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Disposal of chemicals?

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As our Christmas present to each other, my family and I are making our bathroom into a darkroom as we are all photography enthusiasts.

We've read up about it and have found equipment that we want etc. but our only worry is disposal of chemicals. I've heard it's unsafe and

bad for the environment to simply pour chemicals down the drain, but what should we do with them?

Thanks for your help

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Developer and stop, down the public sewer is safe and responsible. For fixer, do silver recovery. Simple way is to pour it in a soda bottle with a ball of steel wool. The silver will combine with the steel wool, you can decant and dispose of the liquid a week later. Or, bring spent fixer to any photo lab, they should gladly take it, since there's lots of silver in it, which they sell for a profit.


Oh, Selenium toner is really nasty stuff. That's real haz-mat.

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There's no good reason to be disposing of lots of selenium toner. If you follow a workflow that keeps

selenium toner in good shape, you may never dispose of your working solution, just replenish the toner

that gets carried off in the prints.


This: http://www.heylloyd.com/technicl/acid_free.htm article, lays out a convincing work process that keeps

selenium toner in good shape pretty much forever. It is a longish article, but very worth the time.



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Color is B+W with 2 added things: a CD to activate the color couplers and a "bleach" to convert silver back to halide when it's done. The bleach these days is essentially plant food, called Ferric EDTA.


You can pour everything down the drain. Of course if you could sell the fix for its silver content, you could try that. Regulations are for businesses which will be pouring large quantities.

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Caustic stuff won't hurt the plumbing, photo chems are very dilute compared to drano and other drain cleaners. Color paper blix is mostly acetic acid, ie, strong vinegar. The silver in the used fix is a pollutant, but the amount you are going to generate at home isn't really worth worrying about.


I'd worry much more about the environmental pollution when the radiator hose bursts on your car. That usually goes down a storm drain and right into a river, bypassing the sewage treatment plant. Or the prescription drugs that go down the drain, consumed or not.

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Irrespective of the real risk there will be laws where you live about what you can and cannot put down the drain.

Check with your local government. Follow what they say.


To minimise your impact, firstly use a developer that contains no hydroquinone - although silver in fixer is

often cited as the most toxic component of B&W darkroom work, hydroquinone is arguably worse. Use Xtol to

develop film and Neutol Plus or a hydroquinone free developer for film and another for paper from Photographers

Formulary or mix it yourself.


Selenium toner should be used up (to complete exhaustion) and mixed with hypo clearing agent prior to discharge.

Selenium is also very toxic.


Used fixer poses a problem, because the silver in it is toxic to the bacteria and accumulates in the system.

There is a lot of info about silver management at the Kodak website:

http://www.kodak.com/US/en/dpq/site/TKX/name/hseSilverManagement but the easiest way to manage it is to

precipitate the silver out of the used fixer with Sodium dithionite


(aka sodium hydrosulfite or sodium hydrosulphite), a white crystalline powder with a weak sulfurous odor. This

substance will precipitate the silver from the solution and separate it from the rest of the components, creating

a benign liquid that can be safely disposed of (on the garden, not down the drain).


You do it like this: put the fixer into a container and add the sodium dithionite, around two tablespoons per

litre. Don't close the canister. Put it in a well-ventilated location at room temperature, perhaps out on a

balcony, as it will produce some sulphur dioxide which smells like rotten eggs. If it is really cold it will not

work - or at least it will take a very long time. The silver will fall out as a black sludge of colloidal silver

and silver sulfide to the bottom and some to the wall of the canister. After a week or so, pour off the excess

liquid and filter the rest through a coffee filter. The black stuff that remains in the filter and the canister

is silver; dry the cake and collect it for further processing or disposal. The liquid can go onto your garden or

sewage or a septic system without any trouble, provided it is legal to do so.


The real risk associated with home use is probably low, but check what is legal and follow the law.



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Silver is also disinfectant. Its what we use to put in kids eyes when they were born to prevent blindness; used to treat cuts and wounds. The sanitary sewer chaps really dont want any stuff to ruin the brewing of the poop; ie that ruins the biological breakdown in the tanks. A giant dump of silver is dumb; place in a tank with steel wool and make money off the silver collected; ie a 1930's technology with no moving parts. A far larger problem is folks flush down the toilet stuff that doesnt break down and causes clogs ; ie plastic bags; RTV sealants; armymen; diapers; socks; rubber balls; zillion safeties; old paint; machine tool coolant; antifreeze; more plastic bags; more plastic rope; more toys; more pill bottles. Today one thing thats really not well controlled but a major problem is old drugs are flushed; and then they make it back into the environment.
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This comes up a dozen times a year. For the average home lab, your silver output is not enough to damage the

local sewage treatment plant. A home septic system might see a decrease in the necessary bacteria and could

slow the waste digestion process. Either use the steel wool as suggested, or let it dry and dispose of the crust with

normal trash.


The comment about color being caustic and will rot your pipes is dead wrong. Another myth. Unless you drink it

and then it will rot 'your' pipes;~) The only color process that is even remotely dangerous is Ilfochrome as one of the

solutions contains a strong acid. However, when mixed with the other two for disposal (manufacturer's

recommendation) it is nuetralized and safe to dispose of.


If you are concerned about the chemicals, get the list of those you would like to use and download from the

manufacturer the MSDS (Material Safety Data Sheet). While you are doing it, download the MSDS for many of the

products used in your home to keep it clean. Compare the LD50's between them and you'll see many of the items

you don't think twice about are more dangerous and deadly than photo chemicals.


Use common sense with these chemicals. Treat them at least as harmful as the ammonia under your kitchen sink

and you'll not do any harm.

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James has the most appropriate answer here. I've been developing film for over 30 years. Everything in a home darkroom simply goes down the drain, color or B&W. Most of it is benign and you simply aren't using enough quantities for it to matter. And there arent' enough people left out there doing home darkroom work for the chemical dumped down the drain by every photographer in town to add up to be enough to matter either. The various chemicals coming out of your washing machines, Draino as mentioned above far exceed your couple of gallons a year of photo chemicals. Whatever you do, do NOT ask local authorities about local laws on chemical disposal. This will only put you on their radar screen and give them reason to want to track what you're doing to make sure you're not a commercial operation. You could be opening yourself up to all sorts of headaches. As for silver recovery, it's only worthwhile on a commercial scale. No jeweler is going to buy a grungy piece of steel wool from you and local commercial labs have enough environemental regs to worry about they're not going to want your used fixer.
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