Modelling faecal microbe dynamics within stormwater constructed wetlands.

Area of Science:

• Environmental Engineering
• Water Quality Management
• Microbial Ecology

Background:

• Faecal microbe modelling in wetlands is vital but challenging due to unpredictable storm events.
• Accurate prediction of microbial removal is essential for effective stormwater management and public health.

Purpose of the Study:

• To develop and test a coupled hydrodynamic and microorganism model for predicting long-term faecal microbial removal in stormwater constructed wetlands.
• To assess the model's performance using a two-year dataset from a real-world stormwater wetland.

Main Methods:

• A coupled hydrodynamic and microorganism model simulating *Escherichia coli* (E. coli) fate and transport was developed.
• The model incorporated advection-dispersion, sedimentation, resuspension, and die-off influenced by temperature and UV.
• Model calibration involved site-specific data and literature values, with the dark die-off rate as the primary adjusted parameter.

Main Results:

• The hydrodynamic model achieved a Nash-Sutcliffe Efficiency (E) of 0.86 over two years.
• The E. coli model achieved an overall E of 0.37, with performance varying across monitored events (E <0 to 0.8).
• Sensitivity analyses highlighted the critical importance of high-quality stormwater input data and accurate die-off rate estimation.

Conclusions:

• The developed model can aid in designing and optimizing stormwater constructed wetlands for enhanced faecal microbial removal.
• The findings emphasize the need for precise data collection and parameter estimation for reliable microbial removal modelling.
• This tool supports better vegetation management and facilitates real-time decision-making in wetland operations.