Ultrapure Water Systems for Hydrogen-Based Steelmaking

Pure Water Group was selected by UNIHA Wasser Technologie GmbH to design, manufacture, and supply two Continuous Electrodeionization systems delivering a combined 234 m³/h of ultrapure water. The systems were deployed as part of an industrial water treatment solution supporting green hydrogen generation for low-carbon steelmaking.

Water quality requirements behind hydrogen steelmaking
Steel production remains one of the most energy-intensive industrial processes, with conventional blast furnace routes generating substantial CO₂ emissions. In this project, hydrogen-based steelmaking was implemented to reduce emissions across the value chain. A critical dependency of this approach is the availability of stable, high-purity water for hydrogen electrolysis, as water quality directly affects electrolyser efficiency, reliability, and service life.

The supplied CEDI systems were designed to produce ultrapure water suitable for feeding a 100 MW electrolysis plant. At this scale, consistent ionic purity is required to prevent membrane degradation and efficiency losses during continuous hydrogen production.

Role of CEDI in the treatment train
Each CEDI unit provides 117 m³/h of ultrapure product water and operates as a polishing step within UNIHA’s broader turnkey water treatment concept. The overall system integrates pretreatment, reverse osmosis, electrodeionization polishing, and industrial process water supply to ensure stable inlet conditions for the electrolysers.

CEDI technology removes residual ions using electrically active membranes and resins without the need for chemical regeneration. This enables continuous operation with predictable water quality, aligning with the reliability requirements of large-scale electrolysis systems used in green hydrogen production.

Supporting decarbonization in steel production
The ultrapure water produced by the CEDI systems feeds hydrogen electrolysers that generate green hydrogen as a substitute for coal in traditional blast furnace operations. Replacing fossil carbon inputs with hydrogen enables significant reductions in CO₂ emissions across iron reduction and downstream steelmaking processes.

By integrating CEDI technology into the hydrogen supply infrastructure, the project addressed both water efficiency and process stability, two prerequisites for climate-neutral steel production at an industrial scale.

Industrial collaboration and system integration
The project reinforced the technical collaboration between UNIHA Wasser Technologie GmbH and Pure Water Group, combining system integration expertise with high-capacity ultrapure water production. Within the steel and energy sectors, the deployment illustrates how advanced water treatment technologies underpin emerging hydrogen-based industrial processes and their decarbonization targets.

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