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  1. #11
    Bill Hahn's Avatar
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    Quote Originally Posted by laz127
    In the late '60s early '70s the Cayoga River near Clevland Ohio would occassionally catch fire! Can you imagine that call to the fire department. "help our river is on fire!"

    Have you heard the Randy Newman song "Burn On, Big River"?

    ("Cause the Cuyahoga River goes smokin' throught my dreams!")
    "I bought a new camera. It's so advanced you don't even need it." - Steven Wright

  2. #12

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    i only use developer fix and fix remover and they all go in a 30 gallon drum when i am done with them. about 1 time a year +/- a waste hauler comes by and takes it away. he gives me a receipt for my "cold storage" file cabinet and in about a month's time a get a check for $$ which covers the for the cost of the disposal and will buy me a couple bottles of wine. even if i happened to be a "hobbiest" i would feel kind of guilty dumping the stuff in the drain seeing that we have a septic system and neighborhood kids play in our front lawn ( leech field ). even though most of the chemistry breaks down, and silver reclaimation companies like itronics make fertalizer out of spent fixer, i would feel pretty bad if one of the local kids got sick because of my callousness.

  3. #13

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    Quote Originally Posted by laz127
    And you should be proud! Europe is far far ahead of the US in environmental awareness. Much of europe has well considered and scientificly rigorous regulation. Part of the explaination of course is that the countries of the European union know from hard experience how their neighbors environmental actions or inactions impact them; the waste one county dumps in the Rhine on Monday becomes another country's problem on Tuesday.

    Americans worship their freedoms, even those that will eventually kill them.

    -Bob
    Swedish wastewater restrictions are completely out of proportion to the danger posed by home darkrooms. Most municipalities forbid any photographic chemicals in the drains, which is ridiculous, since standard B&W developer, stop bath and fixer is harmless.

    That includes spent fixer - as Donald notes, the silver precipitates as silver sulfide before it even reaches the treatment plant.

  4. #14

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    Quote Originally Posted by laz127
    5. Trivalent chromium may be the ultimate carcinogen responsible for the effect of hexavalent chromium since it is able to bind DNA directly. However, it is unclear whether the reduction of hexavalent to trivalent chromium and the subsequent oxidative damage, or the direct binding of trivalent chromium to DNA, or both is responsible.
    That's interesting. I know that hexavalent is a much greater concern than the tri, at least from the EPA side of things... But the USEPA has established the Federal MCL for Total Chromium at 100 parts per billion - hexavalent or otherwise. (Actually, I don't think they have limits (yet) for hexavalent Cr in drinking water.)

  5. #15

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    Emil,

    Potassium dichromate is a Chr6+ compound. Hexavalent Chromium is highly dangerous for human/animal health and environment. It's known to be a human cancirogen, may cause burns on your skin, severe damage to your eyes, and there are also people allergic to it (a test at the hospital can determine if you're allergic to chromium). One should always use gloves, glasses and mask while using this chemical. Anything which came in contact with it is to be considered contaminated. Be careful to not let some of this chemical go on your clothes.

    Here are somoe MSDS about potassium dichromate:
    http://www.atmos.umd.edu/~russ/MSDS/...dichromate.htm
    http://ptcl.chem.ox.ac.uk/MSDS/PO/po...ichromate.html

    Disposing of exhaust dichromate from developing baths can be a problem and a legal issue too if your local regulations are very strict. Since you teach in a photography school, I believe you can dump toxic liquids there. People who don't have this possibility should ask if some lab nearby would be so kind to get rid of it.

    Anyway, you can also reduce chromium from hexavalent to its trivalent form Chr3+. This is always toxic, but far less than Chr6+. To reduce the chromium you can use potassium metabisulphite (about 5% concentration or more). Hexavalent Chromium (Chr6+) is yellow-orange colored (turns very yellow when it is put into an alkaline environment). The Trivalent Chromium is light green/blue color (very nice to see). Since this difference in color, you can always tell when the potassium dichromate contains Chr6+ or Chr3+.

    I've recently bought 1kg of Potassium Dichromate to start experimenting with gum bichromates and other things... It's still in its safety bottle.

    If you have problems to buy this chemical in Denmark perhaps I could bring it from here...

  6. #16
    OldBikerPete's Avatar
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    I suppose it depends on your rate of usage. My rate is about 10 8x10 color prints/month. I put all my wast chemicals into a large PVC tray and let it evaporate. At infrequent intervals I collect the solid residue and take it to our local council as solid chemical waste.

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