phd project

Developing iron oxide adsorbents and regeneration strategies for phosphate recovery from surface water

Phosphorus (P) is an essential nutrient for life and fundamental for food production sustainability. It is obtained from phosphate rock mines (present in a few countries), mainly to produce fertilizers. Through agricultural run-off and sewage effluent, P ends up in water, where it accumulates. Already at concentrations > 10 µg/L it can promote eutrophication and algae blooms. Therefore, it is crucial to remove P from water to ultra-low concentrations and to recover it. In our research group we see adsorption as a technology able to achieve these targets. We have gained quite some experience using iron oxide-based adsorbents and industrial partners of Wetsus are scaling up this technology for practical use. This project supports this by developing a more fundamental understanding of the process to enhance the viability of this approach.

Research challenges
For adsorption economic viability, the reusability of the adsorbent and its ability to sustain multiple adsorption-desorption cycles are fundamental. Nevertheless, little focus has been spent on the adsorbent regeneration. Regeneration is usually performed through an alkaline wash (pH > 13), where P accumulates to then be recovered. Such use of harsh chemicals might deteriorate the adsorbent, reducing its performances and lifespan. Moreover, losses of the regeneration solution (e.g., hydroxide retention by the adsorbents), challenging pH neutralization after regeneration, and exhaustion of the regeneration potential, among others, make this a critical step. Improving the regenerability and reusability of the adsorbent and optimizing the regeneration procedure would provide a boost to the viability of adsorption technology for P recovery.

Your assignment
This project aims at improving the adsorbent stability and regeneration procedure efficiency during P recovery. Passing from process engineering to chemistry, from material science to physics, this project covers fundamental aspects, as well as applied research. You will benefit from both the academic scientific knowledge at TU Delft and Wetsus as well as the on-field expertise of the commercial partners. You will synthesize iron oxide-based adsorbents, manipulate, test for P recovery, and compare to commercial standards. You will investigate the interaction of phosphate with iron oxides, of the regeneration solution, with the adsorbent and the adsorbed phosphate, and the resulting effect on the adsorbent. For this you will apply advanced techniques, such as Mössbauer spectroscopy, XRD, and FTIR, among others. Such fundamental investigation will outline the strategy to improve the regeneration procedure. Moreover, a better understanding of the Fe-O-P bond will provide you insights to develop novel, chemical-free, regeneration methods.

Your profile
We are looking for a highly motivated student with a background in either environmental technology, chemical engineering, process engineering, chemistry or physics. You need to be able to bridge chemical engineering with more fundamental understanding of the physical chemistry involved in the binding of phosphate and to have an affinity and interest in the physics behind the advanced analytical techniques, such as Mossbauer spectroscopy. You should be open minded and a team player, in order to work in a multidisciplinary and multicultural environment.

Keywords: phosphate recovery, water technology, adsorption, material development, nanoparticles.

Supervisory team: Prof.Dr. Ir. Doris van Halem (Delft University of Technology), Dr. Iulian Dugulan (FAME, Delft University of Technology), Leon Korving (Wetsus), Carlo Belloni (Wetsus).

Project partners: Phosphate Recovery theme

Only applications that are complete, in English, and submitted via the application webpage before the deadline will be considered eligible.

Guidelines for applicants:

The call is closed. Please be informed that we no longer accept applications for the current call. We thank you for your interest.