Packaged DAF units, 2 to 150 m³/h
The workhorse of industrial pretreatment: a complete flotation plant on one frame, pre-piped and pre-wired, needing only a level slab, a power supply and pipework.
A packaged DAF unit is a factory-assembled, skid-mounted dissolved air flotation plant covering 2 to 150 m³/h. It carries the flotation cell, surface skimmer, saturator, recycle pump, air compressor, flocculation stage, dosing skid and control panel on a single frame. Because it needs no civil structure beyond a level reinforced slab, typical installation takes three to seven days against three to five months for a civil-built cell. Surface loading is 5–12 m/h, installed power 2–35 kW depending on size, and delivery is by flatbed or open-top container.
Capacity table
| Flow m³/h | Flotation area m² | Skid L × W × H | Dry weight | Operating weight | Installed power |
|---|---|---|---|---|---|
| 2 – 5 | 0.4 – 0.7 | 2.2 × 1.2 × 2.0 m | 0.6 t | 2.0 t | 2.2 kW |
| 5 – 10 | 0.7 – 1.5 | 2.8 × 1.4 × 2.1 m | 0.9 t | 3.2 t | 3.0 kW |
| 10 – 20 | 1.5 – 2.8 | 3.5 × 1.6 × 2.2 m | 1.4 t | 5.0 t | 5.5 kW |
| 20 – 40 | 2.8 – 5.5 | 4.6 × 1.9 × 2.4 m | 2.3 t | 8.5 t | 9.0 kW |
| 40 – 70 | 5.5 – 9.5 | 6.0 × 2.2 × 2.6 m | 3.6 t | 14 t | 15 kW |
| 70 – 110 | 9.5 – 15 | 7.8 × 2.4 × 2.8 m | 5.2 t | 22 t | 22 kW |
| 110 – 150 | 15 – 20 | 9.5 × 2.6 × 3.0 m | 7.0 t | 31 t | 30 kW |
Scope of supply
- Rectangular flotation cell with adjustable effluent weir, sludge hopper and drain
- Variable-speed chain-and-flight or blade skimmer, with bottom scraper where required
- Saturator vessel, 4–6 bar, with level control, sight glass, safety relief and air injection
- Multistage recycle pump sized on calculated recycle flow at working pressure
- Oil-free air compressor with receiver and pressure regulation
- Release nozzles or needle valves, accessible for cleaning without draining the cell
- Two- or three-stage flocculation chambers with variable-speed paddles, or inline static mixing
- Coagulant and polymer dosing pumps with calibration columns; polymer make-up unit where powder polymer is used
- pH correction dosing where the stream requires it
- PLC control panel with HMI, level and pressure instrumentation, dry-run and high-level protection
- General arrangement, P&ID, foundation loading drawing, electrical schedule, O&M manual, commissioning procedure
What the site must provide
| Item | Requirement | Common mistake |
|---|---|---|
| Foundation | Level reinforced slab, 150–250 mm, designed for operating weight plus 25 % | Slab sized on dry weight |
| Balance tank | 6–12 h HRT, mixed, with level control | Omitted entirely — the single most common cause of poor performance |
| Screening | 1–3 mm fine screen upstream | Coarse screen only; fines wreck the recycle pump |
| Power | 3-phase, per installed power; stable supply or generator backup | No allowance for compressor inrush |
| Water | Clean water for polymer make-up and wash-down | Polymer made up with raw effluent |
| Sludge route | Holding tank, minimum 2 days, then dewatering or tanker | Assuming the DAF sludge hopper is storage |
| Access | 1 m clear on three sides, 1.5 m on the skimmer drive side | Unit boxed in against a wall |
| Drainage | Bunded chemical area with separate containment | Chemicals stored on open ground |
Indicative price bands
Ex-works equipment only, complete with dosing skid and controls, carbon steel with epoxy lining. These are planning figures for budget purposes, not quotations.
| Flow | Carbon steel + epoxy | SS304 | SS316L |
|---|---|---|---|
| 2 – 5 m³/h | USD 18,000 – 32,000 | +35 % | +70 % |
| 5 – 20 m³/h | USD 25,000 – 60,000 | +35 % | +70 % |
| 20 – 60 m³/h | USD 60,000 – 140,000 | +30 % | +65 % |
| 60 – 150 m³/h | USD 140,000 – 350,000 | +30 % | +60 % |
Frequently asked questions
How long does it take to install a packaged DAF?
Three to seven days on a prepared slab for a single-piece skid: set down, connect inlet, outlet, sludge and drain, terminate power, fill and level. Multi-section units in the 60–150 m³/h range take one to two weeks to assemble. Commissioning — leak test, saturator pressurisation, jar-test confirmation, dose optimisation and operator training — adds a further three to five days.
Do I need a balance tank before a packaged DAF?
In almost every industrial application, yes. A DAF is a steady-state device: it wants constant flow, constant solids and stable pH. Industrial effluent is none of those things. Six to twelve hours of mixed balancing turns a difficult stream into an easy one, and it is by a wide margin the cheapest performance improvement available. Omitting it to save capital is the most expensive decision made in effluent plant procurement.
Can a packaged DAF be moved later?
Yes — that is one of its advantages. A skid unit can be drained, disconnected and relocated in a few days, which suits leased premises, phased factory expansion and businesses that expect to move. Civil-built cells cannot. Factor the operating weight into any crane or transport planning.
What maintenance does a packaged DAF need?
Daily: check float thickness and effluent clarity, confirm chemical levels, log saturator pressure. Weekly: clean release nozzles, check skimmer flights and chain tension, calibrate dosing pumps. Quarterly: inspect the saturator internals, service the compressor, check the recycle pump. Annually: drain and inspect the cell, check coatings and weld lines. Budget 0.5–1 operator-hour per day for a mid-sized unit.