When bottling your beer, you'll notice that once you get to the level around the tap, there is a layer of residue at the base of the fermenter with a cloudy liquid layer above it. If you look closely at this picture you can see the residue layer - it's the lighter layer below tap level at the base of the fermenter.
You don't want to bottle this residue so when you reach the cloudy liquid level just above it the bottling process is complete. But just because you don't bottle the residue doesn't mean it's entirely a waste product. It works a treat in the garden as snail and slug bait. You've probably heard of using beer to catch snails - well this stuff is beer plus other brewing residue and we've found it works even better.
We pour the residue from the fermenter into an empty juice bottle to store it and then use it as needed. Cut off the bottom of soft drink bottles to make a saucer and you are set. In the picture below we have used the lid from the can in the beer kit. Place saucers of the residue around your vegie garden where snails and slugs are a problem.
The slugs and snails go crazy for the stuff, crawl in and drown. You'll be surprised to see how well it works!
By the way, the plants in the picture above are mostly volunteer plants. The exception is the onion which sprouted in our cupboard ....so we planted it. The endive on the left was a volunteer in a friend's garden, and the oakleaf lettuce and potato were all volunteers in our garden. It's the direct benefit of letting some things go to seed - our bountiful lettuce crop this year has been all from volunteer plants.