As water utilities work towards net zero, accurately measuring greenhouse gas emissions has become one of the sector's most significant challenges. While emissions reporting continues to evolve, understanding where emissions occur, why they fluctuate and how they can be reduced remains a complex task for wastewater operators.
This is the challenge that has driven Dr Kaili Li's award-winning research.
The University of Queensland researcher was named the recipient of the 2026 Student Water Prize (sponsored by Guidera O’Connor) at the Australian Water Awards for her project, Understanding and Mitigating Greenhouse Gas Emissions from Wastewater Systems in the Data Era.
Li's research was recognised for combining advanced monitoring and hybrid modelling to improve how greenhouse gas emissions are measured and managed, providing practical, scalable tools to support utilities across Australia and New Zealand.
For Li, the research was inspired by a problem that came directly from industry.
"Wastewater treatment plants provide an essential environmental service, but they can also produce significant greenhouse gas emissions, particularly nitrous oxide and methane," she said.
"Surprisingly, nitrous oxide and methane are much more potent than carbon dioxide. They have a much higher global warming potential, yet their emissions can be highly variable and difficult to measure."
"What inspired me was the opportunity to work on a problem that is both scientifically challenging and directly relevant to the water industry."
As Li's understanding of wastewater systems grew, so did her ambition to help utilities move beyond identifying emissions and towards reducing them.
"As I became more familiar with these emissions and with how wastewater treatment plants operate, I wanted to better understand where these emissions were coming from, why they changed over time, and, most importantly, what utilities could realistically do to reduce them," she said.
Nominations for the 2026-27 awards season are now open. Nominate outstanding organisations, individuals and students here.
Li said one of the biggest barriers to reducing emissions is simply understanding them. Unlike many other operational metrics, greenhouse gas emissions from wastewater treatment systems are constantly changing, making them difficult to quantify.
"The biggest challenge is that greenhouse gas emissions from wastewater treatment systems are not constant or easy to predict. They change significantly between different areas of the treatment plant, at different times of the day, and across different seasons," Li said.
"We call these spatial and temporal variations in emissions. A single measurement, or using standard emission factors, may therefore not provide an accurate picture of a plant's actual emissions.
"It's a little like trying to understand the weather by taking one temperature measurement on one day of the year. That's essentially what the industry currently does. We follow the National Greenhouse and Energy Reporting (NGER) guidelines and report emissions using default emission factors."
Li's research combines continuous full-scale monitoring with data analysis and modelling to capture these variations: "This helps us identify when and where emissions occur, understand the operating conditions that drive them, and distinguish genuine patterns from short-term fluctuations."
"Ultimately, the goal is to turn this complex monitoring data into practical information that plant operators can use in their daily operations," she said.
While many utilities are making progress towards net zero, Li believes the greatest opportunity lies in giving operators the evidence they need to make informed decisions within their own plants.
"I have noticed that the majority of water utilities in Australia are working towards net zero. I want to help utilities move from estimating emissions using general assumptions towards making decisions based on actual plant-level evidence," she said.
By combining long-term monitoring with operational data, her work allows utilities to identify emission hotspots and understand the conditions driving them.
"Through long-term monitoring, we can identify the major emission hotspots and the operating conditions associated with higher emissions," Li said.
"By understanding that, we can test practical mitigation strategies, such as adjusting dissolved oxygen levels, changing how wastewater is distributed through the treatment process, or modifying other operating conditions.
"One of the most important findings from my PhD was that substantial emissions can potentially be reduced simply through operational optimisation, without the need for major new infrastructure."
"However, there isn't a single solution that will work for every treatment plant."
Instead, the research provides a practical framework that utilities can adapt to their own operating environments.
"The broader value of the research is providing utilities with a framework to measure emissions reliably, so they know where to start, how to monitor emissions, how to understand them, and how they can realistically and feasibly reduce them," she said.
For Li, one of the defining moments of her PhD came when the data began revealing patterns that had previously been hidden.
"I began comparing the long-term monitoring data I had collected with the plants' normal operating conditions. I could see that the emissions weren't simply random. There were clear spatial, seasonal and operational patterns, and the emission hotspots actually had fundamental reasons behind them," she said.
The next step was demonstrating that those insights could be translated into measurable improvements.
"I conducted full-scale mitigation trials and was able to show that relatively targeted operational changes could produce measurable reductions in emissions," she said.
"That was a very encouraging moment for me, for everyone working on the project, and for the utilities as well, because it moved the research beyond simply identifying the problem and towards demonstrating practical solutions.
"I realised that monitoring isn't only about producing more accurate emissions inventories. When it's connected with process knowledge and operational data, it can actually become a decision-making tool."
Having spent the past six to seven years working alongside researchers and utilities, Li believes the future of wastewater management extends well beyond emissions reporting.
"What excites me most is that wastewater treatment is increasingly being viewed not only as a way to protect public health and the environment, but also as an important part of the circular economy and the transition to net zero," she said.
"Within the wastewater and water industries, we have many opportunities to recover energy, recover nutrients and recover other valuable resources.
"At the same time, developments in sensors, automation, data analytics and artificial intelligence are allowing us to understand and optimise treatment processes in ways that were not previously possible."
Perhaps most importantly, Li said the collaborative nature of the water sector continues to inspire her.
" won't compare it with other sectors, but from my own experience, the water sector is incredibly collaborative. Utilities aren't competing with one another. We're all working towards a common goal," she said.
We work together towards clear social and environmental outcomes. I think that's what makes this such a rewarding field in which to build a career."
Nominations for the 2026-27 awards season are now open. Nominate outstanding organisations, individuals and students here.