Future (waste)water treatment demands innovative solutions that use nontoxic chemicals, generate less polluting waste streams, and reduce carbon footprint. Biobased flocculants recovered from low-value waste streams are potential sustainable alternatives to synthetic flocculants used in drinking water production, wastewater treatment and sludge dewatering. Although useful chemicals, synthetic flocculants pose risks to the environment since they may create accumulation of microplastics or release toxic components such as acrylamide when discharged in aquatic ecosystems. Furthermore, cationic flocculants are particularly useful for sludge dewatering, but high doses may inhibit biological sludge stabilization and prohibit sludge application in soils. To circumvent such risks, we aim to replace synthetic flocculants with nontoxic, biodegradable flocculants with properties tuned for specific applications. Since many biobased alternatives derived from, for example, plants or crustaceans require energy and chemical intensive production processes, often with toxic chemicals, their production results in high prices and poor sustainability. This project will focus on obtaining alternatives from wastewater thereby enabling resource recovery and application of safer sustainable flocculants.
Research challenge
The research challenge is to design processes to enrich and recover biopolymers with desired functional groups produced by mixed microbial cultures from wastewater and demonstrate their potential applications as flocculants in selected specific applications. First, a biological process will be established to convert organic matter present in wastewater into biodegradable, nontoxic bioflocculants. Although pure cultures can produce biopolymers of known and desired properties, axenic operation, low yields and costly carbon sources result in high production costs. The use of wastewater and non-axenic cultures is intended to decrease costs and enable resource recovery into valuable compounds. Secondly, separation and purification methods will be developed to achieve efficient biopolymer recovery and ensure functionality as flocculants. Finally, the recovered biopolymers will be chemically and structurally characterized beyond the common practice of bulk characterization. Finally, their potential for flocculation, flotation and other applications will be evaluated at laboratory scale.
Your assignment
Your work will focus on evaluating microbial growth and biopolymer formation under a range of operational conditions in batch and lab-scale bioreactors using well-defined synthetic substrates and eventually actual wastewater provided by industrial partners. You will study several purification approaches and analyze biopolymer characteristics (e.g., molecular weight, monomeric composition, functional groups) using different colorimetric and analytical techniques (LC-OCD, FFF-MALS, FTIR). You will perform flocculant applicability tests for various scenarios under controlled conditions (ionic strength, pH, particle type, particle hydrophobicity) to understand the relation between biopolymers properties and their performance as bioflocculants as compared with commercial synthetic flocculants.
Your profile
You are a highly motivated researcher who enjoys working in a multidisciplinary, international team. You hold a MSc degree in Environmental (bio)technology, Bioprocess engineering, Chemical engineering or related. You are fluent in English and have excellent writing skills. You have experience with wastewater treatment processes, bioreactors and biopolymers. You have interest in applying microbial physiology, organic chemistry and colloid science principles to flocculant applications for practical purposes. You take initiative, are comfortable with exploring topics beyond your current expertise and able to work independently within a team.
Keywords: biopolymers; wastewater treatment; biotechnology; bioflocculants
Supervisory Team:
Wageningen University: Prof.dr.ir. Adriaan Mels (promotor), dr. Dainis Sudmalis (co-promotor)
Wetsus: dr. Carlos Contreras-Davila (co-promotor)
Project partners: Natural flocculants – 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/
