Reclamation and reuse of process water from reactive dyeing of cotton

This paper presents Danish experiences with water reclamation and reuse in the reactive dyeing of cotton. Experiences include development of new dyeing and rinsing recipes and of water reclamation techniques leading to large savings in time, water, energy, and chemicals. Investigated water reclamation techniques are chemical precipitation, membrane filtration, activated carbon adsorption, and counter current evaporation/condensation. The advantages and limitations of each technique have been identified in lab-scale and documented in pilot-scale, An overall solution has been chosen based on membrane technology for the rinse water and activated carbon adsorption for the dye bath itself. The solution implies hot water reuse in rinsing, reuse of filtration remanence in anaerobic digesters, and reuse of dye bath water and salts. This solution is under implementation as a small demonstration plant at a Danish cotton dyehouse.