Did you do any recovery of silver from wash water?
Hi, yes, at one time we (the large chain outfit where I spent a lot of years) did silver recovery from wash water. And in fact, I personally oversaw the purchase, installation, and operation. I should probably say a little about myself, which I have typically avoided online. I started out as fundamentally a photographer, but at some point took a "temporary" excursion into lab work when color still seemed a sort of black art. I figured to stick with it as long as I was learning new things, which kept going on, and I eventually found the tech work more interesting and challenging than actually shooting. Being that it was a very large outfit, but, shall I say, frugal, I was able to get involved, and gain deep experience in many areas, with tremendous technical support from all the major photo manufacturers.
I spent a number of years as the Quality Control Dept manager, including the time period when US effluent regulations became stringent. My department handled those things, and I personally worked out a lot of the basic silver control strategies and system designs.
Anyway, our wash water system was custom built by CPAC, in NY state, based on research published by Rami Mina (as I recall) of Kodak. It used a couple of ion-exchange columns (Rohm & Haas IRA 400, I think) to "collect" silver, which was later stripped off by the "mass action" of a thiosulfate solution - essentially "fixer," which was run through an electrolytic silver recovery unit. In the meantime, a "reconditioning" bath was pumped through the columns, and they were returned to service.
Ultimately the system was not very successful. When the resin was fresh it worked really well, and we could easily meet the regulatory limits, which were something like 2/10 mg silver per liter. But on multiple stripping and reconditioning cycles, the resin gradually lost capacity and began to "leak" higher concentrations of silver. Mina's original research was necessarily done on a smaller (bench?) scale, whereas our system ran 50 gal/min; things like resin life didn't scale up well in the real world.
Eventually we changed our strategy to rely mainly on carefully "tuned" multi-stage fix or blix with countercurrent replenishment flow. The idea was to keep the "main" wash water from ever reaching the regulatory limits, and the solutions that had to be desilvered could use less-sophisticated technology. There was more to it than I've said, but it was very successful for many years, easily and reliably meeting the effluent limits.
When I make suggestions in these areas, they're usually based on my practical experience and understanding. You might note that I tend to put in conditions, like "if your effluent is regulated," to be clear what I am recommending. From a strictly financial viewpoint (ignoring fines) it's almost never worth going after low concentration silver. This is generally done only to meet regulatory limits.
) and guess what? None of them have a single sign of any fading or staining on them at all. So, whenever I see posts like this, discussing the benefits of a two bath over a one bath etc., I sit back and relax whilst my prints soak in their water bath, with the only real difference being that they get their rinsing done in a slot washer rather than the bath itself, knowing that they will be fine for future viewing. 
