PROJECT DESCRIPTION
BACKGROUND
As the global population grows and the climate warms, water scarcity is raising mounting concerns for food production in the 21st century. The challenge cannot be met without engaging with industry. Guzzling about 40% of the water consumed in the EU, industrial players are some of the main users and polluters of water resources. Mining and quarrying currently produces 7% of all wastewater discharged in the EU. The sector relies on plentiful water supplies to separate ores and metals from rocks and transport raw materials to processing sites. It has a vested interest in recycling the water that it uses. Furthermore, economies of scale in the industry offer unparalleled opportunities for pioneering water saving and recovery technologies prior to their broader roll-out.
OBJECTIVES
The goal of the REMINE-WATER project was to conserve water resources and protect natural environments from discharges of industrial process brines. A new set of water treatment technologies purified effluents from mining and metallurgy operations. Project partners designed, built and operated these technologies in facilities used for processing minerals. The treatment line combines innovative membrane-based technologies, the application of low temperature heat integrating renewal energy (e.g. solar) and electrochemistry. It notably reduced the greenhouse gases emitted by current wastewater treatment techniques, in line with the Industrial Emissions Directive. The technologies fielded in the project removed salt from industrial brine. recovering water and also extracted acids and metal salts to offer them a second life, supporting the EU circular economy strategy and the roadmap to a resource efficient Europe.
RESULTS
The goal of the REMINE-WATER proposal is to protect the environment from discharges of industrial process brines (e.g. high salinity) and to contribute to circular economy through the recovery of water, metal salts and strong acids and their on-site valorisation. REMINE-WATER has tackled this objective by developing a new water treatment process train that was designed, built and operated in a mineral processing industry.
Following a challenging beginning that required a change in testing location, the project was ultimately executed successfully, demonstrating the technical, environmental and economic feasibility of the solution.
Quantitatively, the beneficiaries treated more than 18,500 m3 of wastewater with the pre-treatment of the zero liquid discharge pilot plant, more than 12,000 m3 with the nanofiltration (reaching effectiveness of 70%) and nearly 8,000 m3 with the reverse osmosis (reaching effectiveness of 90%, so producing more than 7,000 m3 of permeate). Qualitatively, the permeate produced with both the nanofiltration and the reverse osmosis has much better quality than the effluent produced with the current water treatment at MATSA: 30 mg/l of sulphates the permeate of the nanofiltration, no sulphates registered in the permeate of the reverse osmosis and 1,500 – 2,000 mg/l of sulphates currently discharged by MATSA. In addition, the results show a reduction of water consumption (50%), salinity (60%) and OPEX (50% reduction compared to conventional thermal brine concentration).
The results from the resource recovery approach proposed by the project are not conclusive enough, indicating that the technology is not ready to be implemented yet. The plan is to continue testing the 3D-electrodeposition unit and to upscale it to a bigger pilot scale.
The current legal framework in the project region (Decree 109/2015, approving the Regulations on Discharges into the Hydraulic Public Domain and the Maritime-Terrestrial Public Domain of Andalusia) established emission limit values for certain parameters, and specifically for sulphates. Andalusian mining companies in general, and MATSA in particular, find it difficult to guarantee compliance with these emission limit values despite the use of BATs and the application of innovative technologies and processes. As a consequence, although the limit established in the Decree 109/2015 for sulphates is 900 ppm (and 750 ppm of monthly average), some of the companies (as MATSA) are operating with a transitory permit of higher concentration of sulphates. The project can be the turning point for that situation, as it has demonstrated a technology which allows the mining industry reaching the general limit. This will be the main driver for the replication of the project solution. In fact, it is planned that MATSA will implement it at full scale in the short-medium term at their mines of Minas de Aguas Teñidas and Magdalena.
