I believe that there is (small-scale, lab. experiments) literature on the photocatalytic oxidation of dye wastes using TiO2.
Presumably the oxidation will remove the color, but I do not know to what extent it degrades the dye molecules.
I would guess that there is an apparatus to spray finely divided powders onto membranes; however, I'm unable to design a 50 Ktonnes/annum plant !!!
See: Kirk-Othmer Encyclopedia of Technology (multi-volume series) for reviews of topic.