Background - Leading developments and innovations with methods for biopolymer (polyhydroxyalkanoate or PHA) production and recovery, using wastewater and organic residuals as carbon sources, are undertaken within the Wetsus theme Biopolymers from Water. This theme bridges science and engineering in bioprocess and materials.  It is with potential for meaningful downstream societal contributions and industrial opportunities from biopolymers produced and recovered as a part of water quality engineering services. The Dutch Water Authorities act on goals of renewable resource cycles (Routekaart Afvalwaterketen tot 2030), wherein energy, mineral, and biopolymer products are to be parallel value-added outcomes to the principal task of environmental protection from treating municipal effluents. This research project will be to contribute with innovations in fundamental details of bioprocess in anticipation and cooperation within ongoing steps to scale up and integrate industrial scale PHA production from municipal waste.  Research questions will relate to key factors that ultimately stand to have significant bearing on the success of scaled up process through anticipated influences on production productivity, economy, and polymer quality (value).

Research challenges - PHA production at industrial scale requires skills and technique in fed-batch bioprocess, and its control.  A sufficient mass of VFA rich substrate must be supplied in the right way to a mass of polymer accumulating activated sludge.  Principles of process need to manage the polymer quality with respect to co-polymer composition and molecular weight distributions, and mitigate flanking microbial population activity and growth, while maintaining optimal overall metrics of the economics in productivity.  Innovative industrial scale bioprocess methods, based on exploiting fundamental principles of biomass dynamic response and polymer storage kinetics, are required for a successful robust upscaled design.  These details are novel to the industry, and they will be essential in anticipation of successful industrial scale facilities.  This project is also about fundamental innovations that can come from connecting a spectrum of ideas and principles together, and it is directed with purpose towards the real-life goal for the Dutch water authorities to successfully scale up technology for PHA from Dutch regional municipal wastewater treatment residuals.

Objectives and methodology - The research is interdisciplinary, involving applied microbiology, process monitoring and control, and polymer science.  The project will apply practical bioprocess experimental work at laboratory and pilot scales, alongside modelling and applying theory and observations, of biomass response, monitoring and control, towards effective advanced process solutions.  The objectives are to:

• Define and optimize specific requirements of method and bioprocess to reliably produce PHAs with municipal surplus activated sludge using volatile fatty acid (VFA) rich streams coming from acidogenic fermentation of municipal primary sludge.
• Optimize the process with respect to exploiting flanking populations of nitrifying bacteria in the activated sludge while mitigating growth of other bacteria that would reduce productivity.
• Optimize the process with respect to predictable control of polymer quality through the biological production, but also through post accumulation, and recovery/purification steps.
• Integrate findings and developments of this work through techno-economic evaluation and with direct link to the demonstration plant activities of a demonstration scale project, which will be underway in parallel during the PhD project.

Students’ requirements: The candidate is a self-driven bioprocess and/or chemical engineer (MSc degree) who takes own initiatives and can also blend in team collaborative R&D.  An aptitude for practical experimental work at laboratory and pilot scales is essential, as well as skills and passion for data analysis, programming, and modelling.

Salary and working conditions are according to the collective labor agreement of the Cooperative Association of Dutch Universities (VSNU) for PhD students. Per 1-7-2021, the salary for a PhD student as determined by the collective labor agreement are (in Euros before tax per year): €34076 (year 1), €39732 (year 2), €41832 (year 3) and €43554 (year 4). PhD students are appointed by one of the three cooperating universities, but research is conducted at the Wetsus laboratory in Leeuwarden.

Wetsus

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.