PhD in Polyhydroxyalkanoate (PHA)-based colloids from wastewater

Fabrication of polyhydroxyalkanoate (PHA)-based colloidal release systems for agrochemicals 

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. A PHA-rich biomass is readily produced, and PHA is readily recovered, but scale up in a context of meaningful biopolymer applications stands to have significant bearing on the success of the industrial process.  In this project, the focus is on relevant PHA application development that is integrated to methods of the polymer recovery starting from a PHA-rich biomass. 

Today, to enhance the viability and ensure storage stability of seeds, they are modified by thin polymer coatings based on polyurethanes, poly(ethylene-co-acrylic acid)s or polyesters. These synthetic polymers are also used in fertilizer coating formulations to improve crop yields, and mitigate eutrophication, by engineering the controlled release of macro- and micronutrients. Such synthetic polymers, as functional additives with agricultural products, are effective but not degradable.  They can contaminate soils as microplastics with associated risks for the environment causing hazards to the biosphere and human health.  There is a need for fabrication of PHA-based functional coatings in agriculture, and to establish a supply chain of biobased coatings that do not contaminate.

Research challenges

The research challenge is to establish the “tools” of method and process to formulate and realize such coatings starting from a PHA-rich biomass: “Which processing techniques are best for the efficient variation of the thickness and morphology of PHAs-based coatings on seeds, urea fertilizer, and microgel carriers?”; “How to control the release time of active ingredients and degradation time of PHA coatings?”.  In following successful “tool” building, the functional attributes of prototype products can be critically evaluated and optimized: “What is the impact of PHA-based formulations on the environment (soil and ground waters)?”.  This project is 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 production from Dutch regional municipal wastewater treatment residuals.

Your assignment

The research is interdisciplinary, involving applied microbiology, chemical engineering unit processes, and polymer science.  You will develop coating of seeds, urea fertilizer, and microgel agrochemical carriers based on PHAs. You will apply commercial seed/urea fertilizer coating techniques (dry coating, rotary pan, and pelleting pan) to explore different types of PHA coatings on seeds/urea fertilizer, like seed dressing, film coat and encrustment, to vary the thickness and morphology of the PHA layer. For microgel coatings precipitation methods will be applied for controlled encapsulation with PHA layers. Developed coating methods will allow regulation of the thickness, porosity, and chemical composition of PHA coatings. Ability to integrate different active ingredients (micronutrients, biostimulants, antibacterial agents etc.) into PHA-based coatings are to be demonstrated. You will evaluate the physico-chemical properties of PHAs-based coatings with analytical techniques such as a: 1H-NMR, FTIR, and Raman spectroscopy (chemical structure); b: electron microscopy SEM, TEM (layer morphology); and c: thermal analysis DSC, TGA (thermal stability). The loading and release of active ingredients into PHA-based coatings can be evaluated by UV/VIS, HPLC or GC analysis. The degradation of PHA-based coatings in aqueous solutions and in soil can be monitored by GPC and gravimetric analysis. Ultimately, the goal is that the mechanical wear resistance, storage stability and in-situ performances for selected prototypes of coated seeds, urea fertilizer, and microgel agrochemical carriers will be performed.

Your Profile

You are a self-driven chemical engineer and/or with interest and experience in polymer science 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 process, analytical methods, data analysis, and modelling towards fundamental insights. 

Keywords: resource recovery, biobased biodegradable biopolymers, coatings and gels, controlled release systems, sustainable agriculture

Supervisory Team: University promotor and co-promotor: Prof. Dr. Andrij Pich (RWTH Aachen University/DWI University of Maastricht/AMIBM)

Wetsus supervisor: Dr. Alan Werker (Biopolymers from water theme leader, Wetsus)

Project partners:  Biopolymers from water

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/