Case Review: How SINOKLE CDFU Cracked the "Hard Nut" of High-Oil Wastewater at Dushanzi Petrochemical

In refinery production, electric desalting cut water has long been a difficulty in wastewater treatment due to its complex composition and high degree of emulsification. The oil droplets in this kind of wastewater are fine, and conventional processes struggle to achieve efficient and stable oil-water separation. In 2019, PetroChina Dushanzi Petrochemical Company joined hands with Shenzhen SINOKLE Technology Co., Ltd. to introduce two-stage CDFU (cyclonic dissolved gas flotation) technology, successfully overcoming this technical bottleneck. This article reviews this benchmark case in depth from four dimensions: project background, technical route, implementation process, and operating results.

I. Project Background: Facing the Challenge of Difficult Emulsified Wastewater

Dushanzi Petrochemical's electric desalting wastewater has the typical characteristics of "high oil content, high emulsification." The wastewater contains not only free oil but also a large amount of emulsified oil formed by vigorous mixing. The oil droplet size is mostly concentrated in the 10-20 μm range, and its density is extremely close to that of water.

In traditional processes, relying solely on gravity settling for separation not only requires an extremely long retention time of 50-70 hours, but also produces large fluctuations in effluent quality, making it difficult to meet the strict requirements of subsequent biological treatment units. At the same time, the traditional large-tank settling process has disadvantages such as a wide footprint, high risk of volatile organic compound (VOCs) escape, and high operation and maintenance intensity. Therefore, finding an efficient, intensive pretreatment technology with no chemical addition became the key demand of this project.

II. Technical Breakthrough: Why Choose the CDFU Pure-Physical Process?

In response to the water quality characteristics of Dushanzi Petrochemical, SINOKLE abandoned the traditional "chemical demulsification + settling" route and instead adopted two-stage CDFU cyclonic dissolved gas flotation as the core solution.

Its technical advancement is mainly reflected in the following three dimensions:

1. Micro-Nano Bubble Demulsification Technology

CDFU generates a large number of micro-nano bubbles with a diameter of only 5-30 μm through an efficient dissolved gas system. With extremely high specific surface area and surface energy, these bubbles can actively capture and wrap small oil droplets and suspended solids in water, forming "bubble-oil droplet" aggregates, significantly reducing their overall density and thus achieving rapid float-up separation at the millisecond level.

2. Cyclonic Centrifugal Strengthening Mechanism

The unique cyclone field design inside the equipment gives the fluid a powerful centrifugal force. Under the action of the centrifugal force field, the density differences among the three phases of oil, water, and solids are sharply amplified, greatly improving separation efficiency, and it is particularly suitable for treating highly stable emulsions.

3. Full-Process Pure Physical Treatment

The entire treatment process requires no addition of demulsifiers or flocculants, eliminating secondary pollution from chemical agents at the source, and also avoiding the high agent costs and hazardous waste sludge disposal problems they generate.

Based on the above technical principles, SINOKLE tailored a two-stage series process for the project: the first-stage CDFU is responsible for removing most of the oil, and the second-stage CDFU performs deep fine filtration. The entire system adopts a modular skid-mounted design with a footprint of only 11 m × 3 m × 5.2 m, greatly saving land resources and enabling rapid installation and commissioning.

III. Implementation Results: Data Witnesses Hard-Core Strength

The project was officially put into operation in 2019, with a designed treatment capacity of 100 m³/h. After long-term stable operation, all system indicators have performed excellently. The core monitoring data are as follows:

The data show that after two-stage CDFU treatment, the effluent is clear and transparent, and the oil content and suspended solids indicators are far below the design standards, fully meeting the inlet requirements of subsequent treatment units and completely solving the long-standing problem of cut water exceeding standards.

IV. Conclusion

The success of the Dushanzi Petrochemical electric desalting wastewater treatment project is a powerful verification of SINOKLE CDFU technology under extreme operating conditions. It not only proves the unique advantages of pure physical separation technology in dealing with highly emulsified oily wastewater, but also provides an efficient, green, and replicable pretreatment model for the refining industry.

In the future, SINOKLE will continue to deepen its work in the field of industrial wastewater treatment, using continuous technological innovation to help enterprises achieve the dual goals of cost reduction, efficiency improvement, and green transformation.