Are there B&W Chemicals that are Safe for Septic Tanks ?

Jersey Vic · Mar 4, 2011

A friend lives one house out of town and needs to get a darkroom going again.
Are there any chemicals he could use and dump down his drain into his septic system ?

moose10101 · Mar 4, 2011

The fixer is the main concern; if he recovers the silver, that shouldn't be a problem. If he really wants to be safe, he could develop with caffenol and find some place to process his spent fixer.

ntenny · Mar 4, 2011

This question comes up every so often (a while back I was the one asking, and I think I got pointed to about three hundred old threads in which everyone disagreed with everyone else). For what it's worth, here are the conclusions I came to:

1. The amount of chemicals used in a home darkroom likely will not do any appreciable damage to the function of a septic tank.
2. Silver is the biggest potential problem in that respect. (Used fixer is the big issue here.)
3. Hydroquinone is the nastiest common developing agent as a general pollutant; I expect metol is second. (Glycin and pyro have scary reputations, but never having used either I haven't investigated much.)

Where I've ended up, with a pretty clear conscience and a working septic tank, is that used developer (other than Caffenol) and fixer go to hazmat; the first rinse from a hydroquinone developer goes to hazmat; other rinse water goes through steel wool to try to capture any stray silver, then down the drain. This regime produces hazmat material slowly enough that I find it reasonable to take them a few bottles every few weeks.

Other people have taken much less conservative approaches and said that nothing bad seemed to happen; it seems like the septic system doesn't break easily in practice, but it's hard to judge what a "safe" amount of pollutants is in the larger scheme of things.

-NT

MaximusM3 · Mar 4, 2011

Jersey Vic said:
A friend lives one house out of town and needs to get a darkroom going again.
Are there any chemicals he could use and dump down his drain into his septic system ?

I dump everything there... well, within reason

JOSarff · Mar 4, 2011

The biggest danger to a properly functioning septic system from a home darkroom is the ammount of water put through the system. Dilution of the digestive flora in the septic tank will be the major problem.

If your running high volumes of water make sure to charge the tank with yeast (c ouple of packets or cakes if you can find them) or bacteria from the locol hardware store monthly.

mgb74 · Mar 4, 2011

This does come up every so often and often argued. The issues are chemicals that effect the operation of the septic system, chemicals that enter the ground through the septic system, and the volume of water that may effect operation of the septic system (this last point is a sizing issue).

It seems to be the consensus that all but fixer (containing silver) is OK. I take a more conservative approach and collect used developer, stop bath, fixer, wash water (if using Ilford method) or first rinse (if not using Ilford method). But I have the luxury of access to a municipal system where I can dump what I collect. My volume is such that this is feasible. Also, our septic tank is sized large for the number of people currently using it.

To those who have dumped chemicals and not had any problems, I ask how do you know? Unless you test the ground by your drainfield, you're really just guessing.

Gerald C Koch · Mar 4, 2011

The safest commercial developers for the environment are those which use ascorbic acid (vitamin C) such as Xtol. This is why they were developed to replace hydroquinone based ones.

Pgeobc · Mar 4, 2011

>The amount of chemicals used in a home darkroom likely will not do any appreciable damage to the function of a septic tank<

Anything that contains hexavalent Chromium is toxic to septic tanks and water supplies in the parts-per-billion range. I would never dispose of any Cr+6 in anything but a toxic waste dump. A part per billion is something like, in ball-park anaogies, a jigger of whiskey in a train-tank car full of water.

Silver salts are also mildly toxic, but at a different level. If one wanted to be kind to his septic tank, he would not dump anything with dissolved silver, either. An exception might be the Silver halides, e.g. AgCl, which is so insoluble as to not matter. However, much of the unused silver in film is dissolved out and, therefore, available.

Gerald C Koch · Mar 5, 2011

Septic tanks contain a large ampunt of sulfide ion which causes many metals like chromium and silver to be deposited as highly insoluble sulfides. Such metals are not going to escape into the environment.

mgb74 · Mar 5, 2011

Gerald C Koch said:
Septic tanks contain a large ampunt of sulfide ion which causes many metals like chromium and silver to be deposited as highly insoluble sulfides. Such metals are not going to escape into the environment.

Will they sink to bottom in a septic tank? If so, they'll be sucked up when the septic tank is pumped out (every 1-3 years) and presumably be treated. If not, they'll go out through the drainfield and into the surrounding ground.

ntenny · Mar 5, 2011

Pgeobc said:
Anything that contains hexavalent Chromium is toxic to septic tanks and water supplies in the parts-per-billion range. I would never dispose of any Cr+6 in anything but a toxic waste dump.

Cripes, neither would I. But there's no hexavalent chromium anywhere in normal b&w processes, is there?

-NT

removed account4 · Mar 6, 2011

waste haulers are cheap and easy, and you don't have to lug bottles or buckets of spent chemicals.
it takes nearly forever to fill up a 15gallon or 50gallon roadside drum.
i've used one for about 12years.

Gerald C Koch · Mar 6, 2011

Septic tanks are designed so that incoming raw sewage does not immediately go to the drain field. That is the intended purpose to allow sewage to be digested by the bacteria present in the tank. This delay allows heavy metals and other materials to settle out.

removed account4 · Mar 6, 2011

the problem is that in many cities and towns
the laws that govern the discharge from one's home
into their septic system or municipal sewer treatment plants are all different.

this topic has been beaten to death here in many threads over the years
there are folks that claim it is harmless and others that say not so ...
sadly in a poll i made a few years ago, close to 70% of the people who responded
just poured all the photochemistry down the drain without a second through ...

oh well ...

2F/2F · Mar 6, 2011

Where does your friend live? He should contact his local or county government to inquire about hazardous waste disposal options. Most counties have ways for people to turn in their hazardous waste to be properly disposed of. All your friend would need to do it keep the spent chemicals separated and labeled by product name in bottles, and take them in along with all the other household hazardous waste that he should be taking to the waste center anyhow (oil/solvent rags, oil filters, paint/varnish/solvent cans, batteries, electronics, cleaning products, etc.). This is all stuff that none of us should be throwing away.

Pgeobc · Mar 6, 2011

>Such metals are not going to escape into the environment. <

From my time spent doing drinking water, waste water, and sewage analysis, I can tell you that statement is not correct. Sewage treatment plants can treat for hexavalent Chromium, but only if they know that some is coming ahead of time and have the chemicals ready. It can kill the whole process, bacteria and all, and it will take quite a bit to get things back in order.

Save your septic tank system and your town's/city's system by disposing of this stuff properly.

Another area of photography chemicals to look for is Selenium salts. Although the health food nuts claim that they are good for you and sell you supplements, anything more than trace amounts can be a problem.

Pgeobc · Mar 6, 2011

Nathan,

>But there's no hexavalent chromium anywhere in normal b&w processes, is there?<

Yes, but it is not an everyday chemical, either. I think that it is used as a reducer or in direct B&W positive processes, maybe both.

ntenny · Mar 6, 2011

(quoting someone else first; Gerald Koch, I think)

Pgeobc said:
>Such metals are not going to escape into the environment. <

From my time spent doing drinking water, waste water, and sewage analysis, I can tell you that statement is not correct. Sewage treatment plants can treat for hexavalent Chromium, but only if they know that some is coming ahead of time and have the chemicals ready.

A fair point, but only relevant to the serious nasties like Cr6 that can't be routinely treated out, right? From the perspective of the septic tank, as long as the metals turn into something insoluble and have settling time, they're going to end up in the pumping truck rather than the leach field.

Of *course* anything that will mess up a sewage treatment plant (or get through the treatment and become an uncontained pollutant) needs not to go in a septic tank, because the tank contents will eventually go through treatment. But if we're talking about "standard" b&w processing---developer, stop, fixer---then I'm pretty sure the only substance at issue for this discussion is silver. (Selenium becomes relevant for people who tone with it, but I have no idea how it behaves in a wastewater plant---personally, if I used it, I'd take the results to hazmat.)

Ammonium and potassium dichromates are a flavour of hexavalent chromium, if I'm not mistaken, which makes this discussion relevant for people who do cyanotypes. I'm not sure what happens to the chromium in the course of the process, though---does it end up in the rinse water, or stay in the paper, or something more complex than either?

-NT

removed account4 · Mar 6, 2011

john_s · Mar 7, 2011

Dissolved silver will combine with sulfur-containing compounds (no shortage of them in a septic tank) and will become inert and insoluble AgS.

r-brian · Mar 7, 2011

JOSarff said:
The biggest danger to a properly functioning septic system from a home darkroom is the ammount of water put through the system. Dilution of the digestive flora in the septic tank will be the major problem.

If your running high volumes of water make sure to charge the tank with yeast (c ouple of packets or cakes if you can find them) or bacteria from the locol hardware store monthly.

Adding yeast or septic tank products such as Rid-X are:
1. A waste of time and money.
2. At best, does absolutely nothing.
3. May actually do harm.

A study was done by the National Small Flows Clearinghouse (www.nesc.wvu.edu) a few years ago and that was their conclusions.

What effect do darkroom chemicals have on a septic system? I don't know because it has not be studied. I do know that dumping simple household products can affect the system. A gallon of bleach can upset the tank for a day or two, which could cause solids to exit the tank and cause premature failure of the drainfield. Multiple loads of wash can cause a hydraulic overload on the tank and drainfield, again causing premature failure.

What effect the chemicals have, I don't know. Do they stay in the tank or flow thru to the drainfield, I don't know. Do they enter the groundwater, I don't know. You would think the technical person for the septic tank program for the State of New Mexico would know, but I don't know. I do know that products and compounds that are routinely discharged into septic systems and sewer systems (prescription drugs, hair care products, laundry products) are showing up in the environment with increasing frequency. Again, go to the NESC site and see what they've studied and found.

jeffreyg · Mar 7, 2011

I have a home darkroom and septic tank and drain field. Although I don't use the darkroom every week I have used it regularly for thirty-five years with no apparent problems. The plants and grass over the drain field grow beautifully. I have only used chemistry for b&w and pt/pd. The system is for our entire house so the amount of water from the darkroom is small compared to the other water use.

http://www.jeffreyglasser.com/

Gerald C Koch · Mar 7, 2011

Pgeobc said:
>The amount of chemicals used in a home darkroom likely will not do any appreciable damage to the function of a septic tank<

Anything that contains hexavalent Chromium is toxic to septic tanks and water supplies in the parts-per-billion range. I would never dispose of any Cr+6 in anything but a toxic waste dump. A part per billion is something like, in ball-park anaogies, a jigger of whiskey in a train-tank car full of water.

Silver salts are also mildly toxic, but at a different level. If one wanted to be kind to his septic tank, he would not dump anything with dissolved silver, either. An exception might be the Silver halides, e.g. AgCl, which is so insoluble as to not matter. However, much of the unused silver in film is dissolved out and, therefore, available.

What always seems to get lost in these (all too frequent) APUG discussions about darkroom chemicals and septic systems is that a septic system is a highly reducing environment full of sulfide ion. Any hexavalent chromium is going to be rapidly reduced to either the trivalent or divalent state and depositied as highly insoluble sulfides. None is going to get into the ground water. They will remain as a sludge until the tank is pumped out. The same goes for silver, selenium, and most other metal ions. Sewage treatment plants have a similar reducing environment.

Too frequently the US government employs people who have little or no training in the fields that they seek to oversee. These peope often set up mindless regulations that have little application to the real world. It is ignorant of the governemnt to worry about hexavalent chromium in environments where it cannot exist. While not the government per se, I am reminded of the BP document warnng the company to be concerned about the safety of walruses in the Gulf of Mexico. Unfortunately our culture has been anti-science for many years and we are now paying the price.

Are there B&W Chemicals that are Safe for Septic Tanks ?

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