Operational decision support system for large combined sewage systems: Lisbon/Tagus estuary case study

Area of Science:

• Environmental Engineering
• Water Resource Management
• Computational Fluid Dynamics

Background:

• Managing combined sewage discharges into coastal waters is complex, especially in urban areas with recreational activities.
• Effective impact assessment requires sophisticated hydrodynamic and water quality models, often needing expert operation.
• Decision support tools are crucial for simulating discharge impacts and devising mitigation strategies.

Purpose of the Study:

• To develop an operational decision support system (ODSS) methodology for non-expert wastewater utility staff.
• To enable user-friendly scenario analysis of combined sewage discharge impacts using computational fluid dynamics (CFD).
• To apply and validate the ODSS for the Lisbon combined sewage system and Tagus estuary.

Main Methods:

• Development of an Operational Decision Support System (ODSS) methodology.
• Integration of computational fluid dynamics (CFD) simulations for scenario analysis.
• Application and validation of the ODSS to the combined sewage system of Lisbon, Portugal.

Main Results:

• The ODSS enables non-expert staff to conduct user-friendly scenario analyses of sewage discharge impacts.
• Simulations were performed for a discharge event during scheduled maintenance in Lisbon's sewage infrastructure.
• The system was successfully applied and validated for the Tagus estuary receiving waters.

Conclusions:

• The ODSS enhances the decision-making capabilities of wastewater utility staff without specialized modeling expertise.
• It improves understanding of the utility's role in mitigating negative impacts of sewage discharges.
• The methodology facilitates better management of combined sewage discharges into sensitive coastal environments.