Nazanin Moradi earns PhD for research on sustainable waste treatment using ozone-based processes

“I studied how we can sustainably manage digestate by using advanced oxidation processes, specifically ozone treatment, to remove harmful contaminants,” she explains. Organic waste is often broken down through anaerobic digestion (AD), a process that creates renewable energy and a nutrient-rich by-product called digestate. However, digestate often contains contaminants that limit its safe reuse. Moradi’s research focuses on improving AD’s sustainability by removing these contaminants, which could enable the safe return of waste to the environment as a valuable resource.

Using ozone as a post-AD treatment process could lead to cleaner and safer discharge of digestate to the environment. Moradi also developed a model to predict ozone usage and tested an advanced UV-ozone system, demonstrating how ozone can enhance digestate treatment while lowering costs and energy use. Her research supports a circular economy by transforming waste into a safe, reusable product, reducing the environmental impact of waste processing.

A memorable milestone for Moradi came during her first field trial with a pilot-scale treatment system. After extensive lab work and numerous adjustments, seeing the system remove contaminants from actual digestate was a turning point, confirming that her approach could be applied on a larger, practical scale. This success showed that her theoretical research had real-world potential, reinforcing her commitment to sustainable waste solutions.

One of the main challenges in her PhD was handling the complexities—and the smell—of digestate. Digestate is highly variable in composition, which makes it a challenging material to work with. Ensuring her process could consistently remove contaminants required rigorous trial and error, pushing Moradi to refine her approach for reliable results. The process taught her resilience and adaptability, crucial qualities for tackling environmental challenges.

Moradi’s vision is to see ozone treatment systems widely adopted for sustainable waste processing, installed alongside anaerobic digesters worldwide. This could transform how organic waste is treated, helping prevent contaminants from entering ecosystems and ensuring that organic waste is safely returned to the environment.

In the coming years, Moradi hopes to advance her work in sustainable waste management by focusing on scaling and refining ozone-based treatments. This path, she believes, could help turn waste into a renewable resource on a global scale.

Reflecting on her journey, Moradi advises her beginner self to “never give up, even when progress seems invisible.” She emphasizes that setbacks and slow progress are essential parts of PhD research and contribute to meaningful breakthroughs, even if they’re not immediately visible. Her research embodies the persistence and innovation needed to make waste management safer and more sustainable for all.