Physical Oil Removal vs Chemical Demulsification: Oilfield Produced Water Treatment Welcomes the 'Zero-Chemical' Transformation
In the daily operations of oilfields and refining enterprises, the treatment of tank-farm draw-off water (also known as "tank-bottom water") is an unavoidable environmental challenge. This intermittently discharged wastewater is characterized by high oil content, severe fluctuation and complex composition. Traditionally relying on the "chemical demulsification + settling" process route, it is now showing fatigue under the dual pressures of increasingly strict environmental supervision and cost reduction. Today, the pure-physical treatment process centered on SINOKLE's CDFU cyclonic dissolved air flotation is bringing an efficient, green and economical transformation to the industry.
The pains of the traditional chemical method: cost, hazardous waste and instability
For a long time, the mainstream method for tank-farm draw-off water has been to dose demulsifiers and flocculants, then separate through separator tanks, flotation tanks or settling tanks. This route exposes many pain points in practice:
Secondary pollution and hazardous-waste problems: chemical dosing produces large amounts of oily chemical scum or sludge, which belong to hazardous waste with high disposal costs and environmental risks.
Weak shock resistance: the quality and quantity of tank-farm draw-off water fluctuate drastically. Traditional processes lag in adjustment; once the incoming oil content spikes, effluent exceedance easily occurs, impacting the downstream wastewater treatment system.
High operating cost: continuous chemical expenses, hazardous-waste disposal fees, and high maintenance costs from equipment corrosion and scaling constitute a heavy operational burden.
Poor recovered-oil quality: chemicals contaminate the recovered foul oil, forming "aged oil" with degraded quality and low re-refining value, which may even affect the main process.
SINOKLE's solution: the pure-physical breakthrough of coalescence + cyclonic flotation
Facing the dilemma of the traditional chemical method, SINOKLE proposes a completely different approach: abandon chemical dependence and achieve efficient oil-water separation through multi-stage strengthened pure-physical mechanisms. Its core process route is "high-efficiency coalescing oil remover + CDFU cyclonic dissolved air flotation".
Stage-1 strengthening: high-efficiency coalescing oil removal. The wastewater first enters the high-efficiency coalescing oil remover. Its specially formulated coalescing material prompts the tiny oil droplets in the water to rapidly collide and coalesce into large oil beads, laying the foundation for subsequent rapid separation.
Core separation: CDFU cyclonic dissolved air flotation. This is the key to efficient and stable separation. The CDFU unit innovatively fuses cyclonic centrifugal separation and micro-fine bubble flotation.
Micro-fine bubbles: the patented dissolved-air release system produces microbubbles of only 5–30 μm in diameter, with huge specific surface area, far surpassing traditional large bubbles in capture ability and adsorption efficiency for oil droplets.
Cyclonic strengthening: the water forms a strong swirl inside the tank; under centrifugal force it not only strengthens oil-water separation but also greatly increases the collision probability between oil droplets and microbubbles.
Under this synergy, oil droplets are rapidly removed and the effluent becomes clear. The whole process is pure physical separation requiring no chemical dosing whatsoever.
Three overwhelming advantages of the pure-physical process
| Comparison dimension | Traditional chemical demulsification + settling/DAF | SINOKLE pure physical (coalescence + CDFU) |
|---|---|---|
| Core mechanism | Relies on chemicals to change interfacial properties, pollutant transfer | Pure physical coalescence & separation, pollutant directly removed |
| Secondary pollution | Large oily chemical sludge (hazardous waste), hard to dispose | Zero chemical addition, no chemical sludge, thoroughly eliminates hazardous waste |
| Recovered-oil quality | "Aged oil", poor quality, hard to re-refine | Pure recovered oil, low water content, directly reusable in crude tank, economic value |
| Shock resistance | Sensitive to quality/quantity fluctuation, unstable effluent | Strong shock resistance, adapts to severe oil fluctuation, stable |
| Operating cost | High continuous chemical + hazardous-waste disposal fees | Only consumes a little electricity, O&M cost greatly reduced |
| Footprint | Settling tanks, DAF tanks, huge | Skid-mounted, compact, a fraction of traditional |
Evidence case: from theoretical advantage to stable compliance in practice
This process has been successfully applied in multiple large petrochemical enterprises and has achieved operation results certified by authoritative bodies. For example, in the electric-desalting wastewater treatment project of Sinopec Cangzhou Refining, the core process uses a coalescing pressure oil remover + CDFU cyclonic dissolved air flotation. After pure-physical treatment, the effluent oil content is stably at 35 mg/L, far better than the design standard, and the whole process adds no chemicals, achieving the dual goals of efficient oil removal and sludge reduction.
Conclusion
The treatment of tank-farm draw-off water is no longer a helpless choice of "treating pollution with pollution". With CDFU cyclonic dissolved air flotation as its core patented technology, SINOKLE is leading the industry into a new pure-physical era of "zero chemicals, zero hazardous waste, high recovery". This is not only a positive response to environmental regulations, but also a wise choice for cost reduction and green sustainable development.
