Unfortunately, the answer ...

Unfortunately, the answer depends on the level of color, types of colorants, and the effluent permit requirements. Even with textile colorants, there are several answers depending on the chemical family of the dyes and/or pigments.

The usual systems to test are oxidants (ozone, peroxide), coagulation, anoxic treatment, carbon, and filtration (low MWCO UF, NF, RO). Usually, that is the order when considering cost. Chlorine was the best for many years, but chlorine is basically not allowed in most locations.

For diverse and large systems, you may require a combination. Some textile facilities use anoxic, ozone, and coagulation to meet very strict permit limits.

If you have more data, you could get better answers.