Holistic aeration management trial shows how operational optimisation can deliver rapid emissions and energy savings.
N₂O is a greenhouse gas around 275 times more potent than CO₂, accounting for up to 80% of wastewater treatment plant emissions. In France, N₂O reduction is led by wastewater authorities, driven by national climate targets and the Urban Wastewater Treatment Directive. Controlling these emissions is becoming increasingly important for French utilities as net zero and nutrient removal requirements emerge.
Cobalt Water’s N2ORisk decision-support platform offers a route to achieve this. The platform combines expert process knowledge with machine-learning models to quantify N₂O emissions in real time. The platform also supports operational optimisation to reduce both emissions and energy use.
Trial Reservoirs Initiative supported a trial to evaluate this technology under real-world conditions at Rennes Métropole’s Beaurade wastewater treatment plant. The project brought together Purecontrol (real-time aeration control), Cobalt Water Global (N2ORisk DSS), and Rennes Métropole (end user).
The objective was to validate the combined decision-support and real-time control approach for measuring, monitoring, and mitigating N₂O emissions.
The trial achieved approximately 20% electricity savings and avoided nearly 20 tonnes of CO₂e. By linking operational parameters, including dissolved oxygen levels, to N₂O risk, the system enabled targeted mitigation strategies without infrastructure changes. Following its successful demonstration at Beaurade WWTP, the technology moved to commercial use across four additional sites.
Benefits of Innovation
- Science-based quantification: Cobalt Water’s N2ORisk DSS platform replaced generic emission factors with precise estimates based on site-specific operational data.
- Real-time optimisation: Purecontrol’s AI platform enables dynamic aeration adjustments that reduce energy use while minimising N₂O formation risk.
- Cost effective mitigation: The system identifies low-cost operational strategies that reduce emissions without requiring infrastructural upgrades.
Specialist Services Involved
- Expert support: We provide expert support in trial design, execution and final documentation review to ensure high quality outcomes. This supports trial success for the end-user while serving as a good reference for the technology supplier in similar applications.
- Trial validation: We receive and assess the trial end report from the technology vendor. The Trial Reservoirs specifically addresses key questions that the trial must answer.
- Due diligence: Isle has a robust process for helping stakeholders adopt innovative technologies and ensuring they are fit for purpose.
- Repayable grant funding: Isle facilitates negotiation with technology developers and end users to agree upon the trials’ critical success factors and key performance indicators (KPIs). Loans are then released to the technology developers.
- Zero risk trial: Should a trial not meet its KPIs, there is no obligation for the tech company to pay back the loan. Similarly, there is no obligation for the end user to make a purchase order; the Trial Reservoir assumes the risk.
- Investor introductions: Isle uses its extensive worldwide network to provide introductions to potential investors.
Outcomes
The trial at Beaurade was a success, delivering significant measurable outcomes, including:
- Energy savings: Approximately 20% reduction in electricity use.
- CO₂e reduction: Nearly 20 tonnes of CO₂ equivalent avoided during the trial.
- Operational optimisation for N₂O reduction: Real-time N₂O monitoring and automated aeration optimisation linked operating conditions to emissions risk. This allowed operators to implement low-cost adjustments that reduce emissions without new infrastructure.
These results demonstrated that systematic N₂O reduction is achievable through intelligent process optimisation, offering a replicable model for other water utilities facing similar decarbonisation targets.
Key contact:
For enquiries and further information, please contact Dr Jo Burgess, Head of Trial Reservoirs Initiative at [email protected].