**Context**

Water resources recovery facilities (WRRFs) are integral components of urban water management, responsible for complex and partially observable processes that require monitoring and control to ensure stable, safe, and efficient operation. Modelling these facilities' biological, chemical, and physical processes is valuable for gaining process understanding, simulating and testing control strategies, and predicting future behaviour under changing conditions. While engineers have traditionally favoured mechanistic modelling approaches, data-driven methods are gaining increasing interest due to advancements in sensor technologies, enabling widespread data collection and real-time monitoring. Hybrid modelling (HM) offers a solution that combines the strengths of both mechanical and data-driven models. By integrating mechanical models, which retain process knowledge and extrapolation capabilities, with data-driven models, which enhance predictive capabilities by uncovering unknown relationships. HM aims to optimize the modelling process and overcome the limitations of individual approaches.

We are the international water association's ([IWA](https://iwa-network.org/)) working group on hybrid modelling in water and wastewater treatment. If you are an IWA member you find us on [IWAconnectplus](https://www.iwaconnectplus.org/group/feeds?CommunityKey=a0M4K000004QCWGUA4) or otherwise on [LinkedIn](https://www.linkedin.com/company/hybrid-modelling-working-group/). We are dedicated to explore the effectiveness of different modelling approaches in the field of water and wastewater treatment. Mechanistic models, pure data-driven models, and hybrid models are all utilized in this domain. We are intrigued to determine which model type is most suitable for practical wastewater treatment applications. To gather exceptional modellers and foster innovation, we are hosting this competition. We encourage you to employ your diverse knowledge and skills to compete for the prize!

**Acknowledgements**
[Darrow Project](https://www.wastewater.ai/)
[International Water Association (IWA)](https://iwa-network.org/)