Wiser with Metal

This practical study investigates how much aquafer can be reprocessed into iron powder of a known quality. If pure enough, the iron powder can be used for a range of high-grade applications, including as a carrier material for sustainable energy. Specifically, the study is looking at the potential of this powder as a circular fuel and as a material for compact hydrogen storage.

Aquafer from drinking water production as a raw material with socially relevant applications

In many cases, the production of drinking water releases an iron-rich residual stream: aquafer. At present it is mostly reused once – possibly after thickening – in fermentation plants to adsorb sulphur from biogas. A feasibility study has demonstrated that dried aquafer can be converted to iron powder through hydrogen reduction. Depending on the level of purity, this iron powder has a range of applications.

A developing and promising application is as a circular energy carrier. The use of sustainable energy sources during aquafer drying and iron powder production allows for the compact and safe storage of sustainable energy and its release when those sources are not available. As a result, iron powder can help to achieve a better balance in the supply and demand of sustainable energy.

From dried aquafer to iron powder.

Aquafer as a source of sustainable iron powder: production, production quality, feasibility and social impact

In this project, existing residual streams of aquafer released during the treatment of  groundwater and surface water are dried and then reduced with hydrogen to iron powder. The extent to which there are seasonal effects on the quality of aquafer from surface water treatment is being investigated. In addition, studies are being conducted into the appropriate pretreatment and aeration of aquafer obtained from the treatment of groundwater. The purer the aquafer, the higher the quality and applicability of the iron powder.

The conversion process of aquafer to iron powder itself is being optimised on the laboratory scale in conditions that are relevant for practice. Research looking at the reduction process is focusing on:

  • the pretreatment of the dried aquafer;
  • the amount of time during which reduction with hydrogen occurs;
  • the temperature at which reduction with hydrogen occurs.

The technical results will then be formulated in terms of the social and economic impact. If the potential is proven, a preliminary design for a plant will be produced to further scale up this valorisation pathway.

Social and technical/economic impact

The project deliverables will be:

  • mapping the potential to upgrade existing aquafer residual streams from the treatment of groundwater and surface water into energy carrier material;
  • survey of the options to enhance the purity of those residual streams;
  • delivering fundamental insights into the process itself and into the fate of, for example, organic micropollutants by testing the reduction process on the laboratory and semi-industrial scale;
  • clarity relating to the market potential of the iron powders produced by testing applications, which is essential for the ultimate implementation in practice;
  • a society-wide impact analysis in which application trials will provide crucial insights.

This information will allow for the identification of the potential of the Dutch water sector for the circular deployment and disposal of aquafer residual streams.