Dissolved air flotation for AfricaSuperior clarity.Sustainable solutions.

Ex-works equipment cost is driven by flow, materials of construction and the extent of the dosing and control scope. As an indicative planning band, a packaged carbon-steel unit with epoxy lining lands around USD 25,000–60,000 at 5–20 m³/h, USD 60,000–140,000 at 20–60 m³/h, and USD 140,000–350,000 at 60–150 m³/h. Stainless SS304 typically adds 30–50 %, SS316L 60–90 %, duplex more again. Freight, duties and installation are separate. We do not quote a figure before we understand the stream, because a number produced without knowing your TSS, FOG, temperature and discharge target is a number that will change.

Three calculations govern it. First, flotation area = design flow ÷ surface loading rate (5–15 m/h conventional, 15–30 m/h high-rate). Second, air demand from the air-to-solids ratio, normally 0.005–0.06 kg air per kg solids depending on the stream. Third, recycle flow, derived from air demand, saturator pressure and the solubility of air at your design temperature — the step most often done wrong, because solubility falls about 20 % between 20 °C and 32 °C. Our sizing calculator applies the temperature correction automatically.

With correct coagulation and flocculation: 85–98 % of suspended solids, 90–99 % of free and emulsified fats, oils and grease, 40–70 % of total COD where the COD is particulate, and 60–90 % of total phosphorus with an iron or aluminium coagulant. Where COD is largely soluble — a brewery is the classic case — expect 20–40 % only. Flotation cannot remove dissolved organics, and any supplier promising a soluble-COD consent from a DAF alone is misleading you.

Yes, but it must be designed for them. Air solubility in water falls with temperature: about 24.3 mg/L at 20 °C and roughly 19.5 mg/L at 32 °C at atmospheric pressure. A unit sized on 20 °C data and run at 32 °C delivers roughly 20 % less air than intended, and the float turns thin and grey. The correction is straightforward — a larger recycle ratio or a higher saturator pressure — provided it is applied at the design stage rather than discovered at commissioning.

A clarifier settles solids denser than water using gravity, at 0.5–1.5 m/h. A DAF floats solids by attaching air bubbles, at 5–30 m/h. The practical consequences: a DAF occupies ten to twenty times less plan area for the same flow, produces a thicker sludge (3–6 % dry solids versus 0.5–2 %), handles fats and low-density solids that will never settle, and recovers within minutes of a power interruption. A clarifier uses far less energy and no chemicals in the simplest cases. Full comparison →

We deliver CIF to any African port and support commissioning on site. Installation itself is normally executed by a local contractor to our drawings, which keeps cost and mobilisation time down. We supply the general arrangement, P&ID, foundation loading, electrical schedule and commissioning procedure, and attend start-up.