The main pollutants in oily wastewater include floating oil, emulsified oil, dissolved oil, and suspended particles. Direct discharge can easily lead to water eutrophication, ecological chain disruption, and pipeline blockages. Traditional treatment technologies (such as gravity separation, single flotation, biochemical treatment, etc.) have limitations such as low oil removal efficiency (especially for emulsified and dissolved oils), weak resistance to shock loads, and long treatment cycles.

As a type of dissolved gas flotation technology based on cyclonic enhancement, the CDFU process achieves efficient oil separation through the synergistic effect of cyclonic shearing and microbubble adsorption, providing an efficient solution for treating oily wastewater.

1. Introduction to the Cyclonic Dissolved Gas Flotation Unit

After pretreatment, the wastewater enters the cyclonic dissolved gas flotation tank where pressurized dissolution generates tiny bubbles with diameters of 5-30um. Meanwhile, the centrifugal force produced by the cyclonic device enhances the collision and adsorption between oil droplets and bubbles, forming a gas-solid-liquid complex lighter than water. Under the dual effects of cyclonic shearing and buoyancy, this complex rapidly floats to the surface and is removed, achieving efficient oil-water separation.

2. Analysis of Treatment Effects of the CDFU Process

(1) Oil Removal: The total oil removal rate of the CDFU process can reach 90%-95%.

(2) COD Removal: The total COD removal rate of the CDFU process can achieve 30-50%, which can be further improved by optimizing cyclonic intensity and dissolved gas parameters.

(3) Co-removal of Suspended Solids and Other Pollutants: The SS removal rate exceeds 90%; simultaneously, the CDFU process also shows good removal effects on characteristic pollutants such as petroleum substances and volatile phenols, demonstrating its broad-spectrum purification capability for complex oily wastewater.

3. Optimization of Key Influencing Factors

(1) Conditions for Cyclonic Dissolved Gas Flotation:

By adjusting the pressure and time of dissolved gas, the bubble diameter distribution can be changed; meanwhile, optimizing the rotational speed of the cyclone can enhance the coalescence of oil droplets and improve the adsorption efficiency with bubbles.

Through the addition of agents (e.g., flocculants like PAC), the binding efficiency between flocs and bubbles can be enhanced, further improving the cyclonic flotation separation effect.

Integration of intelligent control systems, combined with online monitoring (such as oil content, COD sensors), enables real-time adjustment of process parameters.

4. Advantages Over Traditional Processes

Compared to traditional flotation methods (oil removal rate 70%-85%) and biochemical methods (treatment cycle >24 hours), the CDFU process has the following advantages:

(1) High oil removal efficiency: Synergistic action of cyclonic shearing and bubble adsorption enables efficient separation of emulsified and floating oils, with oil removal rates reaching 90%-95%;

(2) Strong resistance to shock loads: Capable of withstanding fluctuations in influent oil content (±30%), ensuring stable effluent water quality;

(3) Short treatment cycle: Only 1/5-1/10 of that required by traditional biochemical methods;

5. Conclusion

In summary, the CDFU cyclonic dissolved gas flotation process possesses application advantages of high efficiency, stability, and low cost in the field of oily wastewater treatment, providing technical support for industrial wastewater compliance discharge.