Anybody who has done any kind of etching always eventually encounters the problem of what to do with all the spent solution. In electrolytic etching this is somewhat less of a problem because the solution isn't toxic or corrosive, but you still can't just pour it down the drain. I've recently discovered a simple trick that allows me to indefinitely re-use my saltwater solution. When I'm done with my etching, I simply filter the solution through a coffee filter. The filter catches most of the sludgy copper compound from the water and I'm left with nearly clear salt water, ready to use again and again. I've found that I just need to add more salt to the water now and then to freshen it up, because some of the salt bonds with the copper and comes out in the filtering process. Happy etching everyone!
***EDIT*** Since writing this post I have discovered that while you can re-use your solution for a long long time, it will eventually wear out. Once you start noticing your etching isn't as crisp as before, it's taking a lot longer or you're getting funky textures, replace the solution. Adding more salt will help extend the life but it will eventually be saturated with copper and won't take any more salt. What can I say, I'm learning as I go!
