KerWas: Thin-walled, ceramic membranes with adapted wettability and high volume specific membrane area for nanofiltration and membrane distillation for the sustainable treatment of saline waters

In this project, thin-walled ceramic membranes of adapted wettability and high volume specific membrane area are to be developed and tested for the sustainable treatment of mining waste water by means of nanofiltration and membrane distillation.

With regard to turbidity and scaling, the filtration of mining water is associated with a high risk of abrasion and module blocking, which is why the use of ceramic membranes makes sense. At the same time, these are high volume flows, so that large membrane areas are used and inexpensive membranes with a high volume specific membrane area are required.

The consortium covers the entire value-added chain from membrane development to membrane production, process development, plant construction and application.

Objective

The aim is to develop ceramic membranes made of silicon carbide (SiC) and aluminium oxide (Al₂O₃) in the form of honeycombs and hollow fibre bundles with hydrophobic macropores for membrane distillation and hydrophilic nanopores for nanofiltration.

The use of porous ceramic honeycombs and hollow fibre bundles considerably reduces the manual handling effort and thus the production costs. However, the narrow, thin-walled, large-volume components and their use in cross-flow filtration and membrane distillation pose high material challenges in terms of design, extrusion, fault-free coating with NF membranes and the targeted adjustment of wettability.

Focus of work

The project KerWas deals with the following areas of work:

• Development of honeycomb-shaped support geometries with 10 m² membrane area per membrane element (calculation of flow, substrate design, tool design, tool construction, extrusion, firing, handling of heavy membrane elements, characterization)
• Development of pressure-stable membranes on SiC supports (pressure-stable SiC supports, coating, characterization)
• Development of hydrophobic hollow fiber bundles with up to 1 m² membrane area per bundle (hollow fiber spinning, bundling, bottling, firing, hydrophobing, characterization)
• Coating of Al₂O₃ honeycombs (intermediate layers, NF-coating, characterization)
• Hydrophobic honeycomb-shaped membranes (hydrophobicity, characterization)
• Process and plant development (nanofiltration and membrane distillation plants for laboratory and pilot tests under consideration of the high salt content, especially chloride)
• Laboratory experiments to determine optimal operating parameters and operating modes
• Practical application (acidic mining waters, flowback waters, brine from potash mining)