Let's get a little perspective on silver recovery. Check out Kodak Publication J-210 "Sources of Silver in Photographic Processing Facilities". It provides an example of how much silver can be recovered by a lab. A lab processing 50 rolls per day, 6 days per week, i.e., 15,000 rolls per year can recover 280 troy oz. of silver per year. At $20 per oz. you could get $5,600 per year for that amount of silver, not including the cost of equipment and chemicals to recover it. But that's for a lab. I typically shoot and develop 60 rolls of film per year. So, proportionally, I could get $22 a year for the silver, not including the cost of recovering it. In other words, it's not worth considering. On the environmental side, the amount (mass) of silver you dispose to the drain is so small that it's probably not detectable after dilution, perticularly if you are on a community sewer and sewage treatment plant system. Maybe a heavy home film/paper developer on a septic system would have a concern after many years.