The EColoRO concept was tested at pilot scale (up to 2m3/hr) at four sites:
•Utexbel Snoecklaan (BE)-Advanced textiles for special applications
•Utexbel Ninovestraat (BE)-Yarn dying mill
•Tintoria Pavese (IT)-Cellulosic linings and cotton linings
•Setex (DE)-Fashion fabrics and home textiles
Scale-up towards demonstration plant scale, foreseen at the Utexbel site, was not further pursued due to unforeseen delays in granting of permits and additional costs related to the complexity of the wastewater. In addition, during the project the business case diluted because of tax reduction on discharge. Scale-up foreseen at Tintoria Pavese was not further pursued as the concentration of brine components exceeded the local discharge limits.
Additional studies were performed on valorisation of the sludge and concentration of the brine produced as a result of the EColoRO treatment. ECWRTI entailed a cross-market analysis, a techno-economic feasibility study, an analysis of wastewater handling, an LCA analysis and an EU wide legal scan. The project has identified the relevant factors determining the technological feasibility at individual sites, also used to create the courseware material for industry and students.
Results
Technology
The EColoRO-technology performed well at four pilot sites, achieving water 70% recovery rates. As a result of the pilot experiments, modifications were proposed to optimize the EColoRO process. Energy consumption strongly depended on the amount of oxidizable pollutants (COD) in the wastewater and the conductivity of the water, and at higher temperatures the floc formation can became more difficult.
The further treatment of brine was evaluated for three technologies (Galicos, DC-MD and air-gap MD), the Galicos system tests led to a bench scale process in a stable operation up to high concentration factors. Adsorbent in biogas installations or in filters for metals or phosphorous were identified as main possible valorization options for sudge.
Understanding the business case
The costs of application of total water re-use have to be evaluated case by case. The operating expenditures (OPEX) are determined by the type of the freshwater source, the processed volume of water, the pollution load of the wastewater and the required amount of energy for the EColoRO process and the discharge taxes. The combination of these factors does not always turn out positive; in many situations the cost of water, energy and/or discharge of waste weakens the business case. These costs are mainly dependent on local governmental policy, while on the other hand costs-cutting pressure on textile manufactures depends by buyers demands, external factors and international competitiveness.
Regulatory aspects
Obtaining permits for the discharge of sludge and brine is a difficult process and requires discussions with the local authorities. In one case, brine discharge with increased concentrations of certain pollutants can be accepted when applying extended water reuse, in another, increased concentrations of certain pollutants can result in adverse ecotoxic effects and hence brine cannot be discharged. The chemical sludge resulting from the electrocoagulation process poses another obstacle since it is considered hazardous waste and has to be transported and disposed of accordingly. To these regards, ECWRTI has been connected to the BREF revision process to stimulate enabling factors, in terms of emission requirements.
