Environmental Concerns -- Darkroom Chemicals

Discussion in 'Film and Processing' started by sarah_fox, Apr 5, 2013.

  1. So I've done some searching and find material relating to situations rather different from mine. Mine is an extremely sensitive case that perhaps deserves its own thread. Hopefully you chemistry types can help me.
    I'm considering putting my darkroom back together in a new (to us) home. However, I'm mindful that we have a septic system on a hillside that leaches down into a tidal pool that is an estuary where a large population of fiddler crabs hangs out. These crabs are eaten by all variety of water fowl. So I'm concerned that whatever I put down a drain goes fairly directly into the local wildlife.
    My question should be obvious. As there is no waste treatment plant to take care of my tiny bit of pollution, so I have to do this myself. I am mostly interested in developing B&W film. Although I might do some printing, I suspect my workflow would be mostly digital, beyond the film. I'm uninterested in using toning agents. I need to determine the following:
    • What is safe to go down the drain as it is? I'm thinking stop bath is fine -- acetic acid.
    • How can I modify/treat any chemicals that are unsafe in their exhausted form? For instance, I know I can reclaim silver electrochemically.
    • What chemicals cannot be modified/treated adequately and must be disposed of elsewhere?
    Thanks for your help!
  2. While true silver can be collected electronically, the best systems likely leave a residual silver content of more than 1000 milligrams per liter. Most municipalities set a lower silver discharge level. While local regulations vary considerably, generally intentionally diluting photo effluent with a water volume greater than normally required for the photo process, is not allowed.
    Most small photo operations are better suited to recover silver using ion exchange. The equipment for this operation is a plastic bucket filled with iron-wool. The silver-bearing solution is allowed to trickle into the bucket. The overflow will be within the silver limits for most municipalities. What happens is, silver solution contacting the iron wool, exchanges silver for iron. The silver residue falls to the bottom of the bucket as a reclaimable sludge. Most labs will use a two bucket system to insure low silver effluent. The silver bearing solution is either gravity fed or pumped at a slow trickle into bucket 1 and then bucket 2 then to the sewer. In most cities, silver recovery services and equipment are handled by x-ray supply companies.
    A small operation is better served by ion exchange only. This is true because they are very efficient. However the silver recover by ion exchange is low grade and more costly to refine. Silver recovered electronically is high grade thus more marketable. Those labs that use electronic devices usually employ a duel system, electronic followed by ion exchange.
    As to acidity or alkalinity, the developers are generally alkaline, the stop and fix are acid. Discharging all solutions to a single source most always results in a near neutral effluent, as to pH.
    Kodak and others, who have studied discharging to a septic system, advise against. However privately they proclaim photo effluent as being benign. Even so, they wave a red flag because a septic system is dependent on microorganisms that digest waste material. The concern is: photo effluents initially harm the naturally occurring biomass. However, every study has shown a rapid culture of photo effluent resistant biomass quickly forms restoring the septic system to full function.
    The real problem is not the chemicals being inputted, but the belief by municipalities that this stuff is bad. Therefore, if anything happens, not your fault, you will be blamed. Hence, nobody will advise the use of a septic system for photo effluent.
  3. Unless you are using large amounts of
    chemistry and/or are right next to the
    water I doubt your darkroom work will
    have any effect. As a kid I did a fair
    amount and it went into a septic tank
    uphill from a 5+acre pond. We never
    noticed any effects and had a biologist
    in the neighborhood who kept an eye
    on things. I probably used less than 10
    gallons of developer and fixer in a
    years time. I'm sure there is a hazmat
    collection outfit in your area that could
    take it off your hands

    Rick H.
  4. When I lived in a rural area up until about 10 years ago I was concerned about my b&w darkroom chemicals. Besides two septic tanks we also had two water wells and were within 100 yards of a lake/reservoir with sandy loam soil. We had tests run by the county agricultural extension office and everything tested fine.
    Most common developers and fixer are no more harmful than most common household cleaning products - and probably less harmful in the small batches produced by most home darkroom hobbyists.
    Most folks I know of just use steel wool to collect silver sludge from exhausted fixer.
    Another way to minimize the offal is to use a recyclable/reusable developer such as Diafine. It's not a great developer for all films but is very good with a small handful of film types - notably Tri-X.
    Selenium toner can be reused quite a bit and finally taken to a hazardous waste disposal center.
  5. Again, nobody will give you thumbs up.
  6. Thanks, guys! You've given me some comforting practical advice. (And thanks for the additional info by email!) So I gather the only bad boys in the mix are heavy metals, and the only heavy metal I'll be using is silver. The reclamation buckets seem a very easy method. However, it would probably be easy to plate the stuff out. All I'd need is a power supply and a couple of electrodes, right? :)
  7. And think of all things you can silver plate!
  8. In theory using the electric silver plating method sound best. This is true because the silver will highly purified and thus marketable. The downside is, most unlikely that effluent willnot test out below 1000mg per liter. On the other hand, the effluent from a properly installed ion exchange (iron wool sytem) will likely be 1 or 2 mg per liter. The federal guideline is 5mg per liter. Some local requirements are 0.5mg per liter.
    All very sad because it has been proven over and over again that the silver in the effluent of large or small photo operations are not toxic for silver. This is true because the fixer of both the color and black & white processes is high in sulfur. The sulfur always combines with silver to form silver sulfide, one of the most inert compounds known.
    The problem is, silver is classed as a heavy metal along with chrome etc. These are highly toxic. Silver is toxic in ionized form but not as a compound of sulfur. To make matters more dreadful, a classic test for silver in effluents is to use nitric acid as a reagent. This is one of the few ways that will liberate silver from the sulfide and regretfully this results in a positive test for silver. The key reason the federal government continues to list photo lab effluent as toxic for silver is; most discharge will be to a treatment plant. The silver sulfide that results will fall to the bottom of plant tanks and remains until the plant's sludge is harvested for sale. If the nitric acid test is used, the sludge will test positive and the market value of the sludge is greatly diminished as this presumed to be ionic silver, a toxic. Over the years labs I managed were challenged again and again. I was forced to pre-treat using elaborate means to remove silver and oxygen demand and chlorine demand, the other two culprits. It takes a lot of time and money to defend against these issues.
    The home septic tank is just not a problem no matter color or black & white, the real problem is, if anything happens, your fault, nobody's fault, your it. They can and will come back downstream (all septic systems empty to a stream) and place the full blame on you. Now you face with the impossible burden of defense. It is the chemicals that nobody wants in their environment, no listening to reason, chemicals are bad news to most folks.
  9. You could also evaporate fixer and wash water and every so often take the residue to a disposal place.
  10. Why don't you collect it all in jars and drop it off periodically at your county recycling/waste depot where they accept old tires, paint, etc.?
  11. Well I have a gravel driveway and throw my exhausted chemical on the weeds and grass that inevitably are growing through it. Kills them every time. The water table is a long way below ground and I'm miles from any river so I can't see it harming the water. Wouldn't tell the local authority though.....
  12. The home septic tank is just not a problem no matter color or black & white, the real problem is, if anything happens, your fault, nobody's fault, your it. They can and will come back downstream (all septic systems empty to a stream) and place the full blame on you. Now you face with the impossible burden of defense. It is the chemicals that nobody wants in their environment, no listening to reason, chemicals are bad news to most folks.​
    You know.... This rings true. In these parts, we have what's called the Chesapeake Bay Act, which regulates vegetation, runoff, etc. alongside the Chesapeake Bay and its tributaries. (We do live right on the water, BTW. The darkroom would be about 120 ft from the estuary, and the leach bed is about 30 ft from it.) Even though the county dumps insane amounts of stormwater runoff from the streets into this estuary (eroded soil, motor oil, tire rubber, trash, pesticides, herbicides, fertilizer, and the dreaded "et cetera" class of compounds), the county gets all freaky with us if we prune a bush in our ongoing effort to get light to the groundcover, which holds the soil, thus preventing it from eroding into the estuary. There's no sense to it. So maybe it's best to let the dump (or a hazmat facility) deal with it. Why wrangle with bureaucrats?
    My remaining question is this:
    I presume the only problem chemical is the fixer. As you say, Alan, the developer and stop bath can be mixed together and more or less neutralized. I suppose I could titrate with a bit of sodium hydroxide or HCl to achieve a pH of 7. Would these chemicals, mixed, be problematic from a standpoint of environmental liability? Do I risk dealing with the same bureaucratic nonsense?
  13. Hi Sarah,
    First, the link I posted to the Kodak J110 publication is likely your greatest resource. Kodak published the J series (all now free on the internet), assembling the finest minds they could recruit from North American universities. What I am trying to say is, Sarah, don't pay an attention to me or photo pundits. That being said, silver should be your main concern and it is present mainly in spent fixer.
    I think you should know that silver metal is not particularly toxic. Consider silver tableware, silver body implants (bone replacement), silver swimming pool algaecides. Silver was used to purify water, silver medicines (burn victims), silver jewelry, silver electronic parts, silver in all black & white film and print, silver fillings in teeth, etc. To be toxic it must be ingested or absorbed and get in the blood stream. There have been about10 cases all cosmetic changes, all but one doctor induced and one nutcase who drinks the stuff. He professes that silver is medical wonder, his skin has turned blue and he is still alive and kicking. The culprit is ionic silver. Most silver in photo effluent is complexed with sulfur, plus some ionic silver. The ionic silver exits in our effluent for a few seconds and then unites with sulfur from the fixer to form an inert compound. Omit the fixer (rich in sulfur) and you still will get silver sulfide; only it will take a few more seconds to form. Photo effluent when all is comingled is pretty benign as to toxicity and pH (power of hydrogen).
    Now the best advice this curmudgeon can offer is, call a local X-ray service company. They can supply all necessary resources to handle you photo waste including haul away.
  14. Thanks, Alan! This is certainly a time-honored approach: Seek out someone else whose with proper licensing and certifications whose business it is to know the proper protocols, and rely on their services. Then if anything goes wrong, it's THEIR fault! ;-) That works.
    I've now Googled people who are blue from drinking silver:
  15. I would not throw any chemicals where an innocent animal might graze and get poisoned. If it will kill weeds, it's dangerous as heck. Our cat loves to go out and grass graze, so we don't use any fertilizers or weed killers at all. As Alan said, the silver in B&W developing chemicals is not so bad. There would not be many old photographers around if it were. By the by, for years I had chronic sinusitis and tried everything, but a few sessions w/ colloidal silver nose drops cleared it up. That's been nearly 15 years ago, and it has not come back since. It was probably a low grade infection, and the silver did it's job. Silver has a long history of successfully being used for wounds and as antibiotics. You have to be careful about what type of silver you're dealing with (I think the colloidal silver is silver salts).
  16. I saw a special on the Chesapeake, on PBS. Frank Purdue's son was throwing the chicken crap into the Chesapeake, clogging it up and it was growing bacteria.
  17. [Sarah] However, it would probably be easy to plate the stuff out. All I'd need is a power supply and a couple of electrodes, right? :)
    Oh, oh, get ready for a humbling experience. The difficulty is that you need a good supply of free silver ions in the immediate vicinity of the cathode, and these tend to disappear very quickly. The key is to have a large cathode surface and lots of agitation. The common machines during the minilab boom used rotating cylindrical cathodes to achieve this.
    An alternate method is to use extremely low current, but the electroplating takes a long time. A commercial outfit probably can't wait long enough for this, but many hobbyists can. There's a commercial unit called the "Silver Magnet" which apparently works along this line, so if you only process every few days, one of these might work ok.
    I think there ought to be a few revisions to what Alan has said. In my experience, an electrolytic recovery system can reliably get below 100 mg/l silver (not 1,000 as Alan has said). This is for terminal use on a C-41 type fixer; ideally you'll cut plating current below half near end-of-cycle and would continue until the silver plate begins to visibly darken.
    Also, Alan refers to the iron-wool method as "ion exchange;" more traditionally this is called "metallic replacement," with the term "ion exchange" reserved for systems using an actual ion-exchange resin in a sealed tank, along with a system for further treatment of the resin.
  18. Use caffenol which is vitamin c-citric acid and coffee grinds. Very safe for the environment.
  19. A tip of the hat to Bill C,
    Bill is correct, electrolytic silver recovery can lower the silver content to below 100mg per liter (1000 milligram mg is about the weight of a raisin). The electrolytic method uses electrical energy to plate out silver onto stainless steel plates. This is the preferred method in large-scale photofinishing and movie processing operations. Electrolytic is popular because the silver-bearing solution is circulated into an adjacent tank, de-silvered, then replenished. The restored solution is then returned to the working tank. The influx is about 2000mg per liter; the outflux is about 1000mg per liter. The silver harvested is about 98% pure.
    The pitfall of the electrolytic method is: the current needed to do the job correctly must be monitored and constantly adjusted based on silver content. If the current is too low, the silver harvest is unproductive. If the current is too aggressive, the harvested silver will revert to silver sulfide, which diminishes its value. Monitoring and adjustment of current is no easy task. In modern times, sensors are available, but they too require due diligence to maintain.
    If the goal is meeting environmental standards, electrolytic silver recovery must be followed by a tailing operation to achieve the required federal or local standard. The one-hour mini-lab never practiced recirculation of the silver-bearing solution.
    Labs using only electrolytic methods never achieved environmental compliance (5mg per liter or less). Other more efficient methods are but not limited to: chemical precipitation, ion exchange (using synthetic resin), metallic replacement (a form of ion exchange), or reverse osmosis.
    Metallic replacement is the popular vernacular, a synonym for ion exchange. This describes a chemical process whereby an ion in one compound is replaced by a different ion. The chemical description is:
    Silver thiosulfate Complex + Metallic Iron = Metallic Silver + Ionic Iron + thiosulfate
  20. Thanks, guys! :)
  21. People have had home darkrooms for many, many years. How often have you heard of a problem with a septic system being attributed to darkroom chemicals being poured down the drain in photographic literature or elsewhere? As for contaminating groundwater, the soil filters toxins out of the the effluent before it gets to the groundwater. By the time the toxic effluent gets to the groundwater, it is fit enough to drink due to this filtering action. This is how septic systems work. Otherwise, there would contaminated groundwater everywhere. Not that I am against silvery recovery or waste disposal, but that the small, home darkroom worker need not worry.
  22. I believe the bacteria will eat up the developer reasonably fast. Thiosulfate is reasonably safe, and will oxidize anyway to something like sulfate. Use the previously mentioned methods to get out much of the silver, what's left probably won't hurt anything.
    I don't believe that a home darkroom generates enough silver to sell, in normal use.

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