Methodology
49
Dry weather peak flow ( í µí° í µí±«í µí²í µí² )
Calculating peak flow is important to ensure that wastewater treatment systems
are able to handle seasonal fluctuations and variations in flow. It is given by the
following formula:
í µí° í µí±«í µí²í µí² = Cp × (í µí±¸ í µí²í µí²í µí²í µí².í µí² )
With:
Cp : The peak coefficient given by the following formula :
CP = 1,5+ (
2,5
√í µí± í µí±í µí±£í µí±í µí±.ℎ
)
If : í µí° í µí°í µí°¯í µí°í µí°«.í µí°¡ ≥ 3 l/S
CP = 3
If : í µí° í µí°í µí°¯í µí°í µí°«.í µí°¡ < 3 l/S
Rainy weather peak flow (í µí±¸ í µí±¹í µí²í µí² )
In order to avoid hydraulic overloading of the storm basin located upstream of the plant
during rainfall, the storm basin is sized for a maximum flow corresponding to(í µí±¸ í µí±¹í µí²í µí² ). Which
represents the flow of wastewater going to the plant in rainy weather. It is calculated using the
following formula:
í µí±¸ í µí±¹í µí²í µí² = í µí° í µí±«í µí²í µí² + α í µí° í µí±«í µí²í µí²
With :
í µí° í µí±«í µí²í µí² :Dry weather peak flow.
α : Coefficient of dilution taken in general equal to 2.
Therefor:
í µí± í µí± í µí±¤í µí± = Q í µí°·í µí±¤í µí± + α Q í µí°·í µí±¤í µí± = (1+ α) Q í µí°·í µí±¤í µí±
í µí± í µí± í µí±¤í µí± = (1+2) Q í µí°·í µí±¤í µí± = 3Q í µí°·í µí±¤í µí±
Maximum flow entering the WWTP (Qmax)
The maximum flow entering the WWTP is generally taken to be equal to 2 × the
average hourly flow:
í µí° í µí²í µí²í µí² =2 ×í µí±¸ í µí²í µí²í µí²í µí².í µí²
49
Dry weather peak flow ( í µí° í µí±«í µí²í µí² )
Calculating peak flow is important to ensure that wastewater treatment systems
are able to handle seasonal fluctuations and variations in flow. It is given by the
following formula:
í µí° í µí±«í µí²í µí² = Cp × (í µí±¸ í µí²í µí²í µí²í µí².í µí² )
With:
Cp : The peak coefficient given by the following formula :
CP = 1,5+ (
2,5
√í µí± í µí±í µí±£í µí±í µí±.ℎ
)
If : í µí° í µí°í µí°¯í µí°í µí°«.í µí°¡ ≥ 3 l/S
CP = 3
If : í µí° í µí°í µí°¯í µí°í µí°«.í µí°¡ < 3 l/S
Rainy weather peak flow (í µí±¸ í µí±¹í µí²í µí² )
In order to avoid hydraulic overloading of the storm basin located upstream of the plant
during rainfall, the storm basin is sized for a maximum flow corresponding to(í µí±¸ í µí±¹í µí²í µí² ). Which
represents the flow of wastewater going to the plant in rainy weather. It is calculated using the
following formula:
í µí±¸ í µí±¹í µí²í µí² = í µí° í µí±«í µí²í µí² + α í µí° í µí±«í µí²í µí²
With :
í µí° í µí±«í µí²í µí² :Dry weather peak flow.
α : Coefficient of dilution taken in general equal to 2.
Therefor:
í µí± í µí± í µí±¤í µí± = Q í µí°·í µí±¤í µí± + α Q í µí°·í µí±¤í µí± = (1+ α) Q í µí°·í µí±¤í µí±
í µí± í µí± í µí±¤í µí± = (1+2) Q í µí°·í µí±¤í µí± = 3Q í µí°·í µí±¤í µí±
Maximum flow entering the WWTP (Qmax)
The maximum flow entering the WWTP is generally taken to be equal to 2 × the
average hourly flow:
í µí° í µí²í µí²í µí² =2 ×í µí±¸ í µí²í µí²í µí²í µí².í µí²