Electrochemical decolourisation of cotton dye baths for reuse purposes: a way to reduce salinity of the textile wastewater

Electrochemical techniques offer many advantages for the treatment of industrial effluents. These processes are clean, operate at room temperature, and in most cases, do not need the addition of reagents (as in the case of reactive dyeing effluents). In particular, the electrochemical treatment of textile effluents is an efficient method to remove colour. In this work, diverse synthetic effluents containing reactive dyes were treated in an electrochemical cell with Ti/PtOx electrodes. The efficiency of the process to remove colour and the use of an additional UV irradiation were evaluated. Once the conditions were established in synthetic effluents, they were applied on two types of exhausted reactive dye baths collected from a cotton mill. Instead of the effluent discharge, another possibility is to reuse the decoloured effluents for a new dyeing process. In this sense, diverse experiments were carried out and conditions for the effluents reuse were established. The reuse of dyeing effluents implies an important reduction of the salt and water consumption as well as a reduction of the salinity of the discharged effluents.