Take Rodinal or HC-110 as the developer, and a rapid fixer, and some plain old steel wool. Developer goes down the drain one shot, and spent fixer once exhausted into a bucket for a few days with steel wool. Carefully decant the supernatant of fixer bucket, including not expired fixer the second last day, and wipe up the silver sludge in the bottom the last day with a couple of paper towels, and zip lock them up and fly home with them where you can decommision them safely. The supernatant can go down the drain with a flush of water.