at the hazmat locations they usually don't want anything mixed
they want everything labeled and separate ..
im glad i don' t live in CO the last thing i want in my rain is
nasty photochemistry ...
where i live things are quite strict, they don't want anything down the drain
photo chems are not the nicest things for the water, i don't blame the people
for not wanting to have it mixed in ...
if it was me, i'd just contact a waste hauler and have them deal with the stuff that isn't fixer.
i'd save my spent fixer and wash water
put the silver through a silver magnet to get the silver down to about 50, then with the wash water
into a trickle tank to get it below 5 and then into the 15 or 50 gallon drum for the waste hauler.
then when the magnet is full of silver i send it in to be refined, and i get a check for 800-900$
and it pays for everything, the magnet ( and its replacement cathode ) the trickle tank, and the waste hauler ..
that way there is a paper trail if the powers that be get nosey ...
and yes, that is exactly what i currently do, so if they want to get nosey i have records for the last 13 years that
say i did what was expected ..
good luck with your situation, i hope it gets easy for you, cause it sounds like a PITA ..
ps thanks matt !
I post this one a few times a year but it is still relevant.
I've had the luck to enjoy a career in scientific research and analytical chemistry before taking up photography full time. One of my challenges was teaching chemists at the local water supply and sewerage department about photographic chemicals in the effluent they had to treat. The "no fixer down the drain" anxiety comes up about a hundred times a year and has been doing so for at least half a century.
The following does not apply to industrial scale photo materials manufacturing or a major processing lab, only households connected to a sewer line or a proper septic system:
Developers are mild reducing agents that oxidise rapidly to inert components. The BOD (Biological Oxygen Demand) challenge offered by a home darkroom is much (much!) smaller than the BOD from a dishwasher, in-sink garbage disposal unit, or a toilet.
Stop bath is a very mild acid that has no measurable effects on highly buffered systems like septic tanks or sewerage treatment plants.
In moderate quantities (ounces, not tons) silver tetrathionate and similar compounds which characterise used fixer don't harm sewerage treatment systems or septic systems. The silver very quickly gets converted to silver sulphide in the presence of the free sulphide ion (smells like rotten eggs!). Silver sulphide is geologically stable and biologically inert and has one of the lowest solubility products known in chemistry. The stability and inertness of silver sulphide is the key to the remarkable archival properties of sepia toned photographs.
Do your own calculations. Just estimate your yearly use of silver from your photographic materials consumption, allow 1 milligram per square inch, and divide this by your yearly water consumption from the water meter. I bet it's in the parts per billion range where no conceivable biological effect can be credibly imagined. If you are discharging into a sewer system your used fixer contribution will be diluted by thousands of household that don't do photographic processing; that's just about everybody. Down at the treatment plant your speck of silver won't be detectable by any known analytical technique. People washing silverware in their dishwashers will send down more silver than you will ever do.
In my professional career I have inspected home septic systems that have been "ruined" by people doing photographic processing. In every case it has been the fault of extravagant archival washing at the end of the processing sequence. Sending maybe two or three hundred extra litres of water a day into a system for days on end dilutes the activated sludge and slows the biological reactions that process and neutralise the usual septic stream. The extra water can also overwhelm the soakage pit or trench that lies at the end of the septic system and deliver a squelchy smelly mess.
The world being what it is many local effluent standards are written by lawyers and/or accountants who don't know a dot of chemistry but know about culpability and lawsuits. Even Kodak publication J-300 which is the de facto last word on "fixer down the drain" is more about avoiding potential disputes and less about the niceties of chemistry.
Here's a typical calculation: A home darkroom processes, say, 2000 sheets of 8x10 black and white photographic paper a year. If half the silver goes down the drain that's 3 ounces. If, instead of disposal, much of that is recovered and sold the net return after refining costs could be up to $30 per annum on today's silver market. A lot of people would say its not worth the trouble. Opinions differ.
If you choose check with local authorities, ask their permission for what you intend to do, and they say no, I guess you have to comply.
In this whole discussion one should not forget that silver is still a sought for raw material. Any mole of silver sent down the drain has to be dug out of the earth in mines. Sometimes under bad working conditions.
Originally Posted by Maris
your calculation is a little off ..
there is about 1/4 oz of silver in a gallon of well spent fixer.
i am not sure how much film or paper that is in a year, or how often you
use a gallon of fixer, but its about 1/4 oz/gallon ....
In more detail here's a broad calculation for a home darkroom using 2000 sheets of 8x10 gelatin-silver photographic paper per year:
Silver content of photographic paper is notionally 1 milligram per square inch so 2000 sheets or 160,000 square inches of paper carry 160 grammes of silver.
160 grammes is about 6 ounces. If half the silver stays in the paper to make the pictures the other half goes out in the fixer. That's about 3 ounces.
World silver prices vary but at $20 an ounce the discarded silver is potentially worth $60.
Allowing for the expenses in recovering the silver, shipping the concentrate, and refining it back to metal, the home darkroom operator could potentially score every year a $30 ingot about the size of a large coin. Turning this ingot into cash could fund the purchase of maybe 30 sheets of 8x10 photographic paper.
Worth it? YMMV.
Originally Posted by Maris
You aren't including the environmental cost of pulling that silver out of the ground again.
Maris -- What are your recommendations for disposal of depleted selenium toner working solution.
selenium toner is bad stuff.
dispose of it the "right way" even though someone
on the other side of the world may suggest its harmless.
stranger things have happened here on apug with scientists nonetheless
not saying maris is like this person, he has a respect for photography
annd its chems...
but several years back a scientist-lady said selenium was harmless, and nontoxic ( the bottle says differently!) because it is in seawater/ soil/ multivitamins.
while taking advice from experts on a webforum can be ok sometimes i would find out what local authorities suggest for disposal of photochemicals ( dev/ fix) and more exotics like toners ..
maris the " industry standard" is a gallon of well spent fix has a quarter ounce of silver in it .. you can argue all you want but that is the standard that wastehaulers go by ...
and as others have suggested the destruction caused by extracting silver from the ground is pretty hellish
I'm not Maris, but I'll risk hijacking the thread and take this on since it is one of my pet topics.
Originally Posted by DAK
I never dispose of selenium toner. I replenish it, filter it and reuse it -- indefinitely. I have two gallon jugs of selenium toner of different strengths that have been going for about 10 years (maybe longer). No problems with toning activity or print longevity. I routinely do residual hypo and residual silver tests on my prints and they all pass with flying colors.
My technique is as follows: When toning times become too long, I simply add a small amount of the selenium toner stock to the working solution to increase its activity. You'll have to determine what amounts work for you, but start with, say, 30ml/liter. If that doesn't step up the activity enough, add more; if it ends up being to active, simply dilute your toner and use less next time.
Toner used in this way precipitates out a black residue that is primarily silver/selenium. This is harmless to the prints and easily filtered out using coffee filters or the like.
There are those who use selenium toner "mechanically," e.g., at a particular dilution (say 1+19) for a particular time (say 2 minutes). This is done for "archival processing" reasons or "to increase D-max." Toning like this without monitoring the visual effect of the toner is ineffective. Toner activity begin to change after the first print is toned and decreases steadily with each print toned. Not extending the time simply results in successive prints receiving less toning. Additionally, if there is no visible effect either a change in image tone or a deepening of the lower print values, you are getting neither an "archival" effect nor an increase in D-max. Tone using your eyes, a good light source that approximates the display lighting you prefer and an untoned, wet print next to the toning tray as a reference. FWIW, only fully-toned prints are "archivally" protected; partial toning (which is what we most often do) only partially protects the prints. Careful fixing and washing maybe plus a stabilizer (Sistan or one of its successors) is the best way to ensure print permanence if you don't want to tone to completion.
If you must dispose of selenium toner, use it to exhaustion and then toss a few scrap prints into the solution and let them sit overnight to scavenge as much selenium from the solution as possible before discarding.
--- Down from the soapbox ---
And back on topic: Do a quick search for Kodak Technical Publication J-300 on disposing of chemistry. It may not take local regulations into consideration, but contains sound advice.
For the home darkroom and low-volume darkrooms, developer and stop-bath disposal should be of no concern. Simply dilute and dump into the sewer or septic system (I used a darkroom with a septic system for years and had zero problems doing this). Fixer with its silver content is the main concern for me. I used to take my spent fixer to a local photo lab, which gladly took it for silver recovery. They disappeared, so I began taking my fixer to the hazmat collection site. I soon learned that they didn't send the fixer for silver recovery; they simply mixed it with lots of other stuff and sent it for incineration. I don't think it is particularly eco-friendly to use a lot of energy incinerating relatively benign chemistry instead of recycling, so I stopped doing that. (Besides, the hazmat personnel I dealt with were badly trained, had no idea of photochemistry, silver recovery or the like and treated everything, including my five-gallon jug of spent fixer as if it were a mixture of sarin gas and nuclear waste... really overkill and way ineffective for my tastes).
Lately, I've been dumping small amounts of spent fixer down the drain into the municipal sewer, as Maris and Kodak suggest. When my volume increases after my darkroom remodel, I'll likely get a small silver recovery unit from jnanian here and simply dump the fixer down the drain after silver recovery.
over the years kodak has done a great job contradicting itself :)
(with septic) kodak recommends not dumping any photochemistry down the drain
it is from 2005 --- j-300 is from 1999 ..
of course it depends where you live that should determine what tack you should take ..
and as always ... YMMV