A Novel Approach for Advanced Treatment of Oily Acidic Wastewater: Oil-Water Separation via Multi-Stage Coalescence

The treatment of oily acidic wastewater remains a persistent environmental challenge in industries such as chemical processing, metallurgy, and biomass conversion. This wastewater stream is characterized by high corrosivity and a complex oil phase. Acidic media (e.g., sulfuric and hydrochloric acid) destabilize the surface charge of oil droplets, promoting emulsification. The resulting tiny oil droplets (10–30 μm), with their large specific surface area and high stability, resist removal by gravity sedimentation or conventional flotation, resulting in excessive total petroleum content and threatening the ecological safety of aquatic bodies.

Technical Principle: Gradient Coalescing Achieves Micro-Oil Droplet Capture.

The Brator WYS horizontal oil-water separator is built on a "multi-stage coalescence" core, establishing a four-stage oil droplet removal system through the synergy of physical fields and materials science：

• Cyclone Separation Zone: Utilizing the centrifugal force generated by fluid rotation, free oil droplets with large density differences (>50μm) are rapidly lifted to the surface, achieving initial oil-water separation.

• Coarse Coalescing Zone: Packed with oleophilic fibrous media, this zone captures tiny oil droplets via van der Waals forces, promoting their coalescence into larger droplets (>100 μm).

• Polymer Coalescing Zone:This zone utilizes a patented polymer membrane whose microporous surface directionally captures 20–50 μm emulsified oil. The membrane's internal channels prolong the residence time of oil droplets, thereby enhancing coalescence.

• Corrugated Plate Coalescing Zone: The surface of the corrugated plate is treated with superhydrophobic modification to form a uniform liquid film layer, further trapping 10-20μm oil droplets, while simultaneously accelerating oil-water separation using the shallow pool principle.

Corrosion Resistance Breakthrough: A Specialized Coating for Extreme Operating Conditions

To address the corrosion problem caused by acidic wastewater, the inner wall of the equipment employs an epoxy resin + nano-ceramic composite coating. This coating achieves long-term protection through the following mechanisms:

1. Chemical Inertness: Nano-ceramic particles fill the coating pores, blocking H⁺ ion penetration;

2. Physical Barrier: A high-crosslinking density epoxy resin network slows the diffusion of corrosive media;

3. Self-Healing Property: Ceramic particles at micro-cracks oxidize to form a dense oxide layer, autonomously repairing corrosion pathways.Actual testing shows that under conditions of pH=2 and temperature 60℃, the coating's corrosion resistance reaches ISO 9227 standard level 5, extending the equipment maintenance cycle to 18 months.

Engineering Practice: From End-of-pipe Treatment to Resource Recycling

 In a pickling wastewater treatment project at a steel plant, the WYS separator reduced the total oil content from 800 ppm to 60 ppm. It also enabled the recovery of 12 tons of oil per month, which was directly reused as fuel in the plant's heating furnace. The separated iron-containing sludge, after magnetic separation, achieved an 85% iron resource recovery rate. This case validates the dual advantages of this technological approach in resource recovery and waste reduction: by precisely intercepting micro-oil droplets, it avoids the inhibitory effect of oil on microorganisms during subsequent biochemical treatment, and transforms the oil and sludge in the wastewater into usable resources, forming a closed-loop system of "pollution control - resource recovery - recycling".

Conclusion

The Brator WYS horizontal oil-water separator, through its innovative integration of multi-stage coalescence and corrosion-resistant coatings, effectively addresses the two primary challenges of oily acidic wastewater treatment: the removal of micro-oil droplets and the prevention of rapid equipment corrosion. Its three-phase continuous separation design increases the resource utilization rate of oil and sludge to over 90%, and the wastewater reuse rate to 85%, significantly reducing the company's environmental protection costs. This technology not only offers a new paradigm for treating challenging industrial wastewater but also advances the goal of "zero liquid discharge" by valorizing recovered oil and minimizing sludge. This provides critical technical support for the industry's green transformation.