The traditional silver reclaiming processes use steel wool. The soluble silver swaps with the iron in a chemical reaction and reduces to rusty water.
The issue with silver isn't as a "heavy metal" but in its antimicrobial properties. It will, or can at least, cause dead zones in waterways as a result of this. In sewer systems a common issue cited is runaway algae growth. Silver inhibits the growth of bacteria and other micro organisms, so the aluminum process (though i'm uncertain of its viability) would eliminate the issues associated with silver.
As a side note, does anyone know someway to sell the reclaimed silver? Most places I know only accept it if you're using their reclamation hardware.