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

Abstract

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/PtO x 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.Postprint (published version

Removal of sodium salts and chemical oxygen demand from real reactive dye wastewater by the integrated process of chemical precipitation and extraction

“…In recent years the separation and recovery of reactive dyes from wastewater has given rise to a number of alternative methods [25,26]. Potential advantages are associated with liquid-liquid extraction methods, which include two types of operation: selective extraction or co-extraction and selective stripping [27,28].…”

“…Highly concentrated sodium salt in wastewater represents a form of pollution that is difficult to treat. Combining strategies of wastewater reuse and desalination technology makes it possible to convert wastewater into water of a suitable quality that can meet the standards required for various industrial applications [25,26,30]. Reverse osmosis and evaporation techniques, such as multi-stage flash, multi-effect evaporator, and reverse osmosis methods, are popular techniques used to desalinate contaminated waters [30,31].…”

Reducing the environmental impact of textile industry by reusing residual salts and water: ECUVal system

“…Although different class of dyes can be applied to dye cellulosic fibres, reactive dyes are the most common due to their high washing fastness values and great variability of colours [5,6]. The main drawback of reactive dyes is that, in order to ensure the fixation of the dye onto the fibre, the dyeing process must be carried out in alkaline medium and it also requires the addition of high amount of inorganic electrolyte, generally NaCl or Na 2 SO 4 [7][8][9]. The concentration of electrolyte varies between 0.6-0.8 kg salt/kg fibre, depending on the dye structure, shape and dyeing procedure [5,8].…”

Application of PVDF ultrafiltration membranes to treat and reuse textile wastewater

“…The reuse of textile wastewater is an important challenge since between 60 and 100 L of water are needed to produce a kilogram of textile product [21]. Other treatments such as photofenton [22], photocatalytic [23] and electrochemical [24] have been studied. These methods provided high colour removal but the generation of by-products and the high cost are their main limitations [25].…”