I think if magnets have the right filter they could attract specific materials other than metal. like wool attracts hair, rice attracts water, I can't think of any other examples right now. Perhaps if you charge up an entire landfill with specific voltages and you get a properly filtered giant magnet, you might be able to pick out specific materials and recycle them. At the least if trash was reorganized into piles of the same material than they would bio degrade more naturally and become organic. There should also be a piping system where we channel all our bio waste into one area, like Texas.