Rethinking N and P removal in sewage treatment
Synergetic recovery of phosphorous (P) and nitrogen (N) from wastewater via regenerative adsorption
A circular sewage treatment plant of the future should be able to comply with increasingly tighter effluent limits while meeting high recovery rates of carbon, phosphorus (P) and nitrogen (N). Currently, in these plants N is mainly converted into nitrogen gas via biological nitrification-denitrification, causing greenhouse gas emissions and consuming a significant amount of aeration energy. N recovery using zeolite-based adsorbents has been investigated, yet zeolite regeneration and recovery of adsorbed species and are still open challenges. Similarly, P can be removed to very low concentrations and recovered using iron oxide adsorbents. At Wetsus, years of research developed knowledge on both ammonium stripping via electrochemical membrane systems and P adsorption and recovery via different routes. One of those P adsorption approaches is now a patented technology, Biophree®, scaled up with Wetsus commercial partners. A combined P and N removal and recovery via adsorption would make this a viable approach not only for safe water discharge but also for resource recovery and reuse, rethinking and improving the efficiency of current sewage treatment plants.
Research challenges
The main challenges for adsorption viability lies in the regeneration step of the loaded adsorbent. Regeneration, generally performed with chemical solutions, allows to concentrate and recover the target nutrients in the liquid phase, while reactivating the adsorbent for the next adsorption cycle. Preserving the adsorbent and its characteristics for multiple adsorption cycles is what would make adsorption an economically viable route.
Combining P and N adsorption and/or recovery is a pioneering project idea which arise additional promises and challenges. Several combinations and strategies will be explored to understand the chemistry of the process and identify a viable approach, minimizing the use of chemicals while preserving the adsorbent lifespan.
Reaching a successful proof-of-principle would revolutionize the current secondary treatment step of sewage treatment plants, paving the way towards the circular treatment plant of the future.
Your assignment
This is a multidisciplinary project, ranging from water technologies to materials science, from engineering to chemistry. As multidisciplinary researcher, you will investigate the (surface) chemistry of phosphate and ammonium species and their interaction with different adsorbents. Further than using commercially available adsorbents, you will have the chance to synthesize and modify new adsorbents. You will perform laboratory experiments from more fundamental (batch) to higher scale (continuous) settings, carrying out the analytical characterization of both liquids (water stream, regenerant) and solids (adsorbents) phases. You will investigate different strategies to produce a valuable N and/or P product from the regenerant solution. You will get acquainted with techniques such as ion chromatography, ICP-OES, TOC, XRD, FTIR and more advanced techniques such as Mössbauer Spectroscopy and SEM-EDX. Moreover, thanks to Wetsus framework, you will also benefit from the expertise and knowledge of the involved industrial partners. This ambitious project promises to be highly varied and interdisciplinary.
Your profile
We are looking for a highly motivated researcher who recently got his MSc degree in the field of environmental technology, chemical engineering, process engineering, chemistry, material engineering or a related field. You need to be able to bridge theoretical knowledge like surface chemistry to concrete process engineering concepts.
Our ideal candidate is comfortable working in an international and multidisciplinary team, and is interested in collaborating with industrial stakeholders. Creativity and outside-the-box thinking are a great addition to your skillset to come up with innovative ideas.
During your PhD, you will have the opportunity to collaborate with the stakeholders who are currently bringing the Biophree® technology to the market and the end users (waterboards). This project can potentially revolutionize sewage treatment plants!
Keywords: Resource Recovery; Wastewater Treatment; Material Science; Surface Chemistry.
Professor/University group/Wetsus supervisor(s):
University promotor and co-promotor: Prof.dr.ir. Annemiek ter Heijne and dr.ir. Paula van den Brink, (Wageningen University, Department of Environmental Technology, Biological Recovery & Re-use Technology group)
Wetsus daily supervisor(s): Dr. Carlo Belloni (Scientific Project Manager), Dr. Thomas Prot (Scientific Project Manager).
Project partners: Phosphate recovery – Wetsus
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/
