How the calculation works
- Projected settling area = design flow ÷ surface loading. 50 m³/h at 0.8 m/h needs 62.5 m².
- Projected area per plate = plate length × plate width × cos(plate angle). An inclined plate counts with its horizontal projection (Hazen’s surface loading principle).
- Number of plates = required area ÷ (projected area per plate × usable share), rounded up.
- Pack length = number of plates × plate spacing ÷ sin(plate angle) + plate length × cos(plate angle).
Typical design values
| Parameter | Typical range |
|---|---|
| Surface loading on the projected area | 0.5–1.0 m/h for flocculated solids; up to 1.5 m/h for mineral solids |
| Plate angle | 55–60° so that the sludge slides down |
| Plate spacing | 50–80 mm; wider for sludge that tends to stick |
| Usable share of the plate area | 75–85 % |
Limits of this calculator
The surface loading has to come from a settling test or from experience with the same wastewater; it decides the result. The calculator does not size the flocculation stage, the inlet distribution or the sludge hopper. Our lamella clarifiers are designed from your flow, solids load and jar test data.
Frequently asked questions
How do you calculate the area of a lamella clarifier?
Divide the design flow by the permitted surface loading. The result is the projected plate area the clarifier has to provide.
Why are the plates inclined at 55 to 60 degrees?
At this angle the settled sludge slides down the plates by itself while the projected area is still large. Flatter plates give more area but the sludge stays on them.
How much space does a lamella clarifier save?
A plate pack provides its settling area on roughly one tenth to one fifth of the floor space of a conventional settling tank with the same surface loading.