I normally put food waste and grass cuttings in my brown bin.
Can I put ash in it??
Like, for example does anyone put ash in their compost bin??
It all depends!
Ash from wood burning only is a very good additive for compost. However coal ash or ash from burning other materials is not as this type of ash will most likely contain elements which are harmful to soil and/or plants.
Unadulterated wood ash contains many valuable elements making it a valauble and ideal compost supplement which I would keep and use.
I put it in the compost bin i think it helps break the rest down