Emulsified Oil in Battery-Material Effluent: What Ozone Catalytic Oxidation Demulsification Achieves

Across the production chain for new-energy battery materials, wastewater treatment has become a step that decides whether a plant runs at all. Metallurgical and washing wastewater from ternary precursor production, lithium-battery recycling and nickel-cobalt-manganese smelting shows oil pollution with three characteristics that tend to arrive together: high concentration, multiple forms and strong emulsification. Emulsified oil, dispersed oil and suspended solids coexist, oil content is high, water quality fluctuates widely, and the emulsified fraction is the stubborn part.

Why the familiar processes run out of road

Fenton plus flocculation-settling is unstable and re-colorizes easily, it consumes large amounts of chemicals, it generates a lot of sludge, and it carries risks of wastewater re-colorization and gas leakage. Coalescence separation and similar physical methods have limited removal efficiency against high-concentration emulsified oil and struggle to meet standards consistently. SINOKLE's CDOF ozone catalytic oxidation flotation integrated technology pairs ozone catalytic oxidation demulsification with cyclonic flotation, and reaches over 99% oil removal with stable compliance. The mechanism is worth unpacking before looking at the numbers.

What makes emulsified oil so difficult

Oil in wastewater divides by form into two groups. Dispersed oil consists of relatively large droplets with good floatability, and conventional flotation separates it without much trouble. Emulsified oil is different. Under stirring, pumping and surfactant action, oil is dispersed into micron-scale particles that stay suspended and are wrapped in an interfacial film. That film is formed by the oriented arrangement of surfactant molecules, and its strength and stability prevent droplets from coalescing or rising, so conventional coalescence and flotation cannot break through it.

This is the root of why coalescence separation looks powerless against high-concentration emulsified oil. It can intercept the oil that floats up, but it cannot break the oil hidden in the water inside a film.

How CDOF attacks the problem, in three steps

Step one is ozone multi-catalytic oxidation, and its target is the film. After conditioning with a water-quality modifier, wastewater enters the CDOF integrated unit, which builds four catalytic paths: homogeneous catalysis, heterogeneous catalysis, hydrodynamic cavitation catalysis and pressurized catalysis. Working together they convert ozone efficiently into highly active hydroxyl radicals, ·OH. That oxidant attacks and destroys the interfacial film of emulsified oil at the molecular level, liberating the droplets from their emulsified state. The demulsification is physical in effect, not a chemical demulsifier programme; only a trace of water-quality modifier is used, which cuts chemical consumption and secondary-pollution risk substantially.

Step two is capture by ultra-fine nanobubbles. The dissolved-air release system produces nanobubbles below 10 μm in diameter. Compared with conventional bubbles they are smaller, far more numerous per unit volume and much larger in specific surface area, so capture efficiency improves markedly. Demulsified droplets are captured and carried to the surface by buoyancy, where they gather as a scum layer.

Step three is automatic slag discharge, which is where many otherwise good designs fail in service. Scum is removed continuously by an automatic slag-discharge system and the effluent stays within specification. The reaction runs fully enclosed and pressurized with a retention time of under 15 minutes, and the unit is equipped with an ozone-generation system, a tail-gas destructor and a clean-water backwash system, with DCS/PLC fully automatic control enabling unattended operation.

The generational gap, line by line

Against Fenton plus flocculation-settling, the contrast is consistent. Oil removal moves from chemical oxidation plus settling to ozone catalytic oxidation demulsification plus cyclonic flotation. Treatment effect moves from unstable and prone to re-colorization to colourless, odourless and stable. Reaction time comes down from 60 min or more to 15 min or less. Sludge drops from 4 kg/t at 55% moisture to 0.1 kg/t, roughly one fortieth. Chemical usage falls from large quantities of Fenton reagent and flocculant to a trace water-quality modifier. Decolorization becomes thorough rather than poor. Safety and environment improve because the process is fully enclosed and pressurized with zero leakage instead of open with gas leakage risk. Footprint shrinks from a field of tanks to a skid.

Seen as a whole, CDOF's advantage is not concentrated in one metric. Demulsification changes from chemical stacking to a physical precision strike, speed improves severalfold, and safety and footprint improve together.

What the operating data shows

In a sodium-sulfate solution oil-removal pilot at a new-energy battery-material manufacturer, influent oil was 32.1 mg/L, COD 1215 mg/L and total phosphorus 11 mg/L. After 200 mg/L ozone dosing, oil fell to 2.3 mg/L, a 92.8% removal, COD fell to 285 mg/L, 76.5% removal, and total phosphorus fell to 1.8 mg/L, 83.6% removal. The notable point is that oil, COD and total phosphorus were reduced in the same pass, which is the practical meaning of one-machine, multi-effect treatment.

A second test on ammonium-sulfide and sodium-sulfate wastewater covered the high-concentration end. Raw water oil at or below 500 mg/L treated with 500 mg/L ozone gave effluent oil at or below 0.4 mg/L, a 99.9% removal; raw water oil at or below 100 mg/L with 100 mg/L ozone gave effluent oil at or below 14.8 mg/L. Between them, the two cases cover medium concentration with multi-indicator synergy and high concentration with ultra-high removal, which is a reasonable demonstration of adaptability across the concentration range this industry produces.

Putting it together

Over 99% oil removal is not the achievement of any single step. It comes from ozone catalytic oxidation demulsification, ultra-fine nanobubble flotation and automatic slag discharge working as a system: demulsification solves the mechanism problem of oil that cannot be broken, flotation solves the separation problem of oil that is not cleaned up, and slag discharge solves the operational problem of scum that is not cleared. Fully enclosed, fully automatic and skid-mounted design is what makes that system deployable. For new-energy enterprises, it is an oil-removal route that holds up from mechanism to data.