SINOKLE CDFU Compact Flotation Unit: The Key to Improving Oily Wastewater Treatment Efficiency
CFU compact flotation technology is an efficient water treatment process: microbubbles efficiently attach to suspended solids and oils, rapidly carrying pollutants to the water surface to form scum for quick separation and removal. It is widely applicable to industrial wastewater treatment, oily water purification, and seawater desalination pretreatment, and features easy operation and stable treatment performance.
Figure 1. Schematic of the internal structure of a conventional CFU
Its workflow mainly includes the following steps:
Gas injection system: a dedicated gas injection device releases a uniform swarm of microbubbles into the water, forming a gas-water mixture and creating ideal conditions for pollutant capture.
Bubble-pollutant attachment: relying on surface tension, microbubbles actively adsorb suspended particles and grease in the water, forming bubble-pollutant aggregates less dense than water.
Rise and enrichment separation: driven by buoyancy, the aggregates rise rapidly and gather at the water surface into a skimmable scum layer, effectively separating pollutants from clean water.
Scum discharge and oil collection: inside the unit, a pressurized closed structure, liquid-level monitoring, and flow-state control enable precise collection and automatic discharge of scum and waste oil, improving treatment continuity.
Improved effluent quality:
After CFU flotation treatment, the suspended solids and oil content of the water are significantly reduced and clarity is improved, laying the foundation for subsequent treatment or compliant discharge.
However, CFU technology also has some limitations:
Its bubbles are relatively large (typically 100-1000 μm), giving poor — often nearly zero — removal of emulsified oil droplets smaller than 20 μm.
The technology usually requires dedicated chemical dosing to assist separation, which not only raises operating costs and makes performance unstable, but also produces a large volume of high-water-content waste oil (classified as hazardous waste), causing secondary pollution.
In addition, the CFU gas injection point is prone to scaling and blockage in high-salinity environments, making maintenance difficult.
Its automatic control precision is relatively poor; when facing flow fluctuations, level and pressure control become unstable, affecting effluent quality.
CDFU® Technology Upgrade Highlights
Building on conventional CFU flotation technology and integrating multiple innovations — ultrafine bubble generation, dissolved-air flotation, coalescing separation, and integrated flotation-cyclone — SINOKLE has developed a new generation of high-efficiency compact flotation unit: CDFU® (Cyclonic Dissolved Gas Flotation Unit). Through the synergy of multiple technologies, the unit significantly improves oil removal efficiency and overall pollutant removal capability, making it the preferred solution for today's high-difficulty industrial wastewater treatment.
Figure 2. Schematic of the new CDFU cyclonic dissolved-air flotation working principle
Compared with conventional CFU technology, SINOKLE CDFU cyclonic dissolved-air flotation technology has the following six core features:
1. Smaller, more uniformly distributed bubbles: CDFU generates microbubbles only 5-30 μm in diameter (D50 ≈ 25 μm) with uniform distribution, whereas conventional CFU bubbles are mostly 100-1000 μm in diameter. The smaller bubbles greatly increase the specific surface area and the collision-adhesion efficiency with oil droplets.
2. Markedly improved emulsified oil removal: thanks to ultrafine bubble technology, CDFU achieves 80%-90% removal of emulsified oil droplets of 0.1-20 μm, where conventional CFU is essentially ineffective.
3. Pure physical demulsification without chemicals: CDFU uses a purely physical demulsification process throughout, with no chemical addition, fundamentally avoiding the generation of oily sludge (hazardous waste) and secondary pollution; the separated oil can be recovered for re-refining.
4. High treatment efficiency and compact structure: CDFU has a hydraulic retention time of only 1-5 minutes and a single-stage oil removal efficiency above 90%. Its swirl design and compact structure give it a footprint only about one-third of conventional equipment.
5. High automation and stable operation: CDFU operates fully automatically in a closed pressurized mode with high level-control precision (e.g., ±5 mm). The system has strong shock resistance, adapts to large fluctuations in water quality and quantity, and delivers stable effluent.
6. Easier operation and maintenance, lower cost: CDFU has a simple internal structure that resists scaling and blockage. Its energy consumption is low and there are no chemical costs, significantly reducing operating and maintenance expenses.
Figure 3. CDFU cyclonic dissolved-air flotation application example
