A very simple, easy and fast way to remove silver out of spent fixer is to form any of a few insoluble silver compounds, such as silver sulfide. If you add sodium sulfide or liver of sulfur in exhausted fixer, you can easily see that silver sulfide is forming. There are other chemical agents that can precipitate insoluble silver compounds or metallic silver in the spent fixer bath. HOWEVER, the difficulty is that any of these methods will make particles smaller than 1 micron, and no inexpensive filtration method works to separate sludegs from a large quantity of treated solutions. (Most laboratory paper filters will let the particles go through, and the fine mesh filters will clog very fast.)To the best of my knowledge, all methods of silver recovery involve reducing the silver somehow (either electrolytically or chemically).