I learned about vermiculture backwards. I visited a coffee processing plant in Palmichal, near Tabarcia, in Costa Rica, and witnessed a large industrial vermiculture operation. They were composting their waste coffee hulls with more redworms than I even imagined could exist. They were using a windrowing system that is now the standard of the industry. They had learned most of what they were doing from a scientist from Pinar del Rio, in Cuba. I hope you have time to watch the slide show. My aroused curiousity started a search that seemed to always end up at very large or very small systems. There seems to be a need for a medium-sized system. You can't go wrong by reading the book "Worms Eat My Garbage", by the late Mary Appelhof, if you want a small system. I bought my first pound of Eisenia fetida from her.
A VermiChester system is a simple arrangement of stackable bakery trays on a raised base. The trays are completely filled with composting worms and screened composted organic waste.
Water is added until the system drips dissolved worm castings into a pail. The drippings are siphoned to remove large sediment, bottled and labeled VermiJuice for sale at Farmer's Markets, etc. Scroll down for a post about "Compost Tea" The liquid can be diluted as much as 8 times for plant feeding and irrigation. Some users have seen a reduction in plant pests as well as increased growth of healthy plants.
Rotation of the trays allows the bottom tray to be removed for harvesting, and stirring of the contents during the rotation loosens the contents to ensure full trays and more even access by the worms. The percolation of the castings exposes the slower decomposing materials to a longer period of digestion. In time, the contents become VermiCompost which is harvested and placed in plastic trash bags inside of double-thick paper bags of about 10 pounds each for garden and greenhouse purposes.
While it would appear that the purpose is to restore humus to depleted soils, the big picture involves eliminating organic waste from landfills, etc. The really big picture has to do with processing the spent effluent from methane generation, but that is another story.
In Costa Rica, small farmers with 6, or more, pigs, collect the manure in a modified septic tank with a plastic "bladder" cover. The manure produces methane which is piped into the kitchen for cooking. The digester drains out of the bottom. Vermicomposting the spent effluent would increase the value at least 8 times. The potential application for CAFOs in the USA should be obvious. That would require a much larger system.