darkroom chemical disposal

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what is the safest way to dispose of used black and white as well as ilfochrome classic chemicals? i've heard both are harmless thus safe to dump down the drain. anyone have a definitive answere? thanks-ty

-- tyson fisher (lowflyingfish@hotmail.com), February 11, 2000


www.kodak.com has a section on dealing with darkroom effluents. I've heard lots of stories - Bruce Barnbaum says if you mix up developer, stop and fix it makes for a good fertilizer.... Here's my current take based on my flawed knowledge at this point in time. My darkroom and knowledge pertain only to B&W.

The really troublesome characters are SPENT fixer and selenium toner.

Fixer is quite innocuous actually (thiosulphate, sulfite and water). Thiosulphate is used in huge amounts for other applications - even if photography disappeared, there would still be huge amounts of this around (part of the reason this chemical is available cheaply for us is because of the economies of scale from the huge requirements for other applications - paper, detergents, pharmaceuticals, waste treatment facilities etc). Sulfite is used in food processing in huge quantities. SPENT fixer is another issue because of the complex argentiothiosulphates - these silver complexes are difficult to break down. The really complex stuff forms as you keep using the fixer to exhaustion and the earlier complexes are less problematic. In other words, do not use your fixer to exhaustion (thereby you achieve two things - 1/ you do not form complex silver compounds which are problematic and 2/ you actually make washing easier since the complex stuff is also supposed to be more difficult to wash out). Finally silver recovery units will help.

Selenium is a heavy metal and needs to be handled responsibly, although I think it has an unnecessary rap as a poison. Elemental selenium is relatively nontoxic and is required as a trace element by the human body. Some compounds of selenium, notably hydrogen selenide, on the other hand are extremely toxic. Obviously in powder form, it is easily inhalable which is one reason not to mix your own. The selenium toner has an evil smell due to the ammonia (it has ammonium thiosulpahte). The bigger problem is the quantities of selenium being dumped - large amounts do damage the environment (one big concern is the amount of selenium in agricultural drainage water in some parts). So, use the selenium toner to exhaustion (which is probably a good idea since it is expensive). Barnbaum suggests letting the water evaporate off the trays. Trace elements of selenium are perhaps less of an issue since they head for either a muncipal water treatment facility or a septic tank where they ultimately form insoluble compounds of selenium, which are the least toxic forms (obviously you don't want them getting into water supplies or killing aquatic life before this). Needless to add, you do not want large amounts of free selenium floating around the environment either.

Hope this helps. DJ

-- N Dhananjay (ndhanu@umich.edu), February 11, 2000.

I called the Department of Environment. They told me to dump the b+w developer and stop bath down the drain. They said dumping fixer is illegal. It is considered hazardous waste. My township has a hazardous waste pick up once a year. I hate doing it, but I dump the dev. and stop bath down the drain. I collect the fixer in big containers for the hazardous waste pickup. Of course, if you take the silver out of the fixer with a silver recovery machine, that too can be dumped down the drain. I know someone who would put all b+w chemistry in jars, and into the trash, so then it sits in a landfill. FYI, the silver from the recovery can then be sold.

-- Raven (mtand13@netreach.net), February 12, 2000.

Read the new March/April 2000 edition of Photo Techniques. It answers the question very well. James

-- Mr.Lumberjack (james_mickelson@hotmail.com), February 13, 2000.

I'm looking foward to reading the article in Photo Techniques. Maybe someone can post a summary of it. In the meantime I'll say this, and maybe eat my words later. I think the whole issue is a very gray area, and it depends on many variables, and there is no good answer.

Are you concerned about your septic, or your groundwater? IMO, the latter is the one to be concerned about.

Are you dumping a liter of Xtol down the drain every month, or 3 liters of pyro every night? Big difference, IMO.

Is your septic new or 50 years old? Some old septics are nothing more than a pipe into the yard. Is your soil permeable or not? Do you know how to properly maintain and service your system? Some people say just "flush it down with LOTS of water" but excess water compromises septic functioning. Some people never clean their tank, which also compromises it. Some people dump magic enzymes in, but a properly maintained septic needs no added enzymes. Some people even sell magic enzymes that "supposedly" break down photo chemicals, but ask them to provide proof and then please post it here (if you can get it, which I doubt).

Some people will tell you its safe to dump whatever you want, and others will tell you not to dump anything. Kodak no longer recommends dumping photo chemicals into septics. I have not seen substantiating data for either of these views. In light of that, I dont dump chemicals other than rinse water into my septic until the questions are answered to my satisfaction. Read and learn everything you can about the chemicals you use, their personal safety and environmental hazards, their biodegradeability, and then make your own decision.

BTW, just to show the lack of consensus,when I called my health department (the local dept that regulates septics) they said NOT to dump photo chemicals. No good reason was given, it just goes to show you that there is no easy answer.


-- Wayne (wsteffen@mr.net), February 14, 2000.

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