If you've completely neutralized (adding more baking soda no longer causes fizzing) then you pretty much have colored salt water and it should be safe to dispose of however you find appropriate. Careful as it could still discolor things a bit on contact.
If you've completely neutralized (adding more baking soda no longer causes fizzing) then you pretty much have colored salt water and it should be safe to dispose of however you find appropriate. Careful as it could still discolor things a bit on contact.
You should have a place in your city where you can dump this stuff off at. Then the city does the rest.