One Skid Instead of Three: Putting Ozone Oxidation and Flotation in the Same Shell

Anyone in the industrial wastewater treatment circle knows the common truth: oxidation and separation are two different things, usually done in two steps. First build an oxidation reactor to bring down COD, then build a settling tank or flotation tank to separate sludge from water. The SINOKLE CDOF simply does not play it that way. One skid-mounted unit handles both oxidation and flotation. Here is the technical chassis, taken apart.

A breakdown of the five major systems

System 1: oxygen generation

CDOF comes with its own VPSA or PSA oxygen-generation module that directly purifies oxygen from air for the ozone generator. No externally purchased liquid oxygen tanks are needed, nor the safety approval process for liquid oxygen storage and transport. This is especially critical for overseas projects, where many oilfields sit in places with weak infrastructure and the liquid oxygen supply chain simply cannot keep up.

System 2: ozone generation

It adopts dielectric barrier discharge ozone generation tubes, using the high-purity oxygen produced by the oxygen generation system as the gas source, with adjustable ozone concentration and output. The key parameter: ozone concentration is typically 80-150mg/L with an oxygen source, far higher than the air-source solution.

System 3: high-efficiency ozone dosing

This is one of the core links that distinguishes CDOF from the traditional bubbling method. Rather than simply using a titanium diffuser to pump gas into the water, it achieves efficient gas-liquid contact through a Venturi injector or static mixer, greatly improving ozone mass-transfer efficiency. Under fully enclosed, pressurized conditions, Henry's law dictates that the saturated solubility of ozone in water increases severalfold.

System 4: multi-catalytic reaction

The most technically sophisticated part. Homogeneous catalysis uses transition metal ions such as Fe2+ and Mn2+ to catalyze O3 directly in solution, decomposing it into ·OH. Heterogeneous catalysis uses supported metal oxide catalysts, MnOx/Al2O3, TiO2-based catalysts and similar, to provide a solid-phase reaction interface. The two catalytic pathways run in parallel, reducing the risk of system performance fluctuation caused by deactivation of a single catalyst.

System 5: cyclonic dissolved-air flotation

It adopts the cyclonic dissolved-air flotation technology independently developed by SINOKLE, using microbubbles released from dissolved air water, typically 30-50μm in diameter, to efficiently capture oil droplets and suspended solids in the cyclonic field. The centrifugal field generated by the cyclone accelerates the collision probability between bubbles and pollutants, and separation efficiency is superior to that of traditional horizontal-flow flotation.

In-depth analysis of seven synergistic mechanisms

Once the hardware is understood, seven mechanisms turn out to be working simultaneously inside the unit.

• Homogeneous catalysis: dissolved metal ions catalyze O3 to ·OH, with a fast reaction rate and no need for solid-liquid separation.
• Heterogeneous catalysis: the solid-phase catalyst provides the reaction interface, and the catalyst can be recovered and regenerated.
• Cyclone technology: the cyclonic field increases gas-liquid-solid three-phase contact area, intensifying mass transfer.
• Dissolved-air flotation: microbubbles efficiently separate oils and suspended solids.
• Cavitation effect: the local high temperature and high pressure produced by hydraulic cavitation, instantaneously about 5000K, breaks H2O down into ·OH and ·H, replenishing the free-radical supply.
• Supercritical catalytic oxidation: the cavitation micro-zone approaches supercritical water conditions, T>374°C and P>22.1MPa, and the organic oxidation rate increases by orders of magnitude.
• Fully enclosed pressurized oxidation: improves ozone solubility and eliminates VOC escape, avoiding secondary pollution.

These seven mechanisms do not act independently, they stack positively. Cavitation both generates free radicals and intensifies gas-liquid mixing; the cyclone both serves flotation separation and promotes the three-phase mass transfer of the catalytic reaction. That is the synergistic enhancement design logic, and it is why the unit is smaller than the sum of its parts would suggest.

Multi-dimensional comparison with traditional processes

• Number of process units: CDOF needs 1 integrated skid-mounted unit; traditional ozone oxidation plus flotation needs 2-3, oxidation plus flotation plus filtration; Fenton plus coagulation-sedimentation needs 3-4, acid adjustment plus oxidation plus alkali adjustment plus sedimentation.
• Chemicals: CDOF needs only a small amount of catalyst replenishment; the ozone route needs ozone; Fenton needs FeSO4 plus H2O2 plus acid plus alkali plus PAM.
• Chemical sludge: very little for CDOF, little for ozone, and a large amount of iron-containing sludge for Fenton.
• Ozone utilization rate: high for CDOF thanks to pressurized plus catalytic operation, low to medium for atmospheric bubbling.
• VOC escape: none from the fully enclosed CDOF; yes for both alternatives.
• Footprint: small for skid-mounted integration, medium for ozone plus flotation, large for Fenton.
• Applicable scenarios: CDOF targets oilfield, petrochemical and coking advanced treatment; ozone plus flotation is general industrial wastewater; Fenton spans various industrial wastewaters.

As that comparison shows, CDOF's dimensionality-reduction strike lies not in any single outstanding indicator, but in using one compact unit to cover tasks that traditionally require two or even three process stages. For overseas projects, skid-mounting to site, small footprint, no need to build a liquid-oxygen station, and no chemical sludge generation: each is a real, tangible cost advantage.

Three delivery cases

An African oilfield at 250m³/h, a Guinea iron ore project at 10m³/h, and a Congo oilfield at 400m³/h. Together they cover full-scale validation from pilot level to large industrial level. At 400m³/h, the scale argument in the field of oilfield produced-water advanced treatment is already convincing enough.