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What is the best way to dispose of used alcohol cleaner? Evaporate, Burn, Flush, ...? Answered

My electric razor cleans itself with alcohol. I need to change the fluid every few months. What is the greenest way to dispose of the dirty alcohol? I can't decide if it is better to flush, burn, or evaporate it.

I think it contains some methanol (probably  - it is 'denatured'). The can doesn't say what the denaturing agent is. It is sold as shellac thinner and stove fuel. It also includes a small amount of d-Limonene (orange terpene), plus the whisker residue.


I can't in good faith actually recommend that anybody pour chemicals down the drain but for reasonably small amounts (say < 1/2L) I wouldn't sweat it too much unless the chemicals in question are

a) halogenated (eg: chloroform, dichloromethane, tetrachloroethylene, freon [say from paint strippers, dry cleaning fluid]), or
b) contain heavy metals especially mercury

as these two classes in particular are persistent environmental pollutants. Ethanol/methanol/acetic acid, that kind of thing could reasonably be considered biodegradable. I would not drive to Pier 39 and force feed a liter of acetic acid to a baby seal, but with high dilution you are effectively dumping salad dressing down the sink.

I'm also the safety officer for my lab (ha!) so I know a little about the inner workings of waste disposal. Wastewater that goes down the drain goes to a large pre-treatment tank where it is checked for pH and heavy metal content before getting discharged. Periodically the MWRA comes by and audits our wastewater and they are specifically looking for items (a) and (b) mentioned above.

In California, the last lab I worked in had a similar arrangement, where Santa Clara County EH&S doodz would come by and test the water monthly. There, they were obsessed with chloroform and dichloromethane content. You could dump ethanol down the drain all day and nobody would notice or care (and if they did, it was not because of toxicity issues but because it is flammable).

The ironic thing about collecting hazardous waste and taking it to a proper chemical disposal place is that ultimately it all just gets incinerated. So even in a best case scenario it's all going to CO2. I would definitely not try to burn it myself, too cumbersome and dangerous. Letting it evaporate doesn't seem like a much better solution.

p.s. - I have a BS and PhD in organic chemistry if that earns me any clout

Excellent. I was hoping I would attract a reply from a chemist. Thanks for the info. I'm only trying to dispose of 1/4 cup of fluid. I think after straining out the hair, and composting it, I think I'll probably burn it.

Me renting a car to make a trip to the dump to dispose of such a tiny amount would be a bigger waste of resources. It should be considered for someone with a larger amount though.

I agree with Tabatron22 for the most part. Do not pour any down the drain. it is a mutagen. The best way I have found is still burning since the evaporation just puts it into the precipitation cycle. It is nasty stuff. read this;

New Jersey Dept of health MSDS on ISO


I don't want to go into too much detail at the moment but i would recommend making a distiller so that you can reuse the alcohol. Also if you happen to have an alcohol stove, or know someone who does, the distilled alcohol can be used as fuel. Of course you could always poor it down the drain since it contains no hazardous chemicals but some people might consider that wasteful.

Note: If you decide to go with the distiller option, there are several instructables that explain how to make one.

I'd say BURN....
Cooler and wouldn't hurt our waterways...
10mL of it can kill you, then how much those small fishes?

Why not save it till you have several ounces, filter it  through a coffee filter into a jar  or bottle.  You can then use it for other cleaning projects.  Waste not, want not.  I love to recycle.

I posted this question to a mailing list I'm on, and received this response and counter-response:
For alcohol, preferably performed outdoors.

A metal dish or similar fireproof container

Pile a bunch of salt in the dish
Pour the alcohol onto the salt
Ignite cautiously
Supervise until the fire goes out. Careful, it is often a hard-to-see blue flame
Repeat as necessary

I think dude is much more likely to burn down his property with your back yard fire trick. If you had a bottle of 91% rubbing alcohol to get rid of, would you really do that? I think most people would flush it down the toilet...

Burning outdoors is far safer than flushing especially if your wastewater system has a lift pump downstream of you. Pouring it on a pile of salt makes the whole thing quite manageable and controlled. This also works well for organic paint solvents like turpentine.

Evaporation by, say, dumping onto a sidewalk, is also acceptable for reasonably clean solvents, but can contribute incrementally to photochemical smog which is why burning is better.

Just the kind of responses I was hoping to get. I knew the Instructables crowd would know what is best. I'm going to give the best answer to the Organic Chemist, just because I like all of the chemical details :-) . This salt procedure is another brilliant addition to the solution (for disposing of my solution). Thanks.

Don't know if you are still reading responses but it appears that the very package you purchased gave you your answer ( Stove Fuel)....   burning less than a quart of methanol wil have negligible environmental impact.

Thanks. Yeah, it does burn clean, but it is only the solid residue that I'm sure of. I didn't know what kind of gasses were released during burning, and maybe the gasses from evaporation would be safer. It is a tiny amount, but I think we all need to be aware.

Well, the SFPUC doesn't want anything but water and human waste down the toilet.  Evaporation and burning seem like not great alternatives, and there would be some toxic sludge left afterward.

The best thing to do is to save it up (Along with your bold batteries, old paint, and fluorescent lights) and take it down to Recology's hazardous waste facility.  Yeah, it's in a crappy part of town, right near Candlestick, but if you save all your stuff up you should only have to go down there once or twice a year.

I don't have a car to go to the waste facility. Cole Fox Hardware will recycle flourecents, batteries, and paints; but not alcohol. Whole Foods SOMA takes used cooking oil.

Even though alcohol is a natural product (fermentation) and terpenes are distilled from orange peels, it still felt wrong to flush it.

It doesn't leave residue after burning - except the hair and skin sells.

Use a coffee filter to screen out the solids, whiskers, skin cells, and what not. 

Then pour the filtered liquid into the gas tank of your car, so that you can burn it with the rest of the fuel, and thus covert some of its enthalpy into useful work.

Note: If you are reluctant to try this because of fears that it damage the car's engine, then you should try it out on a friend's car first.

Oh, I forgot about the dirty coffee filter, plus solids.  To be green, this answer has to look at the process in its entirety.  You can burn the used filter, or put it on the compost pile, or burn it and put the ashes on the compost pile, etc.

San Francisco has home compost pick up. There is a special trash can for organic stuff like food and dirty napkins. I'd just put the coffee filter in there.

What I don't have in SF is a car! That is a brilliant idea though.

Awesome.  The pealing bells in the video were nice - I hope that wasn't just a TV.

No, they were real - it was the local bell-ringers practising.

Flush it, you can't have that much.


Around here, they are working on a way to make it illegal to flush foreign chemicals down the loo, but it would be kind of hard to regulate  (camera's in the bathrooms?).

It's bio-degradable.
I would hope The Man hadn't installed a camera in your bathroom?!


I hope that they didn't even  more so then you do   LOL 

It's illegal to pour stuff like that down the drain where I live, maybe you could try mixing it with orange juice and drinking it. It's not illegal to pour a little bit of alcohol down your throat where I live. ; ) Seriously though, I don't know what your plumbing is like there, or if you would pour it down your sewer (your house waste pipes) or the stormwater drain (out in the street), but a build up of explosive vapours in a confined space is not good. See if your local dump will accept chemical waste. Or maybe ther is a waste chemical collection point somewhere in your town.

denatured alcohol is poisonous....

DONT DRINK IT!! I think rubbing alcohol is poisonous to you.


             i vote for burning, take 30 sec. and check out any alcohol stove site !

             - being able to assemble, and use a d.i.y.  alcohol stove is one of those
nice to have crafty skills that should be a quick study for you !
                                                                                        Best ! Big Al 1048

Fire makes it better.

I would let it evaporate outside, unless you are a pyro and just want to burn it for the sake of burning it. It may leave residue behind though cause there is other stuff in it, but I would just probably rinse the container off afterwards.

It'a perfectly fine to pour small amounts of alcohol down the drain.

I would filter it through, say, a coffee filter. Then you can reuse it or burn it  in an alcohol burner.  Evaporation is OK too.