Reuse of textile wastewater after homogenization–decantation treatment coupled to PVDF ultrafiltration membranes

The textile industry is one of the largest consumers of water in the world and its wastewater is a serious problem when it is discharged without the proper treatment. In this work, wastewater generated by textile industry was treated coupling a homogenization–decantation treatment with polyvinylidene difluoride (PVDF) ultrafiltration membranes. Initially, the wastewater was aerated in a homogenization–decantation tank where 17% colour and 10% chemical oxygen demand (COD) were removed. The aerated effluent was treated with an ultrafiltration membrane in order to reuse the permeate in new dyeing processes. Firstly, the ultrafiltration treatment was performed in a laboratory plant. The permeate analysis showed 20% colour removal and 60% COD decrease. On the basis of these results, a semi-industrial system was built. With this plant, the permeate characterization showed similar results. The system was found to be scalable and suitable for the treatment of this kind of effluents. Finally, new dyeings were performed with both permeates. Monochromatic dyeings were carried out with 100% permeate whereas 50% permeate was reused for dyeings with a mixture of three dyes. The colour differences were found to be lower than 1.5, which was the acceptance value establishedPostprint (author's final draft

Étiquettes écologiques pour les matières textiles. Dosage de métaux lourds

En este trabajo se realiza una breve descripción de las diferentes etiquetas ecológicas, centrándose en este caso en la dos ecoetiquetas textiles más importantes: EU Eco-label y Öeko Tex estándar 100. Existe una tercera ecoetiqueta textil utilizada únicamente en alfombras: GuT Eco-label. Para la obtención de las ecoetiquetas se tienen en cuenta diferentes parámetros. Uno de los parámetros considerados en las etiquetas ecológicas textiles es la presencia de metales pesados en los tejidos, tanto en el producto acabado, como en su proceso de fabricación. Es por ello, que cada una de las ecoetiquetas textiles fija unos valores límites específicos. La determinación de estos metales se realiza generalmente mediante espectrofotometría de absorción atómica, siguiendo dos técnicas diferentes de atomización de los metales. La selección de una u otra técnica se basa principalmente en la concentración de metales a determinar o en el valor límite establecido por la ecoetiqueta. Otra técnica rápida y sensible empleada para la determinación de metales es la espectrofotometría de emisión óptica de plasma acoplado inductivamenteIn this work a brief description of the different ecological labels is carried out, focusing on the two more important textile eco-labels: EU Ecolabel and Öeko Tex standard 100. There is a third textile eco-label used only in carpets: GuT Ecolabel. For the obtaining of the eco-labels, different parameters are taken into account. One of the parameters considered in the textile ecological labels is the presence of heavy metals in the fabrics, in the finished product, as well as in their manufacturing process. For this reason, each of the textile eco-labels fixes some specific limit values. The determination of these metals is carried out generally through atomic absorption spectrophotometry, following two different metal atomization techniques. The selection of one of these techniques is based on the metal concentration to analyse or on the value limit established by the eco-label. Another fast and sensitive technique used for the determination of metals is the inductively coupled plasma-optical emission spectrophotometry.Dans ce travail on réalise une brève description des différentes étiquettes écologiques, les eco-étiquettes textiles les plus importantes sont: EU Éco-label et Öeko Tex standard 100. Il y a une troisième eco-étiquette textile employée uniquement pour les tapis: GuT Eco-label. Pour l'obtention des eco-étiquettes, différents paramètres sont évalués. Un des paramètres considérés dans les étiquettes écologiques textiles est la présence de métaux lourds dans les tissus, tant dans les produits finis, comme pendent leur processus de fabrication. Pour cette raison chacune des eco-étiquettes textiles a établit des valeurs limites spécifiques. Le dosage de ces métaux se réalise généralement par spectrophotométrie d’absorption atomique, en suivant deux techniques différentes d'atomisation des métaux. La sélection d'une ou de l’autre technique est basée principalement sur la concentration de métaux à doser ou sur la valeur limite établie par l'eco-étiquette. Une autre technique rapide et sensible employée pour le dosage de métaux est la spectrophotométrie d'émission optique à plasma couplage inductifPeer Reviewe

Kinetic models for the electrochemical decolouration of two reactive azo dyes

In this work, the indirect oxidation of two azo dyes (Colour Index Reactive Orange 4 and 13) was performed in an electrochemical batch cell in the presence of chloride as an electrolyte. The effect of different operational parameters on the electrochemical treatment was tested. Kinetic plots consisting of two linear portions were obtained in some experiments. The rate constants and the breaking point between the two linear portions were modelled to evaluate the influence of dye concentration, conductivity and pH. Good correlation between the experimental and the modelled constants and breaking points was observed. Models showed that the dye concentration is the most significant factor in the electrochemical treatment of both dyes, although conductivity and pH were also significant either individually or in interaction with other factors.Peer ReviewedPostprint (author's final draft

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

The textile industry is one of the largest consumers of water in the world and its wastewater constitutes a serious problem when it is discharged without the proper treatment. Different techniques are being applied for treating textile effluents. But, as far as we know, none of them consider the reuse of the clarified effluents. In this work, a recently developed wastewater system named ECUVal is proposed to treat and subsequently reuse the effluents generated by the dyeing process of a textile mill, which usually have high dyes and salt content. With this system, a reduction of water and salt consumption is achieved and simultaneously the volume of discharged effluents is also reduced. The ECUVal system is based on an electrochemical treatment assisted by UV irradiation. The system is able to remove colour completely. Colour removal efficiencies between 64 and 99% were obtained depending on the intensity applied. Moreover, the treated effluents are reconstituted in the system to be reused in new dyeing processes. Thus, 70% of water and up to 72% of salt reuse was achieved. The chromatic coordinates of fabrics dyed with the treated effluent were evaluated with respect to reference ones. Dyeings performed with reused effluents were in general into the acceptance limit of the textile industry (DECMC(2:1)¿=¿1). Finally, the environmental impact of the wastewater treatment currently performed in the textile companies was compared with respect to the ECUVal treatment by means of life cycle assessment. It was concluded that the use of the system reduces significantly the environmental impact of the textile industry.Peer ReviewedPostprint (author's final draft

Modelling for the efficient effluent dye removal to reuse water and salt

The objective of this work was to determine the optimal conditions for the electrooxidation treatment in order to decolourise the effluents that contain reactive dyes. According to the results, when Na2SO4 is used as an electrolyte, the decolouration reactions follow first-order kinetics. However, when NaCl is present in the effluent, the first-order kinetics is stabilised after applying a minimal electric current value. The models obtained from the results show that the higher the concentration of NaCl, the lower the energy consumption. On the other hand, an increase in dye concentration leads to an increase in electrical consumption. In relation to the pH, the results show that it is not a key factor in the decolouration efficiency. Finally, the obtained model was applied to two real effluents. The feasibility of individually treating the effluents from the dyeing process and those from the subsequent wash-off process was evaluated. From an industrial application point of view, it is recommended to mix both effluents before treatment, especially when the dye concentration is highPostprint (published version

ECUval project: a feasible system to recover salts and reduce water consumption in textile industry

ECUVal system is based on the in situ degradation of organic compounds contained in saline effluents. ECUVal achieves the partial or total degradation of organic compounds by means of an electrochemical treatment combined with ultraviolet irradiation. The removal of organic matter is carried out only by means of electricity, without the addition of chemical reagents because the salts contained in the effluents are used as an electrolyte. After the electrochemical+UV treatment, the effluent still contains all the initial salts and it can be reused in a new production process. Thus, ECUVal process enables to reduce both water and salt consumption, with the subsequent economical and environmental benefits: saving of raw materials and process water, diminution of wastewater salinity and reduction of wastewater discharge taxes. ECUVal system can be applied to remove organic compounds from any type of industrial wastewater with a high content of salts. The use of ECUVal process to treat textile wastewater is especially interesting because dyeing and washing effluents contain chemical additives and residual dyes, which cannot be easily degraded. In general, treatments based on biological processes are inefficient to remove dyes due to their low biodegradability. Physicochemical treatments such as coagulation-flocculation or membrane filtration are used with this purpose but these treatments generate a waste that requires a further treatment. In this sense, the main advantages of the ECUVal system are that no residues are generated and no chemicals are should be added. In addition, the reuse process allows saving 70-100% dyeing water and 15-60% dyeing electrolyte

Hydroponic System: A Promising Biotechnology for Food Production and Wastewater Treatment

Several regions of the world are suffering from water scarcity and available water pollution. Mediterranean countries (such as Portugal, Spain, Italy, Greece, Tunisia, Israel, and Jordan) do not meet the requirements in terms of quantity that have been increasing in the last decades for the various sectors, due to lack of water resources, winters with low rainfalls, and summers with hot and dry conditions. Agriculture is the leading water-consuming sector (70%–80%), followed by industry and domestic use. However, industrial and domestic uses are considered priorities, conditioning the amount of accessible water for the agriculture sector. the use of reclaimed water should be considered in the integrated water management system to avoid damages to the environment (surface and underground water, soil, fauna, and flora) and public health. The use of wastewater for irrigation should be carefully investigated and planned in terms of proper treatment, treated wastewater quality, volume of treated wastewater used, application method, physicochemical characterization of soil, nutritional needs of plants, distance to existing water sources, risk of animal and human contamination, and others. Environmental and economic gains can be achieved by reusing wastewater if the study, planning, and application are performed in a sustainable basis.info:eu-repo/semantics/publishedVersio

Combining electrochemistry and UV for the simultaneous wastewater decolorization and reduction of salinity

Textile dyeing processes with reactive dyes consume high amount of water and generate wastewater containing residual dyes and salts. In this work, wastewater generated by a textile industry was treated by means of electrochemical techniques combined with ultraviolet irradiation. Five industrial wastewaters were collected in a textile mill and were treated at 10 A in an electrochemical cell. Full color removal was obtained after 10 minutes of treatment. The optimization of the electrochemical treatment was performed in order to select the most suitable conditions. Subsequently the decolorized effluents, which still contain salts, were irradiated with UV light to remove residual oxidants and were reconstituted for its reuse. This procedure enabled to reuse 70% water and 64% salt in the dyeing process. The chromatic coordinates of these dyed samples were evaluated with respect to reference ones. In all cases, samples dyed with the reused effluents showed colour differences into acceptance limit of the textile industry (DECMC(2:1) values lower than 1)