Backyard Aquaponics
A place to discuss aquaponics

The grubs break down the scraps so well that the cleaning tends to be an annual thing. The grubs self harvest, meaning that they crawl out of the colony when they are fully grown as grubs. That is why there is an incline in the composter. Also the composter should not have that strong of a smell. If it does, you likely overloaded it. BSFL have the worlds most pathogen destroying stomach, but you know someone is going to cry foul if you fed the larva that fed on the manure to food that you are going to eat.

re: drainage

What if you made the sides separate to the base ?
So if you just sat the sides on top of a flat concrete slab, the imperfections in the 2 surfaces would be ample to drain away any liquid yet small enough to keep the BSFL in.

This is the side profile of what they had going at agriprotein. The shapes are constructed using angled curb stones used in road building simply laid out on their flat sides (side that faces the sidewalk) in lines with the spaces between and everything cemented up. This created the growing troughs and collection troughs and the crawl out ramps. Quite simple really. The ends where blocked on one side by the building wall and on the other side by a line of 90mm breeze blocks.

The guy said they had a more advanced idea which would involve raising the whole thing a bit and having a sluice type arrangement at the one end for sweeping out the larvae from the trough into a container to make it easier and quicker. They had a lot of larvae to sweep out!

oops... that drawing did not come out so well but you get the idea...

An interesting idea. It is kind of funny how much time is spent trying to keep concrete water tight, and the goal of this project it to not have it be. Then the next thing that comes to mind is does it even actually need a bottom? Has anyone tried a bottomless one? 100% containment of the larvae is not actually a good thing. We want some to get away so that they can mature.

Does anyone know the appropriate proportions to build based on family size and the amount of scraps said family would generate?

Something like this for a modular single unit mould. Its about 800mmx400mmx250 high

That is pretty sweet! I am afraid it might be a little more large scale than what I was thinking, but I see a lot of potential in that design too!

I wonder about the size too. It started out smaller but trying to maintain the right depth and the right angle it just grew. Main problem... its going to weigh a ton. Possibly literally.... I guess ferro cement could be sprayed in the mold and then chicken wire and more ferro cement...Then it would be lighter.

I am thinking of constructing a plug from lumber and board and whatever. Then take a mold from the plug using glass and resin. Then casting concrete into that. Once the mold is made they would be cheap to pop out.

The idea of the little sump is to be able to fill it with gravel as a filter... Not sure on that but it should work... Thoughts? Perhaps a stainless mesh can be cast into the mold somehow so it is integral to the casting....

Anyone,

Brian your design looks very interesting!

How deep should the "feed stock" depth be for the grubs to work on?

I'm wondering if one could stretch out that design into a long trough?

How much "feed stock" could be processed per linear foot of trough assuming there where enough grubs per linear foot of length?

ie "X" lbs (kilos) of grubs per linear foot would digest "Y" lbs. (kilos) amount of manure per day

Ideally, pie in the sky sorta thing, I would like to process about 100 lbs of horse manure per day.

Bob H

Indeed you could stretch it out as long as you want. The ideal depth according to the people at the agriprotein was "not deep at all" I did not get an actual depth figure but it looked like they where working on about a 4 inch to 6 inch depth. Their troughs where about 12 foot long and about 3 or 4 foot wide.

On the other questions I have no idea at all. From what I could see their targets where in the range of between 50 to 100Kg of mature grubs per day. They say on the website 2 tons a week but I doubt that was being achieved in reality. Not sure on the inputs at all. They where using manure and food scraps together as feed as well as some meat scraps. There where quite a lot of bones in the spent food material. The spent food looked like good fodder for earthworms to me.

I had a thought... perhaps the mold could be for a short concrete section that is open ended. Then you can lay out as many as you need and end them off with couple of breeze blocks or bricks.

Thanks Brian for the info. You guys have got my interest peaked now and I can't leave it alone

How did those guys remove the spent feed stock (pudding)?

My basement greenhouse will be 28 feet long and about 7 feet deep. Soooo why not put composting and a fish tank in the basement. Then put grow beds, DWC trough, NFT..... above that. BUT I HAVE TO consider some kind of flow thru design.

I'd like to see what you guys come up with using ferro cement in some way.

With that in mind I got looking at a blue barrel for starters. Get some data and then make your trough design the length of the green house basement. The big question in my mind is how will the resulting 'pudding" be handled.

Thinking of the bung hole in a blue barrel---will the resulting "pudding" flow or seep out that opening if the plug is taken out on occasion? Or would a small curved door be required?

Maybe someone with experience could comment on moving the "pudding "some how?

I think they just stopped feeding the trough in question and once it dried out and all the grubs crawled off they cleaned out that particular trough and started again. Perhaps if you have a long trough you just sluice of a section and let the grubs finish up there then clean it out and open up the gate again?

I have a through flow system but its not working that great as it is too deep. Also grubs migrate down and die. Its under 'Wheelie worm bin' It was a worm bin that got taken over by BSF.

I did a little more research into the type of concrete that I want to use. Pervious concrete is what I intend to use. It is mixed in such a way that water has no problems permeating it.

I am thinking that this would make a good base, then build the rest out of a more traditional concrete, ferrocement ,or what not material.

The next key would be to use a rather small aggregate. Perhaps even smaller than they use, mostly to keep the pores smaller than the BSFL would crawl through...