How it works
- the idea — A particle in an open tank must fall the whole water depth to be captured. Fill the tank with inclined plates 50 mm apart and it only has to fall 50 mm. The settling distance collapses while the flow path stays long — that is the entire trick.
- projected area — What counts is not the plate area but its horizontal projection, plate area times cos θ. Sixty plates of 2 × 1.5 m at 55° give roughly 100 m² of settling area inside a tank whose floor is under 10 m². A tenfold area multiplier in the same civil works.
- sludge return — Solids land on the plate and slide back down against the upward flow. This only works above about 45°. Below that the sludge stalls, the passages blind over, and performance falls off a cliff — drag the angle down and watch the flag.
- laminar flow — The plate passages must stay laminar. Above roughly Re 500 the flow becomes unsteady, settled solids are re-entrained, and the extra area buys nothing. This is what limits how hard you can push a lamella pack.
- what governs it — Overflow rate on the projected area is the sizing number, and it should be gentler than an open clarifier because the passages are short and unforgiving. Then check angle for sludge return and Reynolds for stability. Get all three or the pack blinds.
Design parameters
The panel opposite runs the same correlations as the C-330 design sheet, so the animation and the calculator cannot disagree. Drag any of them and the picture responds.
- Feed flow — m³/h
- Influent SS — mg/L
- Number of plates — off
- Plate length — m
- Plate width — m
- Plate angle — °
Open the full C-330 design sheet for the governing equations, the accepted design envelopes and the worked calculation.