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Fixer and the Environment


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So using steel wool without soap (oil?) and putting it in a plastic? metal? bucket and then pouring the fixer on top of the wool and then letting it sit covered? for some number of hours or days? will allow me to pour the liquid out down the drain. Then I have steel wool with silver in it. Can this be thrown away? Or do I need to dispose of that in any special way? Is there a ratio of how much wool I should use vs. the amount of spent fixer? Typically I used the fixer a few times before pouring into the bottle.

 

When I was young, I poured it all down the drain and didn't even know it was harmful. I'm just trying to do the right thing now. Thanks for responding. Maybe you helpful folks can fill in some details for me to try.

 

Kmac yes I saw that thread and that is one of the threads that gave me the steel wool in a bucket idea, but there is never a lot of detail. for me a few jugs of this stuff is decades worth for me and I shoot less film today. I expect it's a one time shot. I may have more but I won't accumulate much more or as fast.

 

And pouring it down the pipes once I remove the steel wool after the procedure won't cause any risk to the pipes? Or do I need to do it in the street in the drain?

 

Thanks again for your posts.

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Two thoughts - you could air evaporate the liquid - the residue from your current chemistry plus another half a lifetime of hobby use would not fill a two pound coffee can.

Second, before I lived in the country, our suburban town had a facility that accepted hazardous waste, virtually anything that shouldn't go in the garbage. Can't recall if there was a small fee, but you did have to show I.D. to prove you were a resident. When clearing the house to move I brought them worse things than photo chemicals with no problem.

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Fixer formulas, sodium thiosulfate and ammonium thiosulfate contain sulfur. Spent fixers contain silver in solution. A high volume photofinisher may have a fixer silver loading exceeding 10 grams per liter. Silver is what the municipalities don’t want. This is because, in the course of their treatment, silver compounds fall out of solution and comingle with the sludge. Sewer operators sell sludge; it is used to make fertilizers and as land fill. High silver content reduces the value of the sludge. (1 gram = about 1 raisin).

 

However, silver is not the real problem. This is true because the fixer, loaded with sulfur, reacts with silver forming an inert compound, silver sulfide (harmless). The real menace: A few drops of fixer causes chlorine to effervesce and come out of solution (this is the stuff of aquarium de-chlorinator. The treatment plant must chlorinate to kill bacteria (federal law). The chlorine level must be high like that of a swimming pool. Fixer from a commercial lab will elevate the cost of chlorination. Home-based darkroom activity has minuscule effect, likely below detectable levels.

 

Why the fuss? Municipalities test for silver. The test uses nitric acid to liberate silver sulfide. Thus the test is positive. However, nature can’t liberate this compound, so the sludge is benign. This does not change the fact that a positive test reduces the selling price of the sludge.

 

Electronic silver recovery at the photo lab, if operated with due diligence, reduces the silver content of the fixer from 10 grams per liter to 1 gram per liter. The plated-out silver is 95 to 98 percent pure. If the lab attempts to continue extracting silver, the lowest they can get is perhaps ½ gram per liter, and this will be degraded because it will be silver sulfide, which has greatly reduced value, it is harder to refine. At about ½ gram per liter, electrolyte activity ceases. To obtain 5 mg (federal requirement) the lab must polish the effluent with iron wool or chemical precipitation.

 

Why would a photo lab use electrolytic method? Fixer becomes exhausted as the silver level climbs. Using the electrolytic method to reduce silver in the fixer to 1 gram per liter is desirable as this solution can be reintroduced into the processing machine. Fixer treated with iron wool is contaminated and thus discarded.

 

Spent developer reverts to coal tar and the alkali solution is neutralized by the chlorine which is an acid. Fact is, home darkrooms contribute a thimble full of effluent and this no impact. It is the commercial photo labs that municipalities are worried about. Factorial: There is a fact that ordinary households (no photo lob activity) contribute a surprisingly high level of silver to the waste stream. The source is unknown. In many cases, the silver content will be at or above the 5mg federal standard.

 

I was a registered environmental assessor licensed in California for photo effluent.

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The fluid that exits a well operated iron or steal wool recovery system will test 1mg to 1/2 mg silver. 1 mg is the weight of a 1/1000 of a raisin. This will be further diluted by your household sewer water, nobody can detect it, it will do no harm unless you are handling 100 rolls or more a day. The iron wool contains silver that is about 30% pure. It has value and most municipalities will not permit disposal in garbage. You need to sell it to a silver recovery firm or take it to a hazardous collection point. The remainder of the photo effluent is harmless even if you are processing color film. Hazzard is in the eye of the beholder. Many municipalities will say no thank you because they don't know what they are dealing with. You can bottle all this stuff and take it to a hazard's collection site. Me, If I am process under 10 rolls of film a day, don't give this another thought. Photo effluent is low on the toxic scale because acids and bases comingle and net result is neutrality. Edited by alan_marcus|2
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Ok, so use the steel wool in a bucket and pour the spent fixer backlog into the bucket through the steel wool and maybe cover for a few days then I can throw away the liquid. For the future if I don’t do more rhan the occaisonal roll I could just pour it down the drain. Then look for a silver recovery company to get rid of the silverized wool.
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... have maybe 3 gallons of spent fixer in the garage that I reused several times before I poured into these jugs. They've been sitting in my garage for decades...

 

I'm just guessing on this, but after decades in a jug I doubt that any thiosulfate is left (this is the active ingredient in fixer that "holds" the silver). My guess is that you have a sludge in the bottom of your jugs that includes nearly all of the silver as either metallic silver or silver sulfide. If this is the case, then you are not gonna be "recovering" any significant silver with steel wool nor with electrolytic means; in essence the silver is already "recovered" in the sludge. But again, I'm just guessing; the bulk of my experience has been with continuous processes, not chemicals stored for extended periods of time.

 

If there is any question as to whether the liquid is still viable as a fixer you could decant a little off the top and see if it is capable of clearing a small piece of unexposed film leader. If it can't do this then there's not much likelihood that it is still holding any silver in suspension.

Edited by Bill C
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I will assume you are processing 35mm wide film. A 24 exposure roll less sprocket holes has an area of 0.42 sq. ft. A 36 exposure roll has an area of 0.592 sq. ft. 1000 sq. ft. of 400 ISO film contains 1.1 Troy ounces of silver. Thus one roll of 24 exposure contains about 0.0005 T oz. and a 36 exposure contains 0.0007. Suppose you process 100 rolls of 400 ISO 36 exposure. The film stock for 1000 rolls contains 100 X 0.0007 = 0.07 T oz. When the film is processed, about 60% of this silver will be in the fixer, 40% will make up the image on black & white film. If its color film, 100% will be in the fixer.

 

OK, how much is 0.07 T oz. = about 2 grams = about 2 resins. Do you think this amount of silver down the drain will harm?

 

Normally we put steel wool in a plastic container and allow the fixer to trickle in a few drops a minute. About a inch down from the top of the container we cut an exit hole and allow fluid that exits to go down the drain.

 

This is a chemical reaction based on the activity differences between iron and silver. The silver trades places with the iron and remains as a slugged consisting of silver sulfide. The fluid that exits contains iron in solution.

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Reminds me of a high school chemistry experiment. The idea was to put a nail in the solution, which would plate out copper as it dissolved the iron, in the same way as above. For some reason, the cart I had, instead of a nail, had a bag full of tiny iron staples. There is no way to scrape the copper of thousands of staples, so my teacher instead gave me sulfuric acid to dissolve away the rest of the iron. I don't remember now if it came anywhere close to the expected answer, though.

 

Silver metal, and insoluble salts, don't do much down the drain. Some silver compounds are slightly bad, but not all that bad.

 

It is industrial sized labs that the sewage people worry about.

-- glen

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Alan, your figures don't add up. You stated:

"The typical roll of 35mm black & white film contains about 0.008 Troy Ounces of silver."

That's around 0.25 grams.

 

You then go on to say:

"A high volume photofinisher may have a fixer silver loading exceeding 10 grams per liter."

 

And from your previous figure that would be the entire silver content of 40 rolls of fim.

 

- Sorry, but I'd like to see the fixing solution that can be used to fix in excess of 40 films without regeneration.10 normally exposed and developed rolls of medium-speed film per litre would be pushing it!

 

Wait. I see you've now revised the silver content per roll to 0.0007 Troy oz per roll. That makes the capacity of fixer upwards of 450 rolls per litre to get 10 gms of silver in solution. Very doubtful.

Edited by rodeo_joe|1
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In the hay-day of photofinishing I oversaw 7 giant photo labs, each sized to develop and print 20,000 rolls of film a day. Sizing is for holiday loading like Xmas volumes. Anyway, a photofinisher uses electrolytic to reduce the silver loading of the fixer to 1 gram per liter. If set lower, the silver in the electrolytic device sulfurizes. The fixer in the working tanks are replenished. If on silver recovery is utilized, the loading in those tanks can reach 10 grams per liter. Historically, when silver was under $3 per troy ounce and with no government regulation few practiced silver recovery. I have seen the stainless steel tanks with 1/2 to 3/4 inch coats of silver after years of operation. After you process several rolls, dip a shiny penny halve way submerged in the fixer. In minutes, silver will plate, because the top half is not submerged, you will be amazed at the difference top and bottom.
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My number of bottles is what I remember, but they’re smaller. I probably have about a gallon of spent fixer (which I typically use 3-4 times) in bottles which may be over a decade old at this point. I sent an email to my county waste disposal and if they reply, I will post.

 

Obviously, if you’re not mechanically inclined to make some way to trickle the fixer onto that steel wool and just pour it in, it won’t be as effective based on what I’m hearing. I suspect that I may take up the county to dispose of it if that turns out to be possible (just in case and because I’m not really sure I have a smaller problem with a smaller amount of silver sludge). In the meantime, I still find it all fascinating and plan to keep listening.

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I suspect that the county guy can't just pour it down the drain, without knowing exactly what it is.

 

In Seattle, we have household hazardous waste collection sites.

 

Among others, they worry about mercury. They collect fluorescent bulbs, thermometers, and mercury switch thermostats.

I suspect that they would also want mercury containing photographic chemicals. (Also Hg batteries, I have brought some of those.)

 

I also bring them NiCd batteries, as Cd is pretty bad. Other batteries aren't so bad, though I believe that they will take them.

 

There are limits meant to keep things to household size, though.

I suspect that there is another system for industrial hazardous waste.

-- glen

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I just got to say -

Hooray for Alan Marcus! - he's a "value-added contributor"

 

Yep, Alan is a good one for general background insider info on the industry, and to help put things in perspective.

 

I would quarrel a bit about some of the finer details, though. For example, in the US, photofinishers who use the municipal sewers are subject to neither federal nor state standards with regard to silver in their effluent. Rather, these finishers are subject to local municipal regulations. The local municipality has laws regarding exactly what concentrations of certain chemicals are permitted to go to their sewage treatment plant, aka the POTW (publicly owned treatment works).

 

Many of the municipal regulations were established by people who didn't really know what they were doing; they largely copied the details from other towns. Consequently there was a wide range of permissible values for silver concentration. A good number of municipalities would set limits at about two-tenths to three-tenths of a milligram of silver per liter. This is just virtually unachievable for a run-of-the-mill finisher, so they are forced into using a licensed hazardous waste hauler to take their silver-bearing waste to a treatment/disposal specialist. (Thus the invention of the "washless" processing systems, to minimize what has to be hauled.)

 

Now, the person who DOES use a waste hauler IS subject to federal (and possibly state?) regulations, etc., where I THINK that anything over 5 mg silver per liter, where it is possible for the silver to be leached out, is considered to be "hazardous waste." It's kind of a nutty situation, where the POTWs, who are going to treat the effluent, are sometimes using a max allowable silver concentration, for the photofinisher, that is roughly 20 times lower than the federal haz waste number. On top of that, studies have shown that the photographic silver is relatively benign, being somewhere between 10 and 30 thousand times less toxic than ionic silver (such as you would get by dissolving silver nitrate, for example). Well, I guess I did enough grousing for the moment. (I already gave my advice earlier.)

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County email hasn't gotten back to me yet. I did find a pretty extensive booklet on how to handle a wide variety of stuff related to pouring down the drain. Very informative but they didn't mention photographic chemicals. I suspect it's because compared to what things were like in the 70s or 80s, there is very little black and white photo processing going on these days. No drug store I know of does it (they print from digital cards now) and most photo stores are gone. Only professional places and a few quirky places tend to do it, or places where you send film away to. Moving On might be right in the contention that they probably don't care that much because though it might be an issue, it's probably not high on their list of problems. No rush though, I'll see what they tell me.

 

Plus I learned they have an annual community recycling event in July.

 

I wonder if it turns out I should just pour it down the drain, if I would be better off using it once and then pouring. That way I might pour more often, but it still wouldn't be THAT often and the fixer would have a lot less silver in it (from only 1 roll). Maybe it would be be the same deal -- 2 12oz pourings of 1 roll's worth vs. 1 12oz pouring of 2 rolls worth? And I could dilute it further before pouring in either case. Or maybe there is something I could mix it with before pouring, though I'm not sure what. I watched some more videos, and one of them poured a couple of chemicals into the fixer and seemed to precipitate most of the silver down to the bottom of the jug (it was a clear plastic jug) and then they poured off the stuff on top. I think they went on to pour the silver powder though some kind of sieve and then reclaim it somehow. But even if I didn't reclaim it, that precipitate looked pretty small and they were doing it from some kind of industrial system that had a LOT of silver in it relatively speaking.

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That seems more helpful if you’re setting up a business to do photoprocessing professionally. It’s hard to parse that for what the individual should do. On the one hand, someone doing 1 film a week is probably not expected to run his processing like a commercial photoprocessor. On the other hand, there probably ARE some recommendations, whether nationally or locally, that do apply ... maybe. I looked at the EPA as well, and like Alan’s document, it’s mostly about regulating people who do this professionally and whose output is heavy enough to really cause a health hazard, or at least a hazard to the water processing of the local water plants. But even the document I found locally was a lot more worried about paint and batteries and weed killers and insecticides, etc.

 

We all know that technically the silver is potentially harmful, at least to water and sewage treatment, but I guess the question is whether it’s really bad enough that a gallon two from a private household, or 12oz a week poured down the drain is really something the local water treatment folks are going to actually bother regulating. And there is always the public disposal day next July.

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