Optimizing first flush diverter for urban stormwater pollution load reduction by most efficiently utilizing first...

Area of Science:

• Environmental Engineering
• Water Resource Management
• Stormwater Management

Background:

• First flush phenomenon in stormwater runoff significantly impacts pollution control.
• Conventional research often focuses on the existence of first flush, not its optimal utilization.
• Effective first flush diverter design is crucial for managing roof runoff pollution.

Purpose of the Study:

• To develop and apply a novel method for optimizing first flush diverter design.
• To shift focus from the first flush phenomenon's existence to its utilization effect.
• To determine optimal design parameters for roof runoff pollution control.

Main Methods:

• Defined key design parameters and performance indicators for first flush diverters.
• Employed continuous simulation to model diverse runoff events and uncertainties.
• Utilized overlapped contour graphs for design optimization based on pollutant load reduction and first flush concentration.
• Introduced pollutant load frequency spectra for daily temporal analysis.

Main Results:

• Annual pollutant load reduction (PLR) was found to be insensitive to the buildup model, simplifying design.
• Optimal design parameters were identified using contour graphs to balance PLR and first flush concentration (MFF).
• Achieved 40% PLR with MFF >1.95 and 70% PLR with MFF = 1.7.
• Pollutant load frequency spectra demonstrated that optimized diverters reduce load more stably with less diverted first flush volume.

Conclusions:

• The proposed method effectively optimizes first flush diverter design for roof runoff pollution control.
• The approach simplifies modeling by reducing sensitivity to buildup parameters.
• Optimized diverters offer stable pollutant load reduction and efficient first flush management.