I have limited knowledge and ...
Published by Suhasini Bhatnagar, Employee at swaroop enterprises and biotech private limited.
I have limited knowledge and experience in the area yet felt can help so venturing in with a suggestion.
As far as I understand the colour is because you are using wood, essetially Lignin o why not digest lignin first using an appropriate enzyme.can suggest and demonstrate a natural source as well. The other problem is the issue of hevy metals in the effluent so even for that can suggest Bioremediation.