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Some basic beginner questions about chemistry storage and reuse


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There was a 3 in one developer that came out years ago.. I cannot remember the brand name but heard it had good results.Photo chemicals fall under hazardous waste as your computer does and should not be dumped or flushed. They should be brought to your hazardous waste station in your town.
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There was a 3 in one developer that came out years ago.. I cannot remember the brand name but heard it had good results.Photo chemicals fall under hazardous waste as your computer does and should not be dumped or flushed. They should be brought to your hazardous waste station in your town.

 

Well eddy, yes and no. I have seen talk about the company making the official rodinal making environmentally friendly and safe defeloper, fixer, and stop bath. cant find it for sale online though.

 

Disposal for photo chemicals can depend upon the amount. Most municipalities put a limit on how much can be put into standard waste water treatment systems before you need to get permits and such.

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Disposing of spent photo chemicals:

 

Not all that long ago, I was technical manager of 7 giant photofinishing labs (each 20,000 rolls a day) plus hundreds of in-store mini-labs.

 

Photo chemical handling and disposal was a top priority. I had to become an “expert” so I went to school and became a registered environmental assessor. When it comes to dumping spent photo chemicals down the drain, there is myth and there is lore. Mostly the truth is ignored.

 

For the most part, spent photo chemicals are pretty much benign. What I am saying is -- a home photo lab, disposing of spent chemicals down the drain doesn’t contribute more than a thimble full of harm. That’s because the harm is different from what is commonly believed.

 

The real harm is BOD (biological oxygen demand) and COD (chemical oxygen demand). The home darkroom’s entire monthly discharge is miniscule.

 

The waste we put down the drain, human and chemical, is treated by the municipal sewer system mainly by aeration followed by chlorination. The aeration handles the oxygen demand; the chlorination treats biohazards.

 

The sewer treatment plant is supposed to cut the sewerage oxygen demand to zero. If not, the released sewerage continues to take on oxygen from the waters of streams, rivers, lakes and oceans. Aquatic life in these waters must then compete. If they fail to get their needed oxygen, they die.

 

What I am alluding to – the problem of chemicals in the sewer system -- is their added oxygen demand. A small home darkroom will not have much impact. What will impact is large industrial photo labs and businesses like food processing and chemical manufacturing.

 

Since the photo lab discharge is both acids and alkaline, the net balance of comingled chemical discharge is near neutral. Toxics, if any will become chemically inert within minutes of discharge. Silver, the main agent of discussion, converts to silver sulfite which is inert. Some forms of silver are toxic; the photo lab output is not in this category.

 

What then is the real harm? The answer is the fixer! The fixer we use is the same stuff used by tropical fish enthusiasts to rid tap water of chlorine. If we dump barrels full of fixer down the drain, it arrives at the sewer plant and causes the chlorine they must add, to dissipate. Given this scenario, the sewer plant, which must release, will pass bio hazards to the environment.

 

We, the photographic community wish to be good neighbors. We don’t want to be the source of harm. Let me assure you, your home darkroom’s discharge is not the culprit you think it is.

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Silver, the main agent of discussion, converts to silver sulfite which is inert. Some forms of silver are toxic; the photo lab output is not in this category.

 

...silver sulfite sulfide...

 

And to add a bit to this... the immediate form of silver in photoprocessing is as silver thiosulfate. According to data first published by the US EPA somewhere around 40 years ago silver thiosulfate is on the order of 10,000 to 30,000 times LESS TOXIC to aquatic organisms, etc., than silver nitrate is. (No one doing photoprocessing handles silver nitrate.)

 

But as Alan suggests, more recent studies (perhaps 20+ years ago) have confirmed that any photographic silver getting into a sewage stream very quickly is converted to silver sulfide, which for all practical purposes is insoluble. This conversion happens even in the air as anyone who uses sterling silver eating utensils or wears silver jewelry knows; it "tarnishes."

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Thank you Alan, very valuable info.

 

I wonder if there is any additive to neutralize that chlorine dissipation action of the fixer... I'm thinking on personal actions at very small villages that could have weaker sewer plants.

Edited by jose_angel
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@ jose_angel No need to worry about the amount of fixer from a home darkroom. Yes it will slightly increase the amount of choline the sewer plant will need to use. They collineate by bubbling chlorine gas into the waters of the sewer treatment plant or a small plant will use chlorine tablets like a home swimming pool. In both cases they must achieve a Federal standard choline level in the released sewage. They cannot hold back this stuff as all plants have limited storage. If your fixer has any effect, it will be they need to add an extra tablet etc. As to the silver -- This depends on how they test their sludge. If they use nitric acid reagent, any silver sulfide in the sludge will test positive. Silver sulfide is inert but this test will give a false positive. If the stuff tests positive reducing its value as a fertilizer. but the silver content from a photo lab is still inert.
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Thank you Alan, very valuable info.

 

I wonder if there is any additive to neutralize that chlorine dissipation action of the fixer... I'm thinking on personal actions at very small villages that could have weaker sewer plants.

 

You could put in your own chlorine bleach, which has the same effect except on your end.

 

There are some that suggest mixing developer and fixer before going down the drain.

This allows some cross neutralization, though I am not sure about that one.

-- glen

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How 'bout septic systems? I never had a problem, but only did darkroom work every two weeks or so. My guess is the dilution is so high when you consider the rest of the water usage, it doesn't matter much.

Once upon a time, Kodak Rochester had an environmental department. At the height of world concern over the effluent from giant photofinishing and motion picture processors, this was manned by some of the brightest minds. Most of my training came from their publications and seminars. The subject of home septic tanks came up many times. Privately they were conversed, no harm, no fowl. Publicly Kodak errs on the side of caution. Septic systems drain to streams and rivers thus the photo lab effluent should be hauled away via a licensed agency.

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Thank you Alan.

if the fixer is the issue, what about the citric acid stuff

Citric acid is used for the stop bath, a chemical that is widely used by the food industry (eg duct cleaning) so I don't think it is a problem at low volumes. The one I use can be consumable (preserves, etc.), it is food grade.

---

About septic systems; It could be a real problem, depending on the location and surroundings. The location of these septic systems could be of concern if there are springs or natural water reservoirs relatively nearby that could become contaminated.

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Yep, I spent quite a lot of hours in that book, many years back. As well as the myriad of studies published in the SPSE (later IS&T) journals; by researchers like Austin Cooley and Rami Mina of Kodak, followed up with actual equipment designed and built by CPAC, etc., based on their research.

 

I oversaw the purchase, install, and operation of a CPAC developer regeneration system back when EP 2/3 was the standard paper process. While my boss did similar with an ion-exchange system to recover silver from wash water (he knew I wasn't a fan of that system, but I, or at least my department, had to oversee the operation). Rohm and Haas IRA 400 ion-exchange resin in the developer system, and IRA 68 for the wash water, as I recall. Running 50 gallons per minute through the wash water system all day long when our paper processors were near capacity. The wash water columns were stripped with a thiosulfate solution, then run through an electrolytic silver recovery unit.

 

Back in the good ole days...

 

Here's a little blurb out of the "bible" from a couple years back. Fixer and the Environment

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Could the darkroom chemicals destroy the bacteria in septic tanks or cesspools that dissolve the sewage waste?

 

I'm really doubtful, but don't know for sure. All of the industry research was for "proper" handling of the wastes, and meeting regulatory standards. But I don't recall ever hearing about such a problem, for what that's worth.

 

Still, I would never recommend letting any measurable silver get into your septic tank, mainly because of the regulatory issues. In the US the law known as RCRA sets 5 mg/L silver, as I recall, as the point for determining if something is a "hazardous waste" or not (don't go by my word, though; verify by the actual law). Imagine if you wanted to sell some property, and a regulatory body decides that an environmental audit is called for... it's just not a position you want to let yourself get into. I gotta emphasize, though, no one should make decisions based on the opinions I'm giving here. They gotta research all the appropriate laws themselves.

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