I just dump my stop bath, but I collect the fixer and take it to the the "Household Hazardous Waste" collection center in Columbus. The silver in the fixer is not good for the environment. I've heard that it's not really an issue in the quantities that amateurs use, but I take mine in anyway. Fixer and selenium toner. I have known some folks to extract the silver from their used fixer. It can be sold, but I don't know who buys it.