C-320Dissolved Air Flotation

How it works

1. Why flotation — Gravity settling stalls when the solids are barely denser than water — algae, oil and grease, light chemical flocs. Watch: with no air, the particles drift the length of the cell and leave with the clarified water. That is carryover, and it is the failure a clarifier cannot design its way out of.
2. Saturation & release — A slipstream of clarified effluent is pumped to the saturator and held against compressed air. Solubility follows Henry's law — proportional to absolute pressure, falling as the water warms. Releasing that stream through nozzles at the cell floor drops it to atmospheric, and the excess air leaves solution as microbubbles 10–100 µm across.
3. Contact zone — attachment — Feed and white water rise together through the narrow contact zone for one to two minutes. Bubbles collide with flocs and adhere. Attachment depends on floc size and surface charge, which is why upstream coagulation is not optional — bare colloids will not hold a bubble.
4. Separation & float — Over the baffle, the aggregates now rise faster than the downward hydraulic velocity and surface as a float layer at 2–5 % dry solids. A skimmer moves it to the beach. Clarified water leaves at the floor; the few heavy particles that never attached fall out as bottom sludge.
5. What governs the design — The binding constraint is the air-to-solids ratio — air made available per unit mass of solids. Push the recycle ratio or saturator pressure up and the bubble cloud thickens; raise the influent SS and the same air has more work to do. Whichever check turns amber first is the one sizing your cell.
6. The conventional cell — An open flotation tank loaded at 8 to 15 m/h. The float blanket forms across the whole surface and is skimmed off. It is the long-standing municipal arrangement for algae, colour and low-density floc, and it is forgiving — but at those loadings it needs a lot of area.

Design parameters

The panel opposite runs the same correlations as the C-320 design sheet, so the animation and the calculator cannot disagree. Every parameter below is live — drag one and the picture responds.

Open the full C-320 design sheet for the other seven inputs, all twenty-nine results with their envelopes, the seven equations printed beside the numbers they produce, and a calculation record you can export and put in a design file.