Topic background: Agricultural productivity depends on the availability of N, P, and K fertilizers. Production of these fertilizers requires massive amounts of raw materials and fossil fuels. After food consumption, the fertilizers end up in organic waste streams, requiring treatment using additional energy and chemicals. Therefore, our linear use of fertilizers leads to the depletion of critical resources and contributes to extensive environmental damage like eutrophication and climate change. Producing fertilizers from food-associated and source separation based waste(water) is of great benefit for society as nutrients for agriculture get recycled, which leads to fewer resources depletion and prevention of environmental damage. Electrochemical systems are exceptionally well suited for producing these circular fertilizers as renewable electricity can be used, and no chemicals are needed.

Research challenges: Electrochemical separation technologies have been mainly studied for desalination and, to some extent, for N removal. In this project, we will explore the future potential of electrochemical separation technologies to produce novel and valuable fertilizers like NH4NO3 and K rich streams of high purity. Next to this, we want to reduce the occurrence of unwanted mineral precipitation (scaling) inside the electrochemical separation system. Therefore, we will investigate possible integrated solutions for chemical-free scaling mitigation. A model will be developed describing the relation between the composition of the waste streams and the performance of the electrochemical separation system. This model is crucial for studying the required integration with other conventional waste(water) treatment technologies like digestion or membrane processes.

Objectives and methodology: This project aims to develop electrochemical separation technology for nutrient recovery in such a way they become valuable fertilizers again. Different innovative processes will be studied using laboratory-scale systems. We will explore the dependency of the separation performance on waste(water) and operational parameters and describe the technology with a process model. The overall goal is to integrate the electrochemical separation technology in general process schemes, including conventional wastewater treatment technologies and separation at source sanitation concepts. The experiments with the prototypes will supply data for model validation.

We are looking for a highly motivated student with a background in environmental technology, electrochemical or process engineering. The ideal candidate should be a team player with excellent communication skills. Experience with electrochemical separation technologies (like ED or CDI) systems is required, while experience with physical-chemical modelling of aqueous systems is considered a clear advantage.

Salary and working conditions are according to the collective labour agreement of the Cooperative Association of Dutch Universities (VSNU) for PhD students.

Wetsus, European centre of excellence for sustainable water technology is a facilitating intermediary for trendsetting know-how development. Wetsus creates a unique environment and strategic cooperation for development of profitable and sustainable state of the art water treatment technology.

The inspiring and multidisciplinary collaboration between companies and research institutes from all over Europe in Wetsus results in innovations that contribute significantly to the solution of the global water problems. Wetsus’ scientific research program is defined by the private and public water sector.

Read more about our current PhD program. All info about the research at Wetsus can be found here.