Calculations
Recommendations
Triangular weirTablet calcium hypochloriteActivated sludge bioreactorGrit chamberSigma rotary distributor for biological filterHead loss in sewer trash racks
Downflow
Upflow
Input data
Flow
Width (b)
Trashrack width (W)
Distance between trashracks (d)
Downflow level (y)
Slope (º)
β - Kirschmer
Output data
Upflow level
Upflow velocity
Energy
Velocity between bars
Head loss
Upflow level at 50%
Upflow velocity at 50%
Velocity between bars at 50%
Upflow energy at 50%
Head loss at 50%
Description
Given the flow, channel geometry, and screen characteristics, this tool calculates the downflow water level if the upflow water level is known, or the upflow water level if the downflow water level is known. This is particularly useful in wastewater systems where trash racks are used to remove solids.
Available Calculation Methods
1. Downflow
Calculates the upflow water level, velocity, and energy, considering the known downflow water level.
Inputs:
| Parameter | Unit | Description |
|---|---|---|
| Flow (Q) | m³/s | Inlet flow |
| Width (b) | m | Width of the channel |
| Trashrack width (W) | m | Thickness of the trashrack |
| Distance between trashracks (d) | m | Spacing between the trashracks |
| Downflow level (y) | m | Water level at downflow |
| Slope (º) | - | Slope angle of the trashrack |
| β - Kirschmer | - | Kirschmer coefficient |
Outputs:
| Parameter | Unit | Description |
|---|---|---|
| Upflow level (ym) | m | Water level at upflow |
| Upflow velocity (Um) | m/s | Flow velocity at upflow |
| Energy (Em) | J | Energy at the upflow |
| Velocity between bars (Ubb) | m/s | Flow velocity between bars |
| Head loss (Hl) | m | Head loss in the system |
2. Upflow
Calculates the downflow water level, velocity, and energy, considering the known upflow water level.
Inputs:
| Parameter | Unit | Description |
|---|---|---|
| Flow (Q) | m³/s | Inlet flow |
| Channel width (b) | m | Width of the channel |
| Trashrack width (W) | m | Thickness of the trashrack |
| Distance between trashracks (d) | m | Spacing between the trashracks |
| Upflow level (ym) | m | Water level at upflow |
| Slope (º) | - | Slope angle of the trashrack |
| β - Kirschmer | - | Kirschmer coefficient |
Outputs:
| Parameter | Unit | Description |
|---|---|---|
| Downflow level (y) | m | Water level at downflow |
| Downflow velocity (U) | m/s | Flow velocity at downflow |
| Energy (E) | J | Energy at the downflow |
| Velocity between bars (Ubb) | m/s | Flow velocity between bars |
| Head loss (Hl) | m | Head loss in the system |
References
- WEF, ASCE, EWRI (2010). Design of municipal wastewater treatment plants. Volume 2: liquid treatment processes. New York, McGraw Hill.