Cleaning veg oil out of steel drums

I just obtained some used food-grade 55 gallon steel drums to use for rain barrels. They previously contained sunflower oil. I’m looking for suggestions on the best way to clean them out prior to water collection. I plan to use them strictly for watering the garden, not for drinking.

The guy I bought them from said he just pours a little hot water in them, seals the lid, and lets them sit overnight, which I guess steams them clean. Then he pours the water down the drain. Northern Colorado nights are cold this time of year, and I really don’t have room to bring them inside. Also, city municipal water And sewer departments frown on dumping any type of oil down the drain, as it congeals and can trap other waste materials, potentially clogging the sewer pipes.

Dishwashing detergents, such as Dawn will break down grease and oil, at least long enough to separate it from your dishes, but I’ve read that the oils can re-congeal later. It would be nice to be able to compost what I dump out, but I don’t want to add a lot of soap or oil to the pile. Small amounts of either seem to be tolerable, but I don’t want my compost to go anaerobic.

Are there any organic soaps (Dr. Bronner’s?) that will permanently break down vegetable oils to a compostable or flushable form, or is this too much to ask?

My less elegant idea is to clean it out with Dawn and minimal water pour it into a 5 gallon bucket lined with a kitchen sized trash bag, and leave it outside until the water evaporates. Then throw out the bag.

I welcome any other ideas.

Thanks,
Jeff

How long before you need them? The oil will degrade if you fill them with water or compost tea or anything organic it'll take a few months though.

Welcome to permies J Stark!

When I have greasy stuff, my first approach is to wipe up as much of the grease as possible with newspaper, old paper napkins or cotton rags. If you're leaving the lid on, I'd put the absorptive material in a container and carefully prop the drum up so it will gradually drain. Even if it's cold out, putting it where the sun will hit it will help.

Once you figure as much has drained as possible, you can decide what to do with the greasy material - compost, burn (great fire starter), or garbage - possible recycle if you get "green" pick-up of food scraps.

Do you expect to be able to fill the drums to overflowing before needing the water? If so, the oil will float on the water, so you could just let it overflow so long as you won't be bothered by a little oil in the overflow location (this is assuming you've done my first approach already.
Personally, I haven't found soap all that helpful with grease unless you can really scrub it, which you can't do if it's the inside of a closed barrel. So long as most of it's out, I suspect any that's left won't hurt your plants/soil if you distribute it well.

I probably have the same barrels, but mine contained coconut cream.   I used Dawn dish soap and a rag with some warm water, then rinsed them out with the hose.  Of the 15 barrels only one had to be washed a second time.

I would take them to the self-service car wash, and bring a scrubber with a long handle so you can scrub out the bottom without having to stick your arm way down in there.

Lye does a real good job of removing even polymerised/hardened veg oil.

Mopping it up with something burnable first sounds like a good idea.

Jay Angler's advice is spot on. That's what I would do. If handled smartly, this waste material can be a resource.

BTW, ever make soap?

If you're wanting to go all-natural. I'd fill it with water and a good amount of wood ash (or make an ash paste and scrub if you're so inclined). Agitate, leave for a day or two and drain somewhere that can take decently high pH water (Compost pile, random patch of dirt). The KOH in the ashes should react with the fats to make a rudimentary soap which will dissolve in the water and easily break down later.

Nick Williams wrote:If you're wanting to go all-natural. I'd fill it with water and a good amount of wood ash (or make an ash paste and scrub if you're so inclined). Agitate, leave for a day or two and drain somewhere that can take decently high pH water (Compost pile, random patch of dirt). The KOH in the ashes should react with the fats to make a rudimentary soap which will dissolve in the water and easily break down later.

My knowledge is rudimentary, but it's my understanding that heat is required to make the soap reaction happen. Fresh wood ashes would be a good scrubber though. Then maybe rinse and drain into a vessel that could be heated?

Edit: I would worry that any retention time involving wood ash will quickly induce corrosion in a metal barrel.

Douglas Alpenstock wrote:

Nick Williams wrote:If you're wanting to go all-natural. I'd fill it with water and a good amount of wood ash (or make an ash paste and scrub if you're so inclined). Agitate, leave for a day or two and drain somewhere that can take decently high pH water (Compost pile, random patch of dirt). The KOH in the ashes should react with the fats to make a rudimentary soap which will dissolve in the water and easily break down later.

My knowledge is rudimentary, but it's my understanding that heat is required to make the soap reaction happen. Fresh wood ashes would be a good scrubber though. Then maybe rinse and drain into a vessel that could be heated?

Edit: I would worry that any retention time involving wood ash will quickly induce corrosion in a metal barrel.

The reaction is definitely faster at temperature, but it isn't strictly necessary to be hot. You're not really trying to make "Soap" in this case, you're just trying to saponify the oil enough to make it soluble. Your fingers will feel oily if they ever get washing soda or lye on them, as it literally saponifies the oils in your skin, even at room temperature.

Interesting. Thanks!

Thanks for the tips. I especially like the idea of wiping the barrels out with newspapers and using them as fire starters.

Can’t let the barrels overflow because the dogs will get into the stuff.

I mentioned soaps and detergents, particularly Dawn, because that’s what works best for cleaning oil soaked wildlife. We use it at the raptor rehab center I work at for the occasional bird that lands in an uncovered oil tank, thinking it’s water.

I didn’t think about the oil breaking down in the barrels, but the compost tea idea makes sense. I might have to make some tea in the first fill of each barrel since it’s getting close to planting time for some crops. The sunflower oil will be very dilute, especially after draining and wiping it out, so the micro-critters in the tea won’t get too overwhelmed. It’s going directly to the garden, so there’s no chance of ruining a whole bin of compost with a sudden influx of straight oil.

Thanks again guys!

J Stark wrote: I especially like the idea of wiping the barrels out with newspapers and using them as fire starters.

Please use caution! Veggie oil isn't particularly "volatile", but fire is a "useful danger" and I'm not clear on the size of this cleaning job. If you end up with a fair bit of oily paper, consider storing it in a metal garbage can with a lid until you need it. Hubby uses veggie/animal fats in our wood-stove, but he limits the quantity he puts in any single fire.

Many different people read these threads over multiple years, so even if the OP knows all about what I just wrote, someone new to wood stoves may not, and I want to keep *all* our permies safe and sound!

And also wrote:

I mentioned soaps and detergents, particularly Dawn, because that’s what works best for cleaning oil soaked wildlife. We use it at the raptor rehab center I work at for the occasional bird that lands in an uncovered oil tank, thinking it’s water.

Rules vary - saving a life is worth using a product that may not be as biodegradable as we'd like. I've been led to believe that a bird can die pretty quickly from an oil dunking, and a wild creature isn't going to be as tolerant of "multiple wipings with cotton rags" or "being left to drip" as a steel drum is. To me, the more oil you can get out before resorting to cleaners, the less negative impact on the environment if only because of the embodied energy in the manufacture and shipping of the detergent. R Ranson has an excellent e-book called "Clean with Cleaners you can Eat" and it's great reading for anyone who wants to move towards a smaller foot-print on this wonderful planet.  ( https://permies.com/t/edible-clean )

Good call, Jay. I don’t have a wood stove or fireplace, and the amount of oil in the barrels is minimal. I just intend to use the saturated papers to start fires in a steel outdoor fire pit. I wouldn’t burn oil indoors anyway.

My solution:
First I propped up the bottom of each barrel with the open end resting on a 5 gallon bucket lined with a plastic bag to drain what I could. I got over a gallon out of two barrels. It took the better part of a day because the stuff was like molasses and it’s been pretty cold outside.

Then I partially filled a 5 gallon bucket with hot water and poured it in. I sprayed the sides down with Simple Green and put the lid back on the barrel and let it steam for a few minutes.

Using a long handled scrub brush while the water was still warm, I scrubbed the inside clean in a matter of minutes. The Simple Green broke down the oil, making it safe to dump down the toilet and into the municipal sewage system.

It was a lot easier than I anticipated.
Thanks for all your suggestions.

J Stark wrote:First I propped up the bottom of each barrel with the open end resting on a 5 gallon bucket lined with a plastic bag to drain what I could. I got over a gallon out of two barrels. The Simple Green broke down the oil, making it safe to dump down the toilet and into the municipal sewage system.

Municipal systems don't like a lot of oil and grease, so I'm sure they'd be pleased if they knew the effort you'd made to get that first gallon out of there!

Will ants take the stuff? By laying them out for a few weeks?