on the cathode it is 99% silver flake (from what i understand),
so you can ... you can hoard it, sell it to jewelers, or do whatever you want with it ...
i know of some folks that just save it, and when the spot price of silver climbs, they send it to be refined ..
the refiners that are "lined up" to help with the magnet, don't charge minimums &c so there are no
extra costs, you can have it refined locally if you want ( or find a waste hauler to take it ) but i don't know
what sort of payment they will offer ...
the trickle tanks ... i think there is more than just silver flake on
the bits of steel wool/iron &c, but i am not really sure ...