6.14 Improved recovery of phosphorus through manipulation of iron phosphorus chemistry using Mössbauer spectroscopy

The EU has identified phosphorus as a critical raw material and recovery of phosphorus is highly relevant. The transition to a bio-based society requires a circular approach to management of critical nutrients like phosphorus to maintain production of biomass at high levels. Closure of phosphorus cycles requires production of high quality recovery products from low concentrations in wastewater. Adsorption has a high potential to remove phosphate from wastewater at low concentrations and to produce a concentrated, high quality phosphate product that can be reused.

Research challenge
Already granular iron oxides are available for phosphate adsorption but their technical and economic performance needs improvement through increased adsorption capacities and stability during regeneration. In this project we develop efficient and cost effective iron based adsorbents for phosphate recovery from wastewater and surface water at low concentrations. Such a process requires adsorbents with high capacities that can be regenerated easily and reused multiple times. Literature and our own research show that different iron oxides show different behavior for phosphate adsorption and desorption. In this project we want to understand how to tune the iron oxide chemistry and the nano- and microstructure of the iron based adsorbent to achieve the best possible adsorbent.

Mossbauer spectroscopy offers unique capabilities to follow and understand the (trans)formation of amorphous and nano-crystalline iron structures that cannot be identified with conventional analytical tools like XRD. For instance we intend to use Mössbauer spectroscopy to better understand the binding interaction between phosphate and different types of iron oxides. Furthermore we expect to be able to follow transformations in the structures or iron oxide adsorbents and subsequent phosphate adsorption capacities during several cycles of adsorption and regeneration.

We are looking for a candidate with an MSc degree in the field of chemistry or physics with excellent experimental skills. Knowledge of adsorption processes or iron chemistry is useful. The candidate should be interested to learn and understand the fundamental aspects of Mossbauer spectroscopy.

The research project is part of the Wetsus research theme Phosphate Recovery.
The following companies are part of the theme: Kemira (, ICL fertilizers (, Green Water Solution (, STOWA (, Water Authority Brabantse Delta (, Oosterhof Holman (

Promotor: G.J.W. Witkamp, TU Delft, Environmental Biotechnology Group.
Prof. Dr. Ekkes Bruck, TU Delft, Department Radiation, Science & Technology/Fundamental Aspects of Materials and Energy
Wetsus supervisor: Ir. Leon Korving

For more information contact Leon Korving:

Wetsus, Leeuwarden, The Netherlands


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