Project duration: 15 October 2018  – 31 December 2021


The Credit project will develop a novel technology concept for water treatment and chemical recovery of highly concentrated low-value sulfate waste from a battery chemical plant. The project will provide an economically feasible bipolar membrane-based technology concept for acid and base production, which reduces environmental discharge. The demonstration and scale-up at the Sotkamo mine will provide the first reference to Suez for marketing the concept.

The solution (technology)

The project aims to scale-up bipolar electrodialysis (BPED) technology for recycling sodium sulfate in hydrometallurgical processes by converting it to sodium hydroxide and sulfuric acid. Tightened regulations for the release of sodium sulfate to the environment, its low value with high processing costs and the savings in chemical costs are the key issues for recycling. The amount of sodium sulfate waste in mines and mineral processes will grow considerably in the future as the need of battery chemicals for energy storage and electric vehicles is continuously increasing.

BPED enables efficient recycling of process chemicals resulting in economic and environmental benefits including higher utilization of raw materials and less waste and discharge from hydrometallurgical processes in general. The concept is well in line with the advancement of the circular economy strategy giving new prospects for boosting European innovations and new business opportunities within the raw materials sector. There are potentially 250 mines in Europe that could utilize the process.

Successful up-scaling of the proposed technology would enable a more advanced treatment of sodium sulfate-containing waste streams compared to the existing conventional ones such as evaporation and crystallization.


  • Teknologian tutkimuskeskus VTT (Technical Research Centre of Finland Ltd. VTT), Finland (Lead Partner)
  • Aalto-Korkeakoulusaatio (Aalto University), Finland
  • SUEZ Groupe SAS, France
  • SUEZ Water Technologies and Solutions, Belgium
  • Suomen Malmijalostus Oy (formerly Terrafame Group Oy), Finland