yes you can, will work fine, especially pre-composted to get past the hot stage - any decaying organic material is potential worm food, no matter how it's been treated

Bill

Thank you so much. I mixed some of it with kitchen waste, just to improve things a bit

I use my DH's brewing waste in my compost bin, not my worm bin. A small amount really heats up the compost pile, even a large one, so be really careful of that if you put it in your worm bin. I once killed a whole bin of worms by letting it heat up too much and I am sure you don't want to do that. They are also really wet and I would not put anything that wet in my worm bin. Whatever you do, don't put a whole bucket of them in your worn bin all at once.

You could probably use them in your worm bin, but be really careful.

I've actually divided the grains into two, mixed each with kitchen waste and they are now busy composting the conventional way. I'll keep them this way for about a month to 6 weeks, mainly for it to pass the hot stage of composting. The thinking is also that this way, there will be a tremendous increase in the microbial population, which I understand would serve as food for the worms, as well as breaking down organic matter. I'm also mindful not too keep the stage of conventional composting for too long, since from what I've read I understand that this will impact the nutrient quality of the worm casting negatively.

Update!! I started feeding the worms in the can-o-worms with the pre-composted spent grains/ kitchen waste mix. They seem to be quite happy. I now also add tissue paper to the mix. It helps to control the level of moisture, and the worms are definitely not complaining!!