Efficient Treatment of Refinery Desalter Wastewater: A Technological Breakthrough in Pure-Physical Demulsification
In refinery wastewater treatment systems, desalter effluent (desalter draw-off water) has long been a recognized challenge in the pretreatment stage due to its characteristics of high oil content, high emulsification, and drastic water-quality fluctuations. Traditional demulsification and oil-removal processes that rely on chemical agents not only incur high operating costs but also generate secondary pollution problems such as hazardous waste sludge disposal. This article systematically explains how SINOKLE (Shenzhen SINOKLE Technology Co., Ltd.) achieves highly efficient, pure-physical separation without chemical addition through the synergistic process of a “high-efficiency coalescing oil remover + CDFU cyclone dissolved-air flotation,” providing the industry with a green, economical, and reliable solution.
I. Industry Pain Points: The Treatment Dilemma of Highly Emulsified Oily Wastewater
In the electric desalting stage of atmospheric and vacuum distillation units, large amounts of wash water must be injected to remove inorganic salts from crude oil, generating desalter effluent with the following typical characteristics:
High emulsification: Under the action of electric fields and surfactants, oil droplets are highly dispersed, forming a stable “oil-in-water” emulsion with micron-scale particle sizes, which is difficult to treat by conventional gravity settling.
Complex composition: In addition to dispersed oil and emulsified oil, the wastewater often contains colloidal matter, asphaltenes, and suspended solids (SS), further increasing the difficulty of separation.
Severe fluctuation: Changes in crude oil properties and unit operations cause frequent variations in the oil content and emulsification degree of the effluent, imposing extremely high requirements on the impact resistance of the treatment system.
Faced with such wastewater, the limitations of traditional technical paths are obvious: large-tank gravity settling is inefficient and occupies a large area; chemical demulsification continuously generates high reagent costs and hazardous-waste disposal pressure. The industry urgently needs a new, highly efficient, stable, and clean treatment solution.
II. Core Technology: From “Passive Settling” to “Active Coalescence”
The solution proposed by SINOKLE fundamentally changes the physical mechanism of oil-water separation - no longer relying on tiny density differences for natural floating, but instead accelerating oil droplet collision through “forced coalescence,” combined with “cyclone dissolved-air” to achieve highly efficient separation.
Primary enhancement: High-efficiency coalescing oil remover (coalescence / coarsening)
As the core of pretreatment, this equipment contains patented coalescing packing. Its working principle utilizes the super oleophilic and hydrophobic characteristics of specially formulated materials, causing the tiny emulsified oil droplets flowing through it to collide, adsorb, and coalesce, significantly increasing the oil droplet size. According to Stokes' law, the oil droplet floating velocity is proportional to the square of its diameter; the greatly increased size of coalesced oil droplets fundamentally improves separation efficiency, creating favorable conditions for subsequent advanced treatment.
Secondary core: CDFU cyclone dissolved-air flotation unit
This is the key step in achieving highly efficient separation. CDFU innovatively integrates cyclone centrifugal separation with micro-bubble dissolved-air flotation technology.
Micro-bubble generation: The system can generate micro-bubbles with uniform size and a diameter of 5-30 μm, which are smaller and have a larger specific surface area than traditional flotation bubbles, significantly enhancing the capture capability for fine oil droplets.
Cyclone-field enhancement: Wastewater enters the unit tangentially, forming a strong swirling flow; under centrifugal force, heavy particles are pre-separated, while the collision probability between oil droplets and micro-bubbles is greatly increased.
Rapid separation: The bubbles adhere to the coalesced oil droplets, forming an “air-oil” complex that rapidly floats upward under buoyancy, achieving rapid separation of oil, water, and sludge, with a hydraulic retention time reducible to within 5 minutes.
III. Process Advantages: The Unification of Economy, Environmental Protection, and Reliability
Compared with traditional methods, the “high-efficiency coalescing oil remover + CDFU” combined process demonstrates all-round competitive advantages:
| Comparison Dimension | Traditional Chemical Demulsification + Gravity Settling / Flotation | SINOKLE Pure-Physical Synergistic Process |
|---|---|---|
| Separation mechanism | Relies on chemical demulsification, then natural separation by density difference | Physical coalescence enlarges oil droplets; cyclone flotation achieves active, highly efficient separation |
| Effluent stability | Poor resistance to water-quality fluctuation; effluent indicators easily exceed standards | Strong shock-load resistance; effluent oil content and suspended solids stably meet standards |
| Footprint | Settling tanks and large pools occupy vast areas | Skid-mounted, modular design; footprint only 1/3 of traditional methods |
| Secondary pollution | Generates large amounts of oily chemical sludge (hazardous waste); difficult and costly disposal | Zero chemical addition; eliminates hazardous waste sludge at the source |
| Operating cost | Continuous high reagent costs and hazardous-waste disposal expenses | Mainly electricity consumption; operation and maintenance costs greatly reduced |
| Resource recovery | Recovered oil has high water content and poor quality | Recovered waste oil has low water content (0.5%-10%) and high quality; can be directly returned to refining for profit |
IV. Empirical Case: Authoritative Project Validates Outstanding Performance
Taking SINOKLE's actual case at a large petrochemical enterprise as an example:
Influent water quality: oil content as high as 5000-80000 mg/L, and containing a large amount of emulsified crude oil.
Treatment target: meet the influent requirements of subsequent biological treatment (oil content < 200 mg/L).
Operating results: after “coalescence + CDFU” treatment, the effluent oil content is stably reduced to below 50 mg/L, and the separated waste oil has an extremely low water content (< 1%), which can be directly returned to the crude oil system for recovery, truly realizing “turning waste into treasure.”
V. Conclusion
Under the “dual-carbon” background, refining and chemical enterprises' demand for energy conservation, emission reduction, and resource recovery is becoming increasingly urgent. With its “coalescence coarsening + CDFU cyclone dissolved-air flotation” technology, SINOKLE has successfully broken the inherent mindset that desalter effluent must be treated by “adding chemicals,” providing the industry with a new paradigm of highly efficient, compact, and green pure-physical oil removal.
