 2007 21:26:54 -0400 (EDT)

> I admit it never occurred to me that it shouldn't be simply
> discarded down the drain, and I wonder if it's OK because it
> DOES break down so quickly?

There are multiple points in discussion of these matters, and
they should be kept separate.

One problem is the regulation. Whether you can dump something
down the drain, and in what quantity and other limitations
(pH, maximum concentration, etc.) varies a lot depending at
the city/town level in the US. I must say quite a few of the
regulations do not make sense (especially in areas with fairly
modern sewer treatment facility) but I do not advocate to
violate them. Dumping formaldehyde, glyoxal, glutaraldehyde,
etc. will most likely violate unless the waste is pre-treated
to break the compounds.

Another issue is the impact to the environment and/or the
load to the treatment facility. For example, draining canola
oil down the drain may not be technically banned in many
areas, I would strongly advise not to do that, but rather to
get a bag filled with old newspaper and dump the oil in it and
throw it away as trash. Fat drained to the sewer system will
require a lot of water to treat it and the load to the
treatment facility is very high. Same principle applies to
some of darkroom chemicals.

Another issue is safety to the operator. Whenever possible I
prefer not to keep waste chemical collection vessel in my
darkroom because it would take many months to fill it up (due
to my very small volume of hazardous chemical use), and
accidental leakage, spill, etc. would be a bigger hazard to
myself. I'd rather spend same effort to use safer alternative
compounds. When small amount of waste is generated, whenever
possible, I would rather treat/neutralize/oxidize the waste to
inert forms before I accumulate them.

> On the other hand, with chemicals I know are bad, I get them
> concentrated (as for instance using a "first tray" for gum
> development until it's practically as thick as molasses,
> then putting it in the back yard with a screen over it until
> it dries, & disposing of it as solid waste),

I don't think it's a good idea to discard dichromate as solid

> tho on the 3rd or maybe it's 4th hand, someone (Mike Ware?)
> said dichromate that's been oxidized and washed (or like
> that) is a tri, not a di, and not bad.  (I may have the
> terms wrong, but I do recall the principle .)

Perhaps you mean that dichromate (hexavalent form), once
reduced to trivalent form, becomes less harmful to the
environment. Like I said previously, one easy way to do this
is to mix dichromate with gum or whatever, and let it get
fully reacted. After this, sulfite can be added to make sure
the conversion is complete.  However, regulation of chromium
in sewer water is a different matter and you should contact
your local government body.

For most small scale users, the best way to dispose these
chemicals is to accumulate them individually (whether with or
without pre-treatment), label each vessel clearly, and bring
them to local household hazardous waste collection.

For most standard b&w silver gelatin processing, waste
chemicals other than used fixer, ferricyanide bleach and
selenium toner can go down the drain to the sewer system (not
septic tank), in small quantity, although they still contain
undesirable compounds.

Ferricyanide is the worst chemical used in conventional b&w
processing. Alternative compounds are available but no one
(but me) seems to advocate phasing out ferricyanide. I don't
know why.

Ryuji Suzuki