1.What are the chemicals could be used in treatment of effluent of garment/denim dyeing and processing plant?

We use powder sulpher dyes, direct dyes, reactive dyes to dye garments along with the other chemicals like Acetic acid, hydrogen peroxide, sodium sulphide, softening agent etc; now what are the chemical could be used at ETP for flocculants & coagulant. We use lime water, sodium hypochlorite, ferrus alum to treat the effluent. Is there any better chemical or methods?

2. Pollution control board marked sludge coming from ETP as hazardous. What are the basis of doing so?

A query asking about method used to  to determine the sludge of ETP as hazardous was asked to West Bengal Pollution Control Board. They show me the law of hazardous chemicals where it has mentioned that any dyes and intermediaries would fall under hazardous waste management.

How all the dyes could be marked as hazardous. B) There must be norms to mark some chemicals as hazardous. if the question of the question 'B)' is yes then what are that criteria?

Amitabh Mukherjee
dt.co@sify.com