I had the same problem and if I got away with it would get dh to put the whole pot(I used yogurt pots)in the bin. Otherwise I would hold my nose as they stink and bin them. Also worth noting that if you go down the beer route you may get the whole neighbourhood slug population attracted to the brewery smell.I now have slug resistant plants only.
They will have drowned. The beer intoxicates them and they fall into the 'slug pub' You could dump them in the compost bin. I'm sure there are as many worms die as are born in mine! The other insect life and microbes will soon make short work of them.