The Power of Wastewater

Researcher’s Chronicle | Francisca Braga,  originally from Braga, Portugal, is currently living in Aarhus, Denmark. She is a PhD student in an industrial setting in collaboration with Skanderborg Forsyning, DTU, and VIA University College. Her doctoral research focuses on demystifying the water-energy nexus by using wastewater for heat recovery and other forms of energy. In addition, she serves as the Secretary of Young Water Professionals Denmark.

Have you ever considered how wastewater could help combat climate change and reduce the energy consumption of wastewater treatment plants?

Wastewater treatment plants (WWTPs) have a direct impact on energy, water, and the climate. They are responsible for approximately 3% of global energy use, making their efficient management crucial for sustainable development and for mitigating environmental impacts.

Wastewater—coming from residential buildings, industrial processes, and commercial activities—often contains an overlooked resource: thermal energy. This energy is a byproduct of several factors, such as heating, cooling, and chemical reactions.

By harnessing the latent thermal energy in wastewater, we could not only reduce energy consumption but also effectively mitigate greenhouse gas emissions, creating a more sustainable future.

Advanced wastewater heat recovery systems, including heat exchangers and heat pumps, can be used to capture this energy. When strategically implemented, these technologies not only maximize the use of wastewater's thermal energy but also significantly contribute to energy efficiency and cost savings.

By integrating these innovative solutions into wastewater management practices, we have the potential to transform what was once considered waste into a valuable resource.

The primary objective of my PhD project is to develop and assess the feasibility and effectiveness of wastewater heat recovery systems tailored for district heating in the Scandinavian region. The research focuses on the development and testing of mathematical models at two distinct sites: Skovby (a small WWTP operated by Skanderborg Forsyning) and Døjsøvej (the main WWTP in Skanderborg). The project combines mathematical and engineering models with collected data to evaluate the potential for heat recovery.

This PhD project is innovative in the field of water and energy, by evaluating and optimizing wastewater heat recovery, offering a blueprint for a more sustainable energy future.

The pressing need to address the significant energy demands and greenhouse gas emissions associated with wastewater treatment highlights the opportunity and importance of this research.

References

Nakkasunchi, S. et al 2021. A review of energy optimization modelling tools for the decarbonisation of wastewater treatment plants. Journal of Cleaner Production. 279, 123811.