Vermicomposting is using small worm bins containing worms that eat garbage. "Worms eat my garbage", by Mary Appelhof, was first published in 1982, from scholarly work she did in Wales in 1973. It was republished in 1997.
I say, between 73 and 97, she should have scaled up. After all, for hundreds of years, "Pigs eat my garbage" has been the standard in Cairo (daytime population 27M). For places like Tokyo and Mexico City and Beijing, we need more than worms.
"Velociraptors eat my carrion" would be going too far, I think. But for a major city, like New York or Chicago, "Rats eat my garbage", or "dung beetles" at least, would be more appropriate technology.
The "NIMBY" (Not In My BackYard) potential for a contained rat digester is high, so you'd need to build this with a lot of redundant security. I'm thinking something much more modest than Boston's "Big Dig", but probably higher scale than a paper mill hydropulper.
Think of a giant cast iron pit, as deep as the pit Luke Skywalker is thrown down chez Jabba the Hutt. The pit would have tunnels that could be cut off or opened from a central control room (like Jabba's, but smaller), and the tunnels would lead to little rat nests. You could choose how many tunnels to open from the central control room. You may want to have a giant blade, a whirly disposal-all blender, at the bottom of the pit.
Trucks would back up to the pit, loaded with wet garbage. They'd dump the loads into it while the tunnels were closed. Then the cage gate would close up, and the rats would be released onto the pile. After they'd eaten their fill, the smart ones would retire to their tunnels. Any stragglers would get cleaned up by the disposal-all and be there for the next tunnel opening.
From time to time, for population control, you'd have to flood the rat chambers.
I can think of no reason why this would not work. I'll work on a diagram. Maybe I can convince my wife to let me build a smaller scale model, using dung beetles.