Thanks guys. I am asking not because of the cost, but frequency / inconvenience of disposing used chemicals.
If you want the absolute lowest chemical waste, not to mention lowest chemical cost per roll, nothing can compete with a replenished system that uses squeegees at the end of every tank. (Self-feeding roller-transport machines, like minilab processors get a squeegee effect from passing the film between opposing rollers). The significance of squeegees is that they greatly reduce carryover, due to wet film, into the following chemical tanks. (Since carryover dilutes the following tank this means that a higher replenishment rate is needed to compensate for a lack of squeegees.)
Obviously you are not gonna be using squeegees in a hand processing setup, but replenishment ought to be possible, provided that you are not using something like a Jobo processor (Kodak recommends single-use, only, for such machines.)
You would ideally use the LORR replenisher, as that has the lowest replenishment rate, something like 25 ml per roll (135-36, or 120 roll-film). You would also want a multi-stage fixer system as this can significantly reduce fixer use. (The limit on fixer use is generally seen as when the silver concentration exceeds some predetermined aim. If you use a two stage system you'll end up with a significantly lower silver concentration in the second tank, meaning that more film can be processed before reaching the limit.)
Anyway, these are the ways to minimize waste. But all things considered, this might be even more inconvenient than dealing with the waste.
If you don't do commercial processing, where you need a sewering permit, and you are on a municipal sewer, there is a good likelihood that you can just put it all down the drain. You'd have to check the local laws. But the photo chemicals are relatively benign, even the photographic silver, and a municipal sewer system should easily be able to handle it. But in the spirit of conserving silver you might consider using a silver recovery device such as the "Silver Magnet," a small, low current electroplating system. (One of the members here, John Nanian, is a dealer for them.) You'd have to process a pretty healthy amount of film to collect enough silver to pay for a Silver Magnet, but at least it's all in one place as metallic silver. If you go to a hazardous waste disposal outfit it's more than likely incinerated with the ash going into a landfill. So ... you gotta decide for yourself (after reviewing local laws, of course).
