Upgrading and valorisation of vivianite recovered from sewage sludge
Upgrade and valorisation of vivianite minerals recovered from sewage sludge
Considering the imbalance in phosphate rock distribution across the globe and the absolute need for phosphate fertilizer to ensure food production, its recovery from secondary sources is essential. If all the phosphorus present in sewage sludge would be recovered in Europe, we could cover around 30% of our needs; a significant fraction!
Over the past 10 years, our research group has been the world’s frontrunner in the recovery of phosphorus from sludge under the form of vivianite. Vivianite is a blue iron phosphate mineral forming in anaerobic environment like digested sludge or animal manure. Thanks to its paramagnetic properties it is possible to extract it magnetically.
This extraction process, called Vivimag®, has been patented and our industrial partners are bringing it to the market through the construction of the first demonstration scale installation. For this technology to be successful, it is important to strengthen the valorisation strategies.
Research challenges
There are two main routes for vivianite valorisation: the separation of the iron and the phosphorus, or the direct reuse of the mineral. Based on previous research, it is known that producing iron products and phosphorus fertilizer from vivianite can be done via different chemical leaching approaches, but this has never been studied in depth.
Several options exist to directly reuse vivianite, and one of them is to use it as a precursor to produce Lithium-iron-phosphate (LiFePo) batteries. Preliminary results showed that this route is promising. However, vivianite crystalized in sludge contains organic and inorganic impurities which could either be a challenge or an opportunity.
If vivianite purification is needed, different purification strategies need to be developed to target organic and inorganic impurities, with the latter being also present in vivianite’s crystalline structure itself.
Your assignment
The main objective of this project is to develop valorisation routes for vivianite. You will investigate the potential and challenges of vivianite purification, for example via recrystallization. In parallel, the development of an efficient gravity-based purification process could be investigated. You will then study the direct reuse of vivianite, firstly as a precursor for LiFePo batteries. Later, you will also scout for other original and novel options to valorise vivianite. You will have access to advanced characterization techniques like SEM-EDX, XRD and Mössbauer spectroscopy to support your 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.
Your profile
We are looking for a highly motivated researcher with a recent MSc in either chemical engineering, process engineering, chemistry, material science or a related field. You need to be able to bridge fundamental knowledge like crystallization science with applied process engineering concepts.
You are comfortable working in an international and multidisciplinary team and are interested in collaborating with the industrial stakeholders. Creativity and out-of-the-box thinking are a great addition to your skillset to come up with innovative ideas to valorise vivianite.
During your PhD, you will have the opportunity to collaborate with the stakeholders who are currently bringing Vivimag® technology to the market and those in charge of developing new value chains for vivianite. It will be a very exciting project with a concrete impact on the field of resource recovery!
Keywords: Phosphate recovery, crystallization, material characterization, wastewater, LiFeP batteries
Professor/University group/Wetsus supervisor(s):
University promotor: to be announced
Wetsus daily supervisors: Thomas Prot (Scientific Project Manager) and Carlo Belloni (Scientific Project Manager)
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: https://phdpositionswetsus.eu/guide-for-applicants/
