Composter Project

[J.J.]

We have several 55-gallon steel drums at our disposal.  If we don't do something with them, they'll end up "in the disposal."

I like the idea of making a composter to have at the space to handle the grass clippings and other vegetable matter.  Other folks like the idea of perhaps making their own as well.  So, let's talk.

[Eoin Ross]

Links for ideas...
https://www.pinterest.com/pin/20195898300189265/

http://www.instructables.com/id/DIY-Compost-Tumbler/step2/Here-is-my-55-gallon-steel-drum-Notice-the-1-12-ho/

https://vamfun.wordpress.com/2012/07/28/solar-robotic-dual-55-gallon-drum-composter-vex-lancer-bots-project/

[Adam Russell]

What was in the drums previously?

[Eoin Ross]

I think Andrew said it was machining cooling fluid.

[Adam Russell]

Let me preface this by saying I'm not a steel drum expert and these are my uneducated opinions =P

1. I think safety of potential contaminates should be explored.

2. Won't these things basically turn to piles of rust with compost/water in them?

Just my thoughts in regards to composting.  There are still tons of cool things you can do with steel drums...

On Wednesday, May 13, 2015 at 12:53:00 PM UTC-5, J.J. wrote:

[Jesse Collier]

The majority of advice I found was to only use barrels that previously were considered food grade for composting barrels, as the end product is typically going to be used for food.  And if a steel drum were used for composting, I have no idea how long it would last until it deteriorates.  Plenty of people on the internets use them for composting but I've never read a 5 year later follow up.  I occasionally throw rusty metal bits in my composter and rarely see them again when I go to sift so I'd say it may last a while with whatever coating is on the inside but it'll break down eventually...

I built mine 5 or 6 years ago from a plastic 55 gallon drum and PVC, on a stand high enough to fit my wheelbarrow under.

Which worked great until I decided I needed to sift the fines to determine what was ready for use and what needed to go back in to cook longer.  I made a trommel sifter based on an instructable and the process of removing product from the composter now, to be placed in the sifter, is a pita.  The door is too small, and with the sifter being wheelbarrow-mounted, it doesn't fit under the composter anymore.

The end result is great but I wanted to combine these two things and address the two biggest needs of any compost pile; heat and oxygen.  Common belief is that a regular compost pile (in a bin or on the ground) must be at least 3'x3'x3' to have enough volume to insulate it's core once it goes, shall we borrow a phrase from another industry, critical.  Once criticality is achieved the aerobic bacteria go to town on the bits in the core and are insulated by the surrounding mass to maintain their requisite heat.  Soon, the bacteria's resources deplete and the pile must be turned to introduce air and fresh organic matter to the core where the process can continue.  In a barrel composter, the heat is created by the absorption of sunlight and the contents of the barrel are processed more evenly, rather than just at the center.  This creates a problem though of the pile cooling during the night and also not being able to sustain itself during cold months.  Air is introduced by turning the barrel to churn its contents.  I've been using lengths of PVC pipe as paddles to help agitation, with holes drilled throughout to circulate air.  With this setup, I've gotten as little as two week turnaround on harvesting finished product.

I had questions though.  Why not have a big enough pile that can reach criticality based on volume alone but also give it means to heat via the sun to help it along during the winter?  Why not combine the sifter into the main design so to create a continuous-flow process, rather than running batches.  Can we also make the act of aerating the pile automated so the process isn't interrupted with a lack of human-involvement?

I kicked around some ideas and finally have a summer free so I can put my concepts to action, but I lack technical knowledge with things like metal fabrication and how well different materials can handle different weights and torque.  So, drawing inspiration from gardeners, wind turbines, the Chinese tire recycling industry, and Harbor Freight, I came up with this:


Uh, 3/4" PVC pipe at the top of the opening for scale.  Its main body is 4' diameter by 4' long and is turned by a vertical-axis turbine at the top, following some gear reduction (not pictured).  Please forgive the crappy drawing, I'm not great with the Sketchup.  I have one "gearbox" but may need another, one squirrel cage fan for the turbine (but maybe we could make a better one with the drums), and one ring-roller for forming flat-bar stock into circles, and zero clue where to go from here.

I know this is not the direction the thread was intended to go with the steel drums you have on hand but I wanted to expand on my comment in the previous thread and see if anyone is interested in collaborating on this.  I'd fancy some electronics incorporated into the design someday to maintain temperature, humidity, and log that data, along with wind speed and stuff, too.  Anyone up for a project?

- Jesse

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[Joseph Mckibben]

Sounds interesting Jesse. Come by an open hours sometime and we will discuss the project some more. I'm generally at Diode on Wednesday evenings.

[J.J.]

Some comments about some concerns -

1) On viability of steel drums - I have no idea how long they would last.  I have seen steel drum material, used as fire rings, last years.  But part of the idea behind the project is simply to give it a try and let nature run its course.  The drums are free, so there's a hurdle removed.

2) Regarding the original material housed in the drums as being a possible hazardous contaminant - as these are sealed drums I was thinking of cutting the main hatch into the interior, then building a roaring fire inside to burn off any material residue.  Cutting fluid is generally water and a soluble oil of some kind.  I'm not expecting anything that a good fire wouldn't reduce to something less onerous.  As it is, the one I plan to build for the Diode will be digesting grass clippings and other plant matter removed from around our building.  Technically, an industrial site.  I do not plan to grow any edibles, and would not recommend such on our soil at any rate.

Finally, I'm all for other ideas and builds and plans.  That's what The Diode is all about.  There is no need to pick the "one best way."  I of course will be willing to help others bring their creations to life.  That is also what The Diode is all about.

Due to my now busy work schedule Saturdays are at a premium, but I can meet before 12 noon.  Sundays are also at a premium, but at least I'm flexible on time.  I would enjoy getting together with others and hash out some ideas and start building!

[Jesse Collier]

Groovy, I got free time Wednesday so I can stop in.  Would anyone like me to bring by my existing barrel composter or trommel sifter to play with something tangible / see if the steel drums would fit in the frame?