Clean groundwater is an essential source of drinking water. However, our use of pharmaceuticals, household chemicals, and pesticides is leading to the release of increasing quantities of organic micropollutants. These chemicals enter the water cycle via wastewater effluent and agriculture runoff, and subsequently infiltrate into groundwater, threatening water quality. Groundwater contains naturally occurring microorganisms that can biodegrade contaminants. However, these specific micropollutants present a challenge to successful biodegradation due to their complex structure and low concentrations. Very little is known about the biological mechanisms in water systems that enable micropollutant biodegradation. I aim to elucidate the fundamental set of factors that control the biodegradation of micropollutants in groundwater. My approach is multidisciplinary: I will use geochemical and microbiological techniques to perform fundamental laboratory research and apply this in field experiments. First, to obtain a mechanistic understanding of micropollutant biodegradation, I will perform laboratory experiments to examine the roles of redox conditions and dissolved organic carbon on the biodegradation of a select list of micropollutants. Second, I will characterize biological activity and biodegradation at field locations using novel advanced monitoring methods, including DNA-based techniques and isotope analysis. Finally, I will take a step towards developing robust and reliable technologies for micropollutant biodegradation. My findings will provide the necessary fundamental scientific framework for prediction and application of biodegradation of micropollutants in groundwater as well as other portions of the water cycle. Thanks to my multidisciplinary background and my experience in designing scientific investigations at field locations, I am well qualified to perform fundamental scientific research projects of this scale and complexity. I will work closely with the drinking water institutions Vitens and Water Laboratorium Noord (WLN), who will provide access to drinking water production sites and financial support. Their involvement ensures that my results will be developed further and applied in practice.

Anaerobic reactor microbiomes offer opportunities to develop novel processes for production of commodity chemicals out of a wide diversity of organic residual streams. The uncovered microbial consortia nurture high potential novel biocatalysts. By creating selection pressures one can steer such process with undefined biocatalysts to the job to be done. Recently, it was discovered that application of methanol as an electron donor in Chain Elongation (CE) steers microbiomes to the formation of significant amounts of branched medium chain fatty acids (branched-MCFAs, i.e. isomer). Industrial interest in branched-MCFAs is driven by the need for enhanced chemical performance properties including improved oxidative stability, low melting point and suitable viscosity. The objective of this project is to gain insights in the formation of Branched-MCFAs through biological processes within CE reactor microbiomes. We will investigate this microbiomes for examining key-steering parameters and attempt to understand the competing and desired bioprocesses in the microbiome. This study will integrate microbial composition analysis with continuous operation of reactor microbiomes. Two paths will be followed; negative value supermarket waste streams will be elongated to branched-MCFAs. Secondly, plant and animal derived residual feedstock containing mass branched amino acids functionality, which is maintained while converted, will be used to produce branched-MCFAs. This research will support the development of an economic, renewable and geographically unbound production processes of branched-MCFAs. Flexible microbiological upgrade of low grade biomass residue into commodity chemicals is warranted. The used feedstock are produced by leading Dutch biorefineries that allow rapid implementation. We envision that laboratory discoveries will lead to direct impact from green biotechnology.

The Ganges-Brahmaputra-Meghna (GBM) delta faces rapid, unplanned urbanization driven by rural-urban migration and informal governance. This increases vulnerability to hydro-climatic hazards and socio-ecological challenges, especially in peri-urban zones. Peri-urban livelihoods suffer due to multi-hazard exposure, unstable employment, inadequate infrastructure, limited access to services, and lack of just governance. Using Living Labs in a systems dynamics approach, FLASH addresses the broader scientific question of how to create sustainable, climate-resilient livelihood options for peri-urban populations in Bangladesh’s delta region. The interrelated outcomes offer sustainable and climate-resilient peri-urban livelihood options in the GBM delta, aligning with the Bangladesh Delta Plan 2100.

With an increasing global urbanization, demands on the livelihood of cities are rising swiftly. In the conventional urban growth, biodiversity is often constrained, separation of functions leads to inefficient resource use, impact of climate change becomes extreme and human health is increasingly endangered. Green infrastructure (GI, e.g. green roofs, parks) in cities may simultaneously supply multiple functions that contributes to solve these issues. The challenge is how to accommodate and harmonise these possibly synergising or competing functions of GI in current and future urban landscape. Here, transdisciplinary learning[14] will be used to co-create the planning and design of the multi-functioning of GI in cities. Building from our experiences in Xiamen, Breda and Nieuwegein, we will develop and evaluate such multi-functional designs for these cities. We hypothesize that learning among multiple disciplines and cities are the two keys to unlock the potential of multi-functioning of GI. In this research we aim at operationalizing this learning process via (1) co-creation of a GI planning and evaluation tool, MultiGreen, to stimulate and distil the transdisciplinary learning for multi-functioning of GI and (2) participatory-based application of MultiGreen in selected case cities to facilitate learning among stakeholders so as cities. We start with, but not limited to, integrating three main GI functions: the circular food provision, climate adaptation, and biodiversity restoration; different GI approaches like urban farm, green roofs or wadi are thus considered. Then, a GIS-based building stock model is connected to an agent-based model to analyse the potential of ecological and social-economic benefits for accommodating different GI approaches. At last, a geo-spatial module matching the GI provision of multi-functioning and local demands will be developed and applied via a participatory approach in different case cities. Thus MultiGreen will enable the future designs of multi-functional GI to maximize the livelihood cities.

Hydrogen sulfide (H₂S) is a toxic, corrosive gas often found in industrial emissions. One promising way to remove it is biological desulfurization, where special bacteria convert H₂S into recoverable elemental sulfur under alkaline conditions. This thesis examines a new dual-reactor system that creates polysulfides—intermediate sulfur compounds thought to be crucial in this process. Using pilot- and lab-scale setups, the research shows that polysulfide formation and stability are strongly influenced by sulfide levels, biomass, and pH. Understanding these factors helps balance chemical and biological reactions, leading to more efficient sulfur recovery and improved control of industrial H₂S pollution.