A 40ft containerised dissolved-air-flotation system engineered for industrial wastewater carrying dissolved heavy metals — lead, zinc, copper and nickel. A sulfide-precipitation stage ahead of the DAF converts dissolved metals into insoluble sulfides that float out cleanly, taking treated effluent below typical industrial discharge limits.
Built around the proven 10 m³/h DAF platform, with the reaction chemistry, online metals monitoring and sludge stabilisation that a metals-bearing stream demands — all factory-tested inside one container.
Turn dissolved metals into a floatable solid, then skim it off
Dissolved metals will not settle or float on their own. The system doses a controlled amount of sulfide (NaHS or Na&sub2;S) at pH 8.5–9.5, where dissolved lead, zinc, copper and nickel form highly insoluble metal sulfides. A short reaction stage completes precipitation; the DAF then floats the fine sulfide precipitate out with the micro-bubble blanket, and the metal-laden sludge is stabilised for compliant disposal.
NaHS / Na&sub2;S dosed 0–50 mg/L under ORP control to drive precipitation.
~10 min retention in an SS 316L reaction tank to complete metal-sulfide formation.
Micro-bubbles float the fine precipitate; surface skimmer removes the float.
Cement mixing of metal-laden sludge for safe landfill disposal.
| Metal | Removal (sulfide precipitation + DAF) |
|---|---|
| Lead (Pb) | >99% |
| Copper (Cu) | >99% |
| Zinc (Zn) | >98% |
| Nickel (Ni) | >95% |
The items beyond a standard DAF that define performance — headline only
| Item | Headline Spec | Purpose |
|---|---|---|
| Sulfide dosing system | NaHS / Na&sub2;S, 0–50 mg/L | Precipitate metals as insoluble sulfides |
| Reaction tank | ~0.5 m³, ~10 min HRT, SS 316L | Complete metal-sulfide precipitation |
| Heavy-metals analyser | Online colorimetric / ICP (Pb, Zn, Cu, Ni) | Inlet/outlet compliance monitoring |
| Enhanced pH controller | Dual-range 0–14 pH, acid/base dosing | Hold the 8.5–9.5 precipitation window |
| ORP controller | ±1000 mV | Trim sulfide dose to redox potential |
| Sludge stabilisation | Cement mixing drum | Stabilise metal-laden sludge for disposal |
Plus the full 10 m³/h DAF platform: lamella flotation cell, 5.5 bar saturator and compressor, recycle/feed pumps, skimmer and scraper, instrumentation and SCADA. The complete itemised BOM, P&ID and FAT pack are issued during detailed design.
Tell us the metals, the concentrations and your discharge consent — we will confirm the chemistry, size the container and ship a factory-tested system that makes consent.
Explore closely-related industrial and DAF guides
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Select the regulatory standard for your country — it sets which parameters we need for a compliance-aware process assessment.
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