Methodology
53
• Purification yield
The purification yield is given by the following formula:
R=
í µí±ª í µí² −í µí±ª í µí²
í µí±ª í µí²
×100
With :
Ci : Nitrogen concentration at plant inlet.
Cf : Nitrogen concentration at plant outlet ([A]=30mg/l)
The results of the calculations are summarized in Table 18 (Chapter 3).
6.5. Sizing of wastewater treatment plant structures
6.5.1. Pre-treatment
6.5.1.1.Receiving structure
The intake structure will receive the entire flow conveyed by the pipe and will be
equipped with the following accessories:
Weir for all flows in excess of the maximum flow of 1117,389 m
3 /h to be
admitted in wet weather.
By-pass flow measurement device with ultrasonic probe on overflow blade.
Stainless steel manual screen: of 316 l and 80 mm spacing, for by-passed
effluent.
6.5.1.2. Screen sizing
Bar screens play a very important role in protecting electromechanical equipment and
reducing the risk of clogging pipes installed in the treatment plant. They are grids that collect
the bulky waste carried along by the water flowing through the sewage pipes. (Mzyene &
Ouali, 2020).
6.5.1.2.1. Coarse screen
This screen is designed to protect the pumps from any large bodies that may be
carried by the collector, and is spaced between 10 and 50 mm apart. The rejects
from the screen are removed manually using a rake.
The following KIRSCHMER formula is used to calculate the screen width:
W =
í µí±º×í µí²í µí²í µí² í µí¼¶
í µí±¯ í µí²í µí²í µí² ×í µí¼¹(í µí¿−í µí¼·)
With :
W : scren width (m).
53
• Purification yield
The purification yield is given by the following formula:
R=
í µí±ª í µí² −í µí±ª í µí²
í µí±ª í µí²
×100
With :
Ci : Nitrogen concentration at plant inlet.
Cf : Nitrogen concentration at plant outlet ([A]=30mg/l)
The results of the calculations are summarized in Table 18 (Chapter 3).
6.5. Sizing of wastewater treatment plant structures
6.5.1. Pre-treatment
6.5.1.1.Receiving structure
The intake structure will receive the entire flow conveyed by the pipe and will be
equipped with the following accessories:
Weir for all flows in excess of the maximum flow of 1117,389 m
3 /h to be
admitted in wet weather.
By-pass flow measurement device with ultrasonic probe on overflow blade.
Stainless steel manual screen: of 316 l and 80 mm spacing, for by-passed
effluent.
6.5.1.2. Screen sizing
Bar screens play a very important role in protecting electromechanical equipment and
reducing the risk of clogging pipes installed in the treatment plant. They are grids that collect
the bulky waste carried along by the water flowing through the sewage pipes. (Mzyene &
Ouali, 2020).
6.5.1.2.1. Coarse screen
This screen is designed to protect the pumps from any large bodies that may be
carried by the collector, and is spaced between 10 and 50 mm apart. The rejects
from the screen are removed manually using a rake.
The following KIRSCHMER formula is used to calculate the screen width:
W =
í µí±º×í µí²í µí²í µí² í µí¼¶
í µí±¯ í µí²í µí²í µí² ×í µí¼¹(í µí¿−í µí¼·)
With :
W : scren width (m).