Dissolved Air Flotation Sizing

Dissolved Air Flotation Sizing and Calculation:

1.
Contacting Zone of Dissolved Air Flotation:

1.1
Surface Area Ac:
A_c=(Q+Q_r)/(3600*V_c)
A_c: Surface Area of Contacting Zone, in m²
Q: Designed Capacity for Dissolved Air Flotation, in m³/h
Q_r: Quantity/Volume of Air-saturated Water, in m³/h
V_c: Average Water Flow Velocity, generally, 10-20mm/s

1.2
Length L:
L=A_c/B_c
L: Length of Contacting Zone, in m
B_c: Width of Contacting Zone, in m

1.3
Water Depth above Weir H₂:
H₂=B_c
H₂: Water Depth above Weir, in m

1.4
Contacting Time T_c:
T_c=(H₁-H₂)/V_c
T_c: Contacting Time of Contacting Zone, T_c>60s
H₁: Water Depth of Air Flotation Separation Zone, generally, 1.8-2.2m

2.
Air Flotation Separation Zone:

2.1
Surface Area As:
A_c=(Q+Q_r)/(3600*V_s)
A_s: Surface Area of Separation Zone, in m²
V_s: Average Water Down-flow Velocity, generally, 1-1.5mm/s

2.2
Length L_s:
L_s=A_s/B_s
L_s: Length of Separation Zone, in m
B_s: Width of Separation Zone, in m

2.3
Water Depth of Dissolved Air Flotation H:
H=V_s*t
H: Water Depth of Dissolved Air Flotation, in m
t: HRT (hydraulic retention time) of Separation Zone, generally, 10-20 minutes

2.4
Volume of Dissolved Air Flotation W:
W=(A_c+A_s)*H
W: Volume of Dissolved Air Flotation, in m³

2.5
Verification of Total HRT T:
T=60*W/(Q+Q_r)
T: Total HRT, in minute

3.
Air Saturator/Air Dissolving Tank:

Air Saturator Diameter D:
D=[4*Q_r/(π*I)]^(1/2)
D: Air Saturator Diameter, in m
I: Hydraulic Load, generally 80-150m³/(m²·h)

To the design and calculation of Dissolved Air Flotation, please click to read: Dissolved Air Flotation Design Calculation.