Bipolar Membrane Electrodialysis for Sulfate Recycling in the Metallurgical Industries

Kuldeep Kuldeep, Wouter Badenhorst, Pertti Kauranen, Heikki Pajari, Ronja Ruismäki, Petri Mannela, Lasse Murtomäki*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)
381 Downloads (Pure)


Demand for nickel and cobalt sulfate is expected to increase due to the rapidly growing Li-battery industry needed for the electrification of automobiles. This has led to an increase in the production of sodium sulfate as a waste effluent that needs to be processed to meet discharge guidelines. Using bipolar membrane electrodialysis (BPED), acids and bases can be effectively produced from corresponding salts found in these waste effluents. However, the efficiency and environmental sustainability of the overall BPED process depends upon several factors, including the properties of the ion exchange membranes employed, effluent type, and temperature which affects the viscosity and conductivity of feed effluent, and the overpotentials. This work focuses on the recycling of Na2SO4 rich waste effluent, through a feed and bleed BPED process. A high ion-exchange capacity and ionic conductivity with excellent stability up to 41 degrees C is observed during the proposed BPED process, with this temperature increase also leading to improved current efficiency. Five and ten repeating units were tested to determine the effect on BPED stack performance, as well as the effect of temperature and current density on the stack voltage and current efficiency. Furthermore, the concentration and maximum purity (>96.5%) of the products were determined. Using the experimental data, both the capital expense (CAPEX) and operating expense (OPEX) for a theoretical plant capacity of 100 m(3) h(-1) of Na2SO4 at 110 g L-1 was calculated, yielding CAPEX values of 20 M EUR, and OPEX at 14.2 M EUR/year with a payback time of 11 years, however, the payback time is sensitive to chemical and electricity prices.

Original languageEnglish
Article number718
Number of pages13
Issue number9
Publication statusPublished - 18 Sept 2021
MoE publication typeA1 Journal article-refereed


  • bipolar membranes
  • electrodialysis
  • ion-exchange membranes
  • sodium sulphate
  • Sodium hydroxide
  • sulfuric acid
  • electrotransport


Dive into the research topics of 'Bipolar Membrane Electrodialysis for Sulfate Recycling in the Metallurgical Industries'. Together they form a unique fingerprint.

Cite this