From 17–21 November 2024, Brisbane became a hub for innovation and collaboration as 330 delegates gathered for the IWA Nutrient Removal and Recovery Specialist Conference.
In this reflection, WaterRA Research Manager Vincent Bianchini shares key takeaways from the event, which spotlighted groundbreaking solutions to tackle nutrient pollution, advance the circular economy, and address greenhouse gas (GHG) emissions in wastewater management—all critical steps toward achieving sustainability goals in the water sector.
The race to protect ecosystems in a changing climate
Robert Speed’s (Great Barrier Reef Foundation) opening keynote used the Great Barrier Reef as a striking example of the urgency required in nutrient management and climate action. With nutrient pollution contributing to coral bleaching and outbreaks of crown-of-thorns starfish, Speed called for bold interventions, including market-based solutions like nutrient risk insurance and reef credit schemes.
Cameron Jackson (Urban Utilities) extended this message by emphasising integrated strategies. While advanced wastewater treatment technologies are vital, they alone cannot mitigate the broader issue of nutrient pollution. Holistic, catchment-based approaches—such as sediment monitoring and streambank rehabilitation—are essential to improving water quality and ecosystem resilience.
Rethinking nutrient management through innovation
Innovation in nutrient recovery emerged as a conference highlight. Anna Soares (Cranfield University) introduced “nutrient neutrality,” where decentralised systems and algae-based technologies offer promising solutions for overloaded environments. Cutting-edge methods, such as synthetic zeolites for ammonia recovery and microorganisms for struvite harvesting, represent significant advancements in nutrient recycling.
In an unexpected twist, Emma Baxter Brewster (University of Southern Queensland) identified adult diapers as a surprising yet impactful nutrient source. By diverting them from landfill, wastewater operators could recover nitrogen and phosphorus comparable to food organics and garden organics (FOGO) streams, advancing circular economy objectives.
Polyhydroxyalkanoates (PHAs) also gained attention for their potential to turn wastewater streams into sustainable feedstocks for biopolymer production, illustrating the untapped value in resource recovery.
Greenhouse gas emissions, particularly nitrous oxide (N₂O) and methane, were a key focus of the conference. Advanced modelling techniques highlighted practical N₂O mitigation strategies such as adjusting dissolved oxygen levels, adding chemical oxygen demand (COD) and increasing alkalinity (Kristian Sahlstedt, HSY; Xavier Flores Alsina, Delft University of Technology). Trials of these mitigation strategies, conducted alongside full-scale monitoring, demonstrated promising results in reducing emissions while maintaining treatment performance.
Methane emissions also emerged as a focus, with Sarah Aucote (SA Water) presenting innovative strategies to mitigate emissions from sludge lagoons, achieving 40% emissions reduction via nitrate addition. These findings highlight the potential of targeted interventions to address methane emissions, a major contributor to GHG emissions from wastewater treatment.
However, as Kaili Li (University of Queensland) and others noted, N₂O emissions remain a significant challenge for the wastewater sector due to the complex and variable processes driving their production. Developing a standardised approach to monitor and quantify N₂O emissions is essential to understand production pathways, generate reliable and comparable data, enhance process models and identify effective mitigation strategies.
Game-changing advancements in process intensification
Innovations in process intensification are redefining what’s possible within existing infrastructure. Membrane aerated biofilm reactors (MABR) stood out as a transformative technology for dense urban areas, delivering low-energy, small-footprint solutions that improve nutrient removal while cutting aeration energy use by up to 20% (Yangshuo Gu, PUB). It was also shown that MABR has lower N₂O production than the activated sludge process, but that operational conditions may be more important than the process itself for mitigating N₂O emissions (Kevan Brian, Watercare).
Pusker Regmi’s (Stantec) keynote on full-scale trials highlighted three critical insights: leveraging existing assets, harnessing unexpected synergies, and embracing open innovation. These strategies emphasise the value of continuous research and collaboration during large-scale implementations.
A united vision for a sustainable future
The conference provided an inspiring snapshot of the water sector’s collective effort to combat nutrient pollution, reduce emissions and rethink resource recovery. It underscored the vital role of innovation and collaboration in overcoming real-world challenges to achieve sustainable outcomes.
Reflecting on the event, Vincent Bianchini said:
“This conference showcased the power of collaboration between industry and academia in addressing wicked problems. It’s clear that reaching our sustainability goals will require both technical ingenuity and strong partnerships.”
As the water sector continues to push boundaries in nutrient recovery and GHG reduction, these discussions serve as a powerful reminder of what can be achieved through dedication, creativity and collaboration.
Special thanks to David Bergmann, incoming CEO of Water Research Australia, for sharing his comprehensive notes and insights, which helped shape this summary.