Oily Wastewater Treatment for Dispersed & Emulsified Oil
VSEP membrane systems remove free oil, dispersed oil, and stable oil emulsions without chemical demulsifiers or thermal breaking—delivering high recovery and polished permeate that meets discharge or reuse targets. This makes VSEP an ideal technology for Oily Wastewater Treatment.
Highlights for engineers
- Breaks stable oil emulsions physically (no demulsifiers/heat)
- High-shear, wide-channel design resists oil fouling and concentration polarization
- UF/NF/RO options to target dispersed, emulsified, and dissolved oil
- Proven on bilge water, produced water, refinery effluent, and machining coolant
- Integrates easily after skimmers/DAF/clarifiers; pairs with RO polishing for reuse
Why Oily Wastewater Is Hard to Treat
Oil in water occurs in four distinct forms—each demanding different separations. Regulators classify and limit these discharges under industrial wastewater rules such as the U.S. EPA’s Centralized Waste Treatment Effluent Guidelines.
Free Oil
- Description: Large droplets that rapidly float and form a sheen.
- Typical Treatment: API separators, skimmers, cyclones.
Dispersed Oil
- Description: Small oil droplets stabilized by interfacial charge (sensitive to conductivity).
- Implication: Coagulants/flocculants can coalesce droplets; in high-conductivity waters, double-layer compression enables droplet contact and coalescence.
Dissolved Oil
- Description: Limited molecular solubility; pH-driven partitioning can elevate solubility at high pH.
- Implication: RO-level membranes are required to reject dissolved hydrocarbons.
Emulsified Oil (Most Challenging)
- Description: Oil stabilized by surfactants into micelles; often thermodynamically stable.
- Problem: Chemical or thermal breaking can be incomplete, costly, or inconsistent—especially across variable feeds.
Why Conventional Spiral RO Struggles with Oil
- Spacer fouling: Hydrophobic polypropylene feed spacers with similar chemistry to hydrocarbons “wet out,” trapping oil, shrinking channels, and causing ΔP spikes. Acts like an oil sponge
- Surface adhesion: Because of concentration polarization, oil film growth, surface wetting, and pore blocking are accelerated.
- Zero tolerance: Many spiral elements cannot tolerate any oil—dramatically raising pretreatment burden.
How VSEP Overcomes Fouling & Breaks Emulsions
VSEP (Vibratory Shear Enhanced Processing) uses a wide-channel, no-spacer configuration combined with torsional oscillation to maintain free flow and no concentration polarization:
- Extreme surface shear: Membrane oscillates ~50 times per second, imposing up to ~100 Gs force at reversal—disrupting concentration polarization and preventing oil film formation.
- Physical separation: Pressure-driven PV work moves water through the membrane while rejecting oil droplets and micelles—even when emulsions are thermodynamically stable.
- Membrane options:
- UF/NF for dispersed/emulsified oil; permeate oil approaches solubility limits
- RO when dissolved hydrocarbons must be removed
Result: Stable flux, high recovery, and consistent permeate quality with no chemical dependence.
Applications Where VSEP Excels
- Bilge water / shipboard oily wastewater – compact system footprint, variable feed tolerance
- Oilfield produced water – remove residual oil/organics ahead of reuse, boilers, or dicharge
- Refinery desalter effluent – robust separation where surfactants defeat coalescers
- Machining coolant & metalworking wastewater – volume reduce to reduce haul-off
- Refinery end-of-pipe effluent – tighten to discharge limits, relieve existing WWTP
- Sour water & tank bottoms – handles challenging organics and variability
Pair VSEP NF with spiral RO polishing to achieve low-TDS, reuse-grade permeate.
Typical Process Flow
- Primary oil removal: API separator / skimmer / DAF or clarifier
- VSEP UF/NF: High-shear oil rejection; high recovery operation
- VSEP RO: Remove dissolved organics/TDS as needed
- Permeate discharge or reuse; concentrate to waste or oil recovery
Case Studies: Proven Results
Puerto Rico – Bilge & mixed oily wastewater.
System: Existing oil skimmer & clarifier → VSEP NF → RO polishing\ VSEP operates at ~90% recovery.
| Parameter | Unit | Raw Feed | VSEP NF Permeate | Stage 2 RO Permeate | % Reduction |
| Total Solids | mg/L | 8,400 | 3,000 | 150 | 98.2% |
| Dissolved Solids | mg/L | 3,000 | 1,500 | 150 | 95.0% |
| COD (DQO) | mg/L | 11,750 | 1,170 | 580 | 95.0% |
| Oil & Grease | mg/L | 2,000 | 20 | <5 | 99.8% |
California – Produced water for steam generation
System: API + walnut shell filters → VSEP NF → RO polishing
| Parameter | Unit | Raw Feed | VSEP NF Permeate | Stage 2 RO Permeate | % Reduction |
| Hardness | mg/L | 870 | 44 | 0 | 100.0% |
| Dissolved Solids | mg/L | 25,900 | 15,800 | 900 | 96.5% |
| Oil & Grease | mg/L | 220 | 20 | 0.4 | 99.8% |
Engineering & Operations Advantages
- Fouling resistance: High shear suppresses gel layers and oil films
- Stable flux & recovery: Tolerates variable feeds common in oily wastewater
- Simplified chemistry: Oil separation without chemicals or heat
- Modular scale-up: Skid-based systems sized for pilot through full plant
- Integration-ready: Works with existing oil removal equipment to improve outcome
Specifications & Selection Guidance (At a Glance)
- Membrane type: UF/NF for dispersed/emulsified oil; RO for dissolved oil
- Targets: Oil & Grease, COD/TOC reduction, hardness with NF, TDS with RO
- Recovery: Application-dependent; up to ~90% demonstrated in case work
- Feed variability: Handles swings in oil loading and conductivity that frustrate coalescers
(Request a no-cost performance evaluation to receive a data-backed sizing and membrane selection report for your wastewater.)
Oily Wastewater Treatment FAQs
Can membranes treat stable emulsions?\ Yes. VSEP’s high-shear boundary layer control enables physical separation of oil from water—even for thermodynamically stable emulsions where chemicals or heat underperform.
Do VSEP systems require chemical demulsifiers?\ No. VSEP relies on mechanical shear and pressure-driven separation. Some applications may still use light conditioning for optimum performance, but demulsifiers are not required.
Can VSEP treat bilge water, produced water, and refinery effluent?\ Yes. VSEP is proven across bilge water, produced water, refinery desalter effluent, sour water, machining coolant, and end‑of‑pipe refinery streams.
When is RO needed?\ Use RO when you must remove dissolved hydrocarbons or drive TDS and TOC to reuse/discharge specifications.
What about maintenance and cleaning?\ VSEP’s high shear minimizes foulant deposition. Clean-in-place (CIP) are provided with each system.
VSEP, the Only Membrane Option for:
- Oily water treatment systems
- Emulsion wastewater treatment
- Oil water separation membrane
- Produced water oil removal
- Bilge water treatment system
- Refinery wastewater oil removal
- No chemicals and no heat required
Get a No‑Cost Performance Evaluation
Get a data-driven assessment, projected recovery, and membrane selection for your specific oily wastewater.
Contact a VSEP specialist: info@vsep.com\ Learn more:
- VSEP Technology Overview: VSEP technology
- Pilot Testing Services: Pilot Testing Services