Hannah Feldman after her PhD defence

PhD interview: Optimizing reactor performance in wastewater treatment plants through mathematical modeling

Wednesday 10 Oct 18

At DTU Chemical Engineering we value our PhD students and their research. We interviewed Hannah Feldman about her project “Optimization of energy recovery in an industrial wastewater treatment plant”.

The PhD students at DTU Chemical Engineering are valuable assets. One of them is Hannah Feldman who defended her PhD just recently. Here is what she told us about her project.

What is the essence of your PhD project?
My project focuses on the optimization of energy recovery in an industrial wastewater treatment plant. Industrial wastewater can contain large quantities of organics, which need to be removed from wastewater. A sustainable treatment option is to turn these organics into biogas, which can then be converted to energy. We used mathematical models to describe the biological processes taking place in an anaerobic digester, the reactor type which converts organics into biogas, and subsequently evaluate different scenarios to increase the reactor performance.

What did you discover during your research?
We evaluated different scenarios to increase the reactor performance of the anaerobic digester. One of our results is that we found that a pH decrease has a positive effect on the reactor performance index, where we take into account the profit from energy production as well as the costs of chemicals for pH control.

We also looked into modelling how the different bacteria in an anaerobic digester are placed in granules, and how the precipitation of minerals inside granules impacts this. The bacteria compete for space in the granules with precipitates, and the simulation model that I developed predicted a decrease in bacteria and biogas production over time in the presence of a high mineral content of the wastewater.

What are the possible wider implications of your research for society?
There is a shift in the wastewater sector, where wastewater is seen as a resource for production energy and higher value products. However, experiments to confirm this are expensive and cost a lot of time. Mathematical models can help scientists steer the direction of the experiments, or implement changes directly on full-scale. This can hopefully result in a more efficient shift of wastewater treatment to resource recovery.

What made you choose applying for a PhD position at DTU Chemical Engineering?
While I did my masters in the Netherlands, I had to do an industrial internship. I had decided to do this in Denmark, and came in contact with DTU Chemical Engineering. I already knew I wanted to do a PhD, and enjoyed Denmark. DTU Chemical Engineering had a lot of interesting research topics, which combined experimental work with modelling. All of this convinced me to find a PhD position in the department.

What does the future hold for you?
After the completion of my PhD I decided to start in industry. I am now working as a fermentation scientist in Novozymes. While this is no longer wastewater, I will keep working on process optimization.

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