Figure 1: Position EColoRO concept for closed-loop wastewater treatment in the textile industry
In the dyeing and printing processes of the textile industry considerable amounts of water are consumed. The top right corner of figure 1 depicts how water is taken in from fresh water sources. Usually a buffering station is in place to manage fluctuations in water availability. Fresh water is then used in the various unit processes. The out coming wastewater usually contains a mix of colorants, chemicals, salts, metals and other organic and inorganic compounds. Due to large fluctuations in composition often also a buffering station is placed at the wastewater discharge outlet. Effluent then is sometimes treated by the manufacturer. In other instances it is supplied to municipal wastewater utilities or it is discharged straight into the environment.
The EColoRO concept
The ECWRTI project aims to bring a new technological concept to the market that closes the waterloop by separating the water, organometallics and salty brine and creating a produced clean water that can be fully re-used.
Figure 2: The EColoRO concept integrated in a textile plant
Figure 2 gives a schedule of the EColoRO process and concept. The wastewater effluent is first treated by electro coagulation. Fe3+ ions are released from an iron source through electrolytic action from low voltage DC. The formed Fe3+ is directly coagulating with the impurities present in the water and these impurities will now flocculate together with the Fe(OH)3 flocks. After flocculation and flotation the water is passed through ultrafiltration and reverse osmosis. Sludge is dewatered in a conventional chamber filter press. The water will be recycled to the fresh water supply for reuse. Normal water recycle rates are about 90%. In case the RO brine can be concentrated and crystallised on a commercial scale, recovery rates will go up to well above 95%.