A New Paradigm for Treating Highly Emulsified Sour Wastewater: Cost Reduction and Efficiency Gains with a Combined Physical Process
In the petrochemical refining field, the treatment of vacuum-top sour wastewater from atmospheric-vacuum distillation units has always been a key environmental challenge. This wastewater is strongly acidic, high in oil (especially emulsified and dissolved oil), high in COD and complex in pollutants; conventional processes (simple oil separation, chemical demulsification or ordinary flotation) often fall short because of low efficiency, high operating cost and poor stability. Finding an efficient, economical and reliable treatment scheme is urgent.
The innovative process proposed by SINOKLE Technology — the CDFU (cyclonic dissolved air flotation) working synergistically with the KHC coalescing oil remover provides a completely new approach to the vacuum-top sour water problem. The core of the process lies in deep optimisation of its physical separation mechanisms and their synergistic enhancement.
Sour wastewater treatment process flow diagram
CDFU Cyclonic dissolved air flotation: microbubbles driving efficient separation
CDFU technology abandons the traditional dissolved-air approach and innovatively adopts a high-efficiency cyclonic dissolved air system. Its unique structural design generates intense cyclonic shear, cutting and dissolving gas at high speed under pressure to produce a large population of micro-nano bubbles (5-30 microns) that are finely sized, evenly distributed and highly stable. Like efficient porters, these microbubbles, with their huge specific surface area and surface energy, rapidly attach to the oil droplets and suspended solids in the vacuum-top wastewater, forming stable gas-particle complexes. With the optimised flow field, the bubble swarm carries the pollutants quickly up to the water surface, where they are efficiently removed by the precision skimming mechanism. Its removal efficiency for emulsified oil and fine suspended solids far exceeds conventional flotation, laying a solid foundation for subsequent deep oil removal.
KHC coalescing oil remover: gradient coalescence for deep purification
After CDFU pretreatment, the oil forms in the wastewater have changed markedly, but residual finely dispersed oil — especially the hard-to-treat dissolved and emulsified oil — still requires deep removal. The KHC coalescing oil remover is designed exactly for this. Its core is the special gradient-density coalescing media packed inside. The media is modified to be oleophilic and hydrophobic, with excellent surface properties. As the wastewater passes through the precision filter cartridges, the media's huge specific surface area and tortuous channels provide ample collision and coalescence opportunities for the oil droplets. Driven by van der Waals forces and surface tension, the fine droplets keep colliding, merging and growing (the coalescence effect) until they are large enough to float to the oil collection zone at the top of the unit for automatic collection and discharge. The KHC achieves deep, efficient and stable removal of residual oil, especially the stubborn emulsified oil.
On-site treatment of highly emulsified wastewater at a petrochemical enterprise
CDFU + KHC combined process shows significant advantages in vacuum-top sour water treatment:
1. Efficient and stable: CDFU the CDFU efficiently removes most free oil and suspended solids while the KHC performs deep demulsification and oil removal; the effluent oil content and COD stably meet national environmental standards (e.g. oil content <5 mg/L).
2. Strong shock resistance: highly adaptable to influent fluctuations (oil content, acidity), stable and reliable operation.
3. Economical and energy-saving: compared with conventional processes, chemical consumption (especially the expensive demulsifier) drops markedly; the CDFU offers high dissolved-air efficiency and low energy consumption, cutting overall operating cost substantially.
4. Compact footprint: modular design, simple flow, small floor area, especially suitable for revamps of existing units or space-constrained sites.
Application example: after a large domestic petrochemical enterprise adopted this process for its atmospheric-vacuum distillation unit, its vacuum-top sour water treatment improved markedly: the influent oil averaged 800 mg/L and COD exceeded 5000 mg/L; after treatment the effluent oil is stably below 3 mg/L and the COD below 100 mg/L, far better than the discharge standards, with operating cost about 40% lower than the original chemical method.
Against the backdrop of ever-stricter environmental requirements, SINOKLE Technology's CDFU cyclonic dissolved air flotation + KHC coalescing oil remover process, with its outstanding physical separation performance and significant economic and environmental benefits, provides an efficient, economical and green innovative solution to the long-standing "tough old problem" of vacuum-top sour water in the refining and chemical industry.
