Charcoal + salt + vinegar can be used as detergent/softener. It completely eliminates the chemical input into laundry system.
I have a friend of mine who uses them for washihg cloths, and she sees no disadvantages in using charcoal compared to using conventional chemical detergents.
I'd like to try.......but I would guess it won't work with "black charcoal". The kind of charcoal that the people in Japan usually use for laundry is called Bincho-tan or white charcoal. High-quality Bincho-tan is steamed at high temperatures therefore pretty solid and hard.
So, even soaked in washing machine, it doesn't crumble. It can be repeatedly used for about three months.
When planting trees become strategical tool to sequester CO2, strategical method to manage/control forest would be needed ever than before.
Producing charcoal detergent from those forests would be one way to close the loop.
(caviat: high quality white charcoal can only be produced from specific kind of trees...)