Analysis of Vacuum Evaporation Technology for Treating Oil-Containing Wastewater: Applicable Scenarios, Process Design, and Economic Advantages.

1. Types of Oil-Containing Wastewater and Applicable Industries for Vacuum Evaporation Technology

Low-temperature vacuum evaporation technology has become the mainstream choice for treating oil-containing wastewater due to its efficient oil-water separation and low energy consumption. Below are typical applicable scenarios and industry cases:Cutting Fluid Wastewater、Emulsion Wastewater、Machinery Cleaning Wastewater、Ink Cleaning Wastewater、Rust Prevention Oil Wastewater，etc.

Note: Low-temperature vacuum evaporation technology is particularly suitable for projects with a daily treatment capacity of ≤30 tons and oil concentrations ≤30%. For wastewater with high suspended solids (>5%), additional pretreatment (e.g., centrifugal separation, ceramic membrane filtration) is required.

2、Vacuum Evaporation Process Selection and Flow Design

2.1、Vacuum Evaporator or Vacuum Crystallizer Selection Strategy

2.2、Vacuum Evaporator and Vacuum Crystallizer Combined Process Flow

Process Option 1: Low-Temperature Vacuum Evaporator Dominant Process (Suitable for Emulsion Wastewater and Cleaning Wastewater)

Coalescing Tank → Demulsification Reaction Tank (pH adjustment + coagulation) → Vacuum Evaporator (35-45°C) → Oil-Water Separation Tank
↘ Distilled water (COD <100 mg/L, can be reused or discharged)
↘ Concentrated oil phase (purity ≥85%, can be resourceized)

Process Option 2: Vacuum Crystallizer Enhanced Process (Suitable for High-Concentration Cutting Fluid and Rust Prevention Oil Wastewater)

Centrifugal Separation → Scraper Vacuum Crystallizer (50-60°C) → Spiral Press Filter → Waste Oil Residue (Calorific value >4,000 kcal/kg)
↘ Condensed water (oil content ≤80 mg/L, sent to biological system)

3. Economic Comparison of Vacuum Evaporation Technology

1. Cost Comparison (Example: 10 tons/day Cutting Fluid Wastewater Treatment)

2. Advantages Summary (Compared to Traditional Chemical Demulsification, Centrifugal Separation, etc.)

4. Vacuum Evaporation Technology Application Cases

Case 1: Automotive Parts Factory Emulsion Wastewater Treatment

  • Scale: 15 tons/day, oil content 12%, COD 28,000 mg/L
  • Process: Low-temperature evaporation + activated carbon adsorption
  • Results:
    • Effluent water oil content <10 mg/L, reused in production line
    • Annual lubricating oil recovery of 135 tons, generating 540,000 RMB revenue
    • Hazardous waste disposal costs reduced from 720,000 RMB/year to 60,000 RMB/year

Case 2: Precision Mechanical Processing Cutting Fluid Wastewater Treatment

  • Scale: 8 tons/day, oil content 18%, contains copper shavings
  • Process: Scraper evaporation + metal recovery system
  • Results:
    • Waste oil residue calorific value reached 4,500 kcal/kg, sold as fuel
    • Copper shaving recovery rate of 95%, generating 220,000 RMB annual revenue
    • Overall treatment cost reduced by 68%

5. Implementation Recommendations

  • Pretreatment Optimization: For wastewater with suspended solids >3%, ceramic membranes or centrifugal separation should be prioritized for solid-liquid separation.
  • Energy Recovery Design: Utilize the evaporated condensation water’s residual heat for preheating influent, reducing energy consumption by 15-20%.
  • Compliance Assurance: Effluent must be tested for petroleum content, COD, heavy metals, etc., to ensure compliance with the “Comprehensive Wastewater Discharge Standards” (GB8978-1996).

Conclusion

Low-temperature vacuum evaporation technology provides an effective solution for oil-water separation and resource recovery, delivering both cost reduction and efficiency gains for oil-containing wastewater treatment. For projects with a daily treatment capacity ≤30 tons, the investment payback period is typically 2-3 years, with long-term operational economics significantly superior to outsourced treatment. It is recommended for owners to prioritize pilot tests, select evaporators based on oil content characteristics, and integrate automation systems to reduce operational complexity.

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