Continuous Flow/Flow Through Worm Composting

Comment by bpearcy10 on May 18, 2009 at 5:45pm

I've got a 96 gallon Toter trash can in the garage and after seeing another one one here that was made over the weekend, I've just got to make mine next weekend.

Comment by Jason on May 18, 2009 at 5:56pm

96 gallon - that's going to be a monster!

I'm looking forward to pictures...

Comment by Sue on May 23, 2009 at 6:03pm

Wow, seems like we have a competition going to build 55/96 gallon worm homes. I would like to build one too if I can get my hands on one of those bins for c-h-e-a-p.
Since I don't have one (yet), the following comment is based on MHO. If there is no grate at the bottom, then you will probably end up with a mucky wet mess of a vermicompost similar to the one from the Rubbermaid bins.

steamyb: you wrote "behind that door" which indicates the door will be closed. Meaning there will be no airflow from/to the bottom. True, you would have drilled holes all around and up and down, but moisture from the middle within the barrel will travel down. And by not having a grate there, any access liquid will collect at the bottom of the bin and make it mucky. With the grate, you can "scratch" at the entire bottom of the VC through the door to harvest, not just the area immidiately behind the door.

Comment by Jason on May 23, 2009 at 10:59pm

Usually when you see tips for bins, a big one is ensuring it's not too deep. having a container deeper than it is wide (like a barrel) isn't conducive to good worming because it means a lot of area with limited access to air. Even when I had an 18 gallon bin with no holes, the bottom was real mucky and slightly anaerobic. Even my 10 gallon bins with holes had this happen a bit. The only reason flow through designs get around this is the grating.

Also, I'm pretty sure harvesting through that door without any grating would be really, really hard and messy. If you don't want to scratch at poo, how about sticking your hand into a solid mass of it that goes up to your elbow? That's essentially what harvesting a system like that would require.

The whole not missing baby worms thing is also pretty covered by a flow through. That's the idea, at least.

Comment by Jason on May 24, 2009 at 9:46am

My comment about sticking your hand in poo was just pointing out that if you have one door in a barrel, in order to ever retrieve the compost at the opposite end from the door, you'd need to reach in and pull it out. You could get around this by putting in more doors at various places around the bin, I suppose. You'd still end up with a lot of mess.

One change I have thought about for the design of my bin (it would work with a barrel too, or any system except cloth-based ones) is having a sort of 'inner chamber' the same shape as the bin but about an inch smaller in all directions. This would sit on the grating and hold the bedding and food, and would be riddled with holes, thus ensuring maximum air exposure at all points of the system. You could also put PVC tubes throughout with holes if you wanted to make sure that not one part of the bin had a lack of oxygen. The hardest part of implementing this be far would be creating the chamber, and I doubt I'll ever do it for that reason, but I bet it would be effective.

I also have half designed a harvesting mechanism for my bin but didn't build it to cut down on time and money spent. If I ever have either one to spare I might go ahead and build it, though it still needs some polishing, design-wise. If it worked it would probably be pretty effective but you never know until you try. I also don't really mind using a garden fork to scratch things loose, at least not in principle.

There are a lot of barriers to 'easy' harvesting in a home-made flow through worm bin. The worm wigwam seems to have a pretty simple one (basically a crank that runs a bar or something along the bottom like any big flow through does) but that costs $600 and is huge. A small version of that would be pretty ideal if the price was right. Building a similar system into your own bin would require a lot of technical expertise and would still probably not work all that well.

I'll try to put some thought into various ways harvesting could be made easier.

Comment by Jason on May 24, 2009 at 11:33am

It's definitely not too much to ask but it will require some serious engineering I think.

I really like the idea of a pipe going down the middle of the bin that is connected to an agitator. The removable crank is a nice touch as well. Ideally, you would also have it connected to gears to lessen force you have to exert, but now we're getting into serious manufacturing. Get an appropriately sized electric motor and attach that to the top of the agitator, and you've got your 'auto-harvesting' bin.

Comment by Sue on May 24, 2009 at 12:09pm

A crank, especially a removable one, will that not squash and/or cut the worms? Or is that acceptable?
Just wondering.

I have a suspicion you guys have more fun in solving the problems/challenge of building a perfect bin than the composting.

Comment by Jason on May 24, 2009 at 3:48pm

Actually Sue, I don't have that much interest in building a 'perfect' bin. I'm really happy with the imperfect one I currently have, and the idea of taking the compost out with a garden fork doesn't bother me at all. For me it's all about the worms, and the end product.

But it is fun to imagine ways to improve things, even if I may never implement them...

Comment by Sue on May 24, 2009 at 7:55pm

steamb:
at the end of those 3 rods, do you have something like a "paddle" attached to it? If they are just rods with nothing else, then, when you turn it in a compact damp material, would it not just create 3 horizontal voids (from 3 rods at different hieights) with a height equal the diameter of the rod?

Another thing, if you place your barrel on a frame say made of 2 x 4 that has something like a drawer or tray underneath the barrel, you won't need to lift the barrel the way you had to if the barrel sits in a tub, to get the compost. You could line the drawer with tarp material to make it waterproof (if made of wood) or find something appropriate made of plastic.
Do you guys think this is practical?

Comment by catherine daly on May 25, 2009 at 5:45am

"I want a self contained, auto-harvesting flow-thru that can be harvested once a year (say in March) that will produce 1 or 2 wheel barrow fulls of worm-less, cocoon-less VC"
Steamy B you might be better to aim for year long harvesting and just store the compost until you need it.
A flow through works best once it is being harvested regularly from the bottom and fed at the top. That keeps the adult worms at the top, the cocoons are laid there, and should have hatched by the time you harvest from the bottom. (once you system is up and running harvestign every two or three feeds is good.)
If you leave the compost at the bottom without harvesting, it will compact and you lose the air flow. Also, as you go up the bin, doing a big harvest, you encounter more and more worms still working the compost because the air isn't reaching the area as well and decomposition is slower.
Have a look the the dirtmaker site to get an idea of the principles

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