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  1. #1
    NedL's Avatar
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    Used Sodium Thiosulfate disposal

    I save all my used fixer to go to my county hazardous waste disposal site. Is it safe to add used plain hypo fixer with used rapid fixer? Or do I need to keep them in separate containers?

    In Alan Greene's book, discussing development of calotype paper negatives, he makes a point of saying to keep used sodium thiosulfate fixer exhaust separate from the other silver nitrate exhausts which consist of used gallic acid developer and the first rinse after development. He says if they are mixed it can produce sulfur dioxide, but not what causes that reaction. I know ammonium sulfate rapid fixer is acidic, but not if that could be what causes sulfur dioxide to be formed.

    Advice appreciated!

  2. #2
    Worker 11811's Avatar
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    Recover the silver before you dump or otherwise dispose. Depending on how much you use your fixer and what kind of film you use, you could get as much as 2 or 3 ounces of silver out of a five gallon bucket full of spent fixer. At current prices, that means, you'd be dumping $80 down the drain.
    Randy S.

    In girum imus nocte et consumimur igni.

    -----

    http://www.flickr.com/photos/randystankey/

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    Sodium thiosulfate is used in water purification plants for town water. Don't worry about it. The silver in it will become silver sulfide (no shortage of available sulfur compounds in the sewer!) which is stable and won't bother any living thing (so stable that sulfided prints last longest).

    Recover the silver if it's convenient, of course.

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    It's probably a good idea to obey, to the letter, local disposal regulations. Not because they are chemically or biologically correct but - more practically - to avoid fines, imprisonment and having your darkroom confiscated.

    If you can reclaim the silver then that is a very good plan. In any case the majority of the container consists of water, and this evaporates very nicely leaving minimal residue. Obviously, arrange things so that animals cannot drink the stuff (or drown in it) while you are evaporating the water.

  5. #5
    Roger Cole's Avatar
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    Quote Originally Posted by john_s View Post
    Sodium thiosulfate is used in water purification plants for town water. Don't worry about it. The silver in it will become silver sulfide (no shortage of available sulfur compounds in the sewer!) which is stable and won't bother any living thing (so stable that sulfided prints last longest).

    Recover the silver if it's convenient, of course.
    I got in quite a row saying pretty much this same thing on here before. You are, of course, absolutely right.

  6. #6

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    Quote Originally Posted by noacronym View Post
    For pete's sake. Photography is nearly dead. Not EVERYBODY is pouring 5 gallons a day down the sink Your little gallon is a drop in the ocean. A molecule in the universe I can't believe the micro-managed political correctness. Just get rid of it. I really do think some kind of PC insanity has taken root in this country. Like kudzu. Quit worrying about it.
    Quote Originally Posted by noacronym View Post
    Pardon me for that, my photographic friend. I see you're from California. When I think of California, it's not beautiful redwoods and lush valleys that come to mind. Immediately I think of several women riding brooms. And that leads me to wonder who keeps voting them back in. Believe me friend, your little gallon of used fixer is NOT a dirty bomb. It's not anthrax, and it won't heat up the earth and kill everthing. Enjoy your photography. Don't let those screwballs fill you with ideas you're destroying god's creation.

    i'm always amazed that people condone dumping stuff down the drain ...
    it reminds me of someone who suggested it was just fine to dump cyanide down the drain
    because there aren't many people doing it, or the guy down the road who was dumping fluorescent green
    machine shop solvent down the storm drain .... because he paid taxes and could do whatever he wanted ...

  7. #7
    Bob Carnie's Avatar
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    Quote Originally Posted by jnanian View Post
    i'm always amazed that people condone dumping stuff down the drain ...
    it reminds me of someone who suggested it was just fine to dump cyanide down the drain
    because there aren't many people doing it, or the guy down the road who was dumping fluorescent green
    machine shop solvent down the storm drain .... because he paid taxes and could do whatever he wanted ...

  8. #8
    Bob Carnie's Avatar
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    All photo Labs, private darkrooms, schools in the GTA of Toronto that dump fixer down the drain can and will be shut down.
    Therefore each one has a silver recovery plan for the fix. If not they can come to my lab and dump the used fix into the unit.

    RA4 bleach fix, rapid fix, regular fix does not matter .
    Not to mention backflow regulators at the point of entry of each building .

  9. #9
    Roger Cole's Avatar
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    Used Sodium Thiosulfate disposal

    Quote Originally Posted by jnanian View Post
    i'm always amazed that people condone dumping stuff down the drain ...
    it reminds me of someone who suggested it was just fine to dump cyanide down the drain
    because there aren't many people doing it, or the guy down the road who was dumping fluorescent green
    machine shop solvent down the storm drain .... because he paid taxes and could do whatever he wanted ...
    Fixer is not cyanide nor machine shop solvent. Of course comply with local laws. But you probably dump worse things than fixer down your drain all the time, previously stored right under the sink.

  10. #10

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    Quote Originally Posted by jnanian View Post
    i'm always amazed that people condone dumping stuff down the drain ...
    ...
    While I don't condone dumping just anything down the drain, dumping small amounts of used fixer may sometimes be the best solution.

    Ideally, of course, performing silver recovery before dumping fixing into the municipal sewer is a good idea. For some of us, that is no longer practical.

    I used to take my used fixer to a local photo finisher for silver recovery. They were happy to get it (they made money from the recovered silver) and took it off my hands for free. They have longs since gone out of business. There are no longer any photo finishers around to take my fixer.

    Another alternative is to take the fixer to the local hazmat facility. I tried that a couple of times. The goons working at the facility had no idea what I was trying to give them, seemed to be unfamiliar with silver recovery and handled the used fixer like it was toxic waste from Fukushima. The used fix just got labeled "photo chemicals" and I'm reasonably sure that it never got to any kind of silver recovery unit. So much for the hazmat people.

    That leaves do-it-yourself silver recovery, which is a great idea and something I will initiate as soon as I have my own, and not a rental, darkroom. In my present situation, I will simply dump the five to ten gallons a year of used fixer down the drain. A less-than-ideal but still fairly responsible solution.

    FWIW, Kodak in the tech pub J-300 states:

    "Although the form of silver (silver thiosulfate) found in photographic processing effluent is not harmful and is removed during secondary treatment at the POTW, it is a good practice to recover silver before discharging the effluent."

    I interpret this as "recover if you can, but go ahead and dump if you must." Especially for low-volume users, a few gallons a year of used fixer down the drain is not an environmental concern.

    Best,

    Doremus

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