Dyeing of cotton with reactive dyestuffs: the continuous reuse of textile wastewater effluent treated by Ultraviolet / Hydrogen peroxide homogeneous photocatalysis

Ten differents dyeings were made using reuse water obtained from effluent after treatment by homogeneous photocatalysis. Before and after the UV/H2O2 treatments, the concentration of sodium chloride (NaCl), the absorbance (Abs) and the amount of total organic carbon (TOC) were monitored. All rates of decolorization were above 92% and the removal of TOC was above 88% in all treatments. Compared with the same dyeings made with deionized water, the total deviation (ΔE*) between the colors did not exceed 1.05. Currently, for a monthly production of 20 dyeings of 100 kg each, 160 m3 of water is consumed and an equal volume of effluent is generated. The same dyeings made by the process proposed in this study, with an addition of 10 m3 of water after 20 dyeings, would consume just 60 m3 of water, without effluent discharge containing high amounts of organic matter and high values of absorbance.