The European textile industry is in a leading position in terms of quality, design, creativity and fashion, despite numerous relocations over the last 15 years. One of its main drivers of growth is in eco-innovation and eco-designing. Considering that 600 million m3 of fresh water are consumed in Europe by the textile finishing industry ( scouring, printing and dyeing), reducing the water consumption and the related polluted effluent discharges represents a huge eco-challenge.
Nowadays, the most widespread technology for destroying ordinary organic pollutants in textile wastewater consists of bio separating devices, which are not efficient enough for achieving a complete decolourization. The most important parameter for obtaining a relevant textile water and wastewater treatment achievement for water recycling is the complete decolourization of the wastewater. Although the combination of both a precipitation, which removes a huge part of present dyes, and a biological treatment, separates the majority of pollutants, decolourization is not sufficient in the end. An additional advanced oxidation process (AOP) is then needed for eliminating residual tiny dyes.
In this context, the TEXAFLOK flocculating agent has been developed by Inotex (from Czech Republic) to decolourize the textile wastewater that contains anion active dyes. This chemical separating technology is performed within a global water treatment process, before both a biological treatment and an advanced oxidation process (or AOP) take place. This approach is an innovative tailored-made train concept treatment.
To overcome this barrier, an innovative flocculating reactant has been developed. This agent is a highly viscous liquid which contains cationic species. To be easily dosed, it is recommended to dilute it before using. When applied, the flocculating agent is capable of reacting with a wide range of soluble dyes to create insoluble compounds which can then be removed easily. When insoluble dyes are present they co-precipitate too. The sludge amount that is produced is low (it is equivalent to the amount of organic dyes present) and can be discharged directly into the biological step of wastewater treatment plant without any further separating device. The coloured sludge is subsequently destroyed during the further anaerobic digesting step of the surplus sludge.
Several laboratory-scale analyses were conducted and have shown that the decolourization of the waste water containing reactive dyes using the combined treatment technology (i.e. flocculation, biological treatment and oxidation treatment) was very efficient. The water that is treated reaches the general quality standards of textile process for reuse. This sustainable water cycle achievement is confirmed by reusing the treated water in various finishing technologies (such as pre-treatment and dyeing of different textile fibres) without negative influence on final textile quality.
Moreover, it has been shown that the dosage of the flocculating agent is of paramount importance to obtain a proper decolourization. This flocculating step is the first to be applied within an integrated treatment approach. It is followed by a biological treatment and an advanced oxidation process (H2O2/UV; similar effects can be achieved with ozone/AOP too) which breaks down the rest of organic persistent substances.
The flocculent can be used in textile waste water treatment processes but also in other cases where decolourization is targeted. As matters stand, transferring this technology to other industrial sectors is conceivable but requires further development. Therefore, the technology readiness level of this technology is estimated to be 7 on the TRL scale.