you could add some fish to your water reclamation tank for a small aquaponics system. Grow a few plants to feed the fish and this forms a closed system. There is no need to fertilize, the fish do it for you! Permaculture at its finest!
Each time you crack an egg open, instead of tossing the shell into the trash, drop it into an open container that you keep in the fridge. When the container is full, crush the shells into small bits and sprinkle them around the base of your plants.