Layered Biofiltration for drinking water production
Layered biofiltration to improve the biological removal of organic carbon species in drinking water production
Biofiltration is a sustainable approach to produce drinking water, as it harnesses microbial activity to effectively remove organic matter, pathogens, and pollutants, ensuring safe, high-quality water, while reducing reliance on chemicals. Biofilms play a critical role in biofiltration, as these structured microbial communities, adhered to filter media surfaces, are the primary mechanism accelerating organics removal in systems like granular activated carbon (GAC), slow sand filtration (SSF), and rapid sand filtration (RSF). GAC-based methods, due to adsorption, usually excels in complex contaminants removal, while SSF and RSF prioritize pathogen control and scalability, respectively. Hybrid GAC-sand systems may enhance both, ensuring safe, sustainable water treatment. In particular, the combination of GAC with other low-cost filter media, such as sand, could reduce the costs of adsorption systems for organic pollutants removal. Past research investigated a GAC sandwich SSF system as an attractive solution for tertiary wastewater treatment. In this layered biofiltration, an upper layer of sand host on its top a biofilm (called schmutzdecke) which plays an important role in water purification. A middle GAC layer acts as a non-backwashed adsorbent which can remove contaminants that cannot be biodegraded. Finally, a lower sand layer minimises the potential of biological particles and GAC fines in the effluent.
Research challenges
Composition of influent water influences biodegradation in biofilters and thus their overall performances. For instance, complex organic matter like humic substances can be biodegraded to intermediate products (“building blocks”, weight range of 350–1000 Da). This is a transitional category between larger humic substances (1–20 kDa) and smaller low molecular weight (<350 Da), which can outcompete organic micropollutants adsorption onto GAC, reducing their removal. Layered biofiltration could help overcome and optimize these sort of issues.
We will investigate layered biofiltration, testing different combinations of carbon and sand media in lab-scale biofilters, and test them against different type of influent water, aiming to optimize and develop a new biofiltration approach that could overcome current limits of using carbon or sand filtration alone. Within these systems, we will understand how different microbial communities will develop as active biofilms and which abiotic processes will take place (adsorption, desorption, etc.). Our reference will be real-scale scenarios proposed by the Dutch drinking water companies project partners.
Your assignment
You will design your own lab-scale layered biofilters with the support of the Wetsus technical team, and operate them applying different conditions, understanding the effect is of their structure and operation (contact time, height, etc.) on removal of organic species from either groundwater or surface water. You will study which biological and physical-chemical processes occur in the different layers, to optimize biofiltration performances towards certain organic carbon species. To analyse abiotic and biotic processes inside the biofilters you will use a multidisciplinary approach, applying analytical techniques like chromatography (i.e. IC, LC-OCD, HPLC, GC) surface characterization (i.e. BET, AFM, SEM-EDX), as well as microbiological techniques based on microscopy (optical, epifluorescence, CLSM, SEM) and molecular biology (i.e. Next Generation Sequencing, Transcriptomics). You will closely interact with the company members of the Biofilms Theme to optimize the process in connection with real scale scenarios, while getting useful suggestions to improve your research.
Your profile
You must hold a MSc degree in Biotechnology, Environmental Technology, Environmental Engineering, Chemical Engineering or related fields. It is mandatory to have previous experience on both bioreactor/biofilters design and microbiology. Experience in microscopy or modelling is a plus. You are an ambitious and curious researcher who likes to work in a team and is thrilled by scientific discovery.
Keywords: Biofiltration, Biofilms, GAC sandwich, water treatment, biodegradation
University promotor/University group: prof. Annemiek ter Heijne, Wageningen University, Department of Environmental Technology.
Wetsus co-promotor and daily supervisor: Dr. Maria Cristina Gagliano, Theme Coordinator Biofilms and Senior Researcher.
Wetsus co-supervisor(s): Dr. Amanda Larasati, Theme Coordinator PFAS and Researcher; Inez Dinkla, Theme Coordinator Monitoring & Quality and Senior Manager.
Project company partners: The project will be carried out within the Biofilms Theme (https://www.wetsus.nl/research-themes/biofilms/) with Evides, Vitens, WLN and Brabant 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/
