A new micro-brewery is opening near me and they are looking for an outlet to dispose of their spent grains. Like the amount would be around 350 ponds per week. I only raise a couple of cows, about 10 goats, 15 laying hens, and 2 pet PBP's so that's more than I can use. But I was wondering about using the spent grains in a vermiculture operation, with casting and compost being the desirable products. I welcome any experience-based feedback.
I don't know about vermiculture, but historically speaking, 'cakes' made of spent industrially used crops were quite popular as a fertiliser. They could be spread on the field without any additional processing (particularly associated with cereals), or first soaked in liquid manure or nightsoil (commonly done for a flax crop). So there might not even be a need to vermicompost first, depending on what you're growing and whether you're collecting your animals' liquid excretions.
Depending on where you have your bins, you might have pest issues with that volume of grain.
There is now at least one commercialised home biogas generator featuring inflating bladders that hold the waste and use a water process to create the anaerobic environment that methanogenic bacteria prefer. I don't know what the quality of the liquid fertiliser that comes out of the process is, and in fact, I really hope I get to ask Redhawk about it soon, but it could produce significant amounts of biogas, with the amounts you're discussing. It wouldn't be my first choice, but you are talking about a lot of spent grain.
I think that worms are an excellent idea, if pests aren't an overwhelming issue, but I don't think that they are the only option. You could look into seeing if anyone is using spent brewers' grains to feed crickets, either for the reptile feed market, or for the entomophagy market. In terms of converting the spent grains into a foodsource for chickens with a higher protein content than just the spent grain, black soldier fly larvae and mealworms are also options.
You could find yourself making high-protein insect-based feed for chickens and fish, just freezing all your animals don't eat and finding some operations local to you that might buy from you, especially if they like the idea of upcycling a waste product as a sales angle.
Likewise, you could just see if there are any other small-scale operators that can't take the quantities you can, but would be glad for a little spent grain to supplement their own animals. You never know what you could get for it, even bartering for their goods, unless you give it a shot.
Incidentally, your worms would probably love it if you could source some spent coffee grounds as well. If you mixed them half and half with the spent grains and used the resultant mix as an amendment in the soil, I am fairly certain that the soil life would simply explode on you.
There are a number of ways you could use those grains. You could be looking at a number of potential income streams, if you can find the buyers.
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein
I like the idea of baking it into hardtack in a wood or solaroven.
Bread for livestock was a thing.
Baked into cakes, they would keep,and could be packaged and sold.
If you feed your livestock out in the feild, composting might take care of itself,with spilled food being scratched trampled and otherwise tilled into the soil.
Those pet pigs might enjoy rooting for grain,prepping garden beds in the process.
Don't forget that you can add those brewer grains to your compost heaps, what is cool about doing that is the yeast organisms love the stuff as do most bacteria so you can have a really bio rich compost easily with just the leftovers from feeding your animals.