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DAF Systems for Oil & Gas

High-efficiency dissolved air flotation systems engineered for produced water and refinery wastewater, delivering reliable oil and solids removal in the most demanding upstream and downstream environments.

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Free interactive DAF sizing calculator. Calculate dissolved air flotation surface area, recycle flow, saturator volume, and power.

FOG Recovery & DAF Systems

FOG removal food industry DAF systems for fat oil grease recovery food processing.

DAF Hydraulic Loading

Design DAF systems for correct hydraulic loading. Surface area, rise rate and detention time calculations for your flow.

DAF Systems for Food Processing

DAF systems for food processing wastewater treatment. Efficient FOG removal, suspended solids separation and reliable discharge compliance.

Industry Overview

Oil & Gas Wastewater Challenges

Understanding the diverse wastewater streams and treatment requirements across upstream, midstream, and downstream oil and gas operations.

The oil and gas industry generates a wide spectrum of wastewater streams that demand robust, reliable treatment solutions. In upstream operations, produced water represents the largest volume by-product, arising from crude oil extraction in both onshore and offshore fields. This water, co-produced with hydrocarbons, typically contains free oil, emulsified oil, suspended solids, dissolved organics, and in many cases high salinity levels that complicate conventional treatment approaches. Flow rates can vary dramatically over the life of a field, from hundreds to tens of thousands of cubic metres per day, placing significant demands on treatment system flexibility and reliability.

Downstream at refineries and petrochemical facilities, wastewater streams include refinery process water, tank bottom water, desalter brine, and API separator effluent. Each stream presents a unique contaminant profile. Refinery process water carries free and emulsified oil, suspended solids, BTEX compounds, phenols, and chemical additives. Desalter brine is characterised by extremely high salinity, elevated temperatures, and concentrated oil and solids loading. Tank bottom water accumulates sludge, heavy oils, and solids during storage tank operations. The common thread across all these streams is the presence of oil in various forms, alongside suspended solids that require effective separation before discharge or reuse.

Regulatory compliance is a critical driver for oil and gas wastewater treatment. In the UK and North Sea region, OSPAR Convention requirements set stringent limits on oil-in-water discharge, typically requiring concentrations below 30 mg/L and increasingly targeting 15 mg/L or lower. The UK Environment Agency issues permits that may impose additional site-specific limits on COD, suspended solids, and priority substances. Internationally, regional discharge limits vary, but the trend consistently moves toward tighter controls. Failure to comply can result in substantial penalties, operational restrictions, and reputational damage, making proven treatment technology essential for every facility.

Wastewater Streams

  • Produced Water: Upstream extraction
  • Refinery Process Water: Midstream/downstream
  • Tank Bottom Water: Storage residuals
  • Desalter Brine: High salinity
  • API Separator Effluent: Polishing required

Key Characteristics

  • Free & emulsified oil
  • High suspended solids
  • BTEX, H2S, phenols
  • Variable flow & loading
  • High salinity (desalter)
Contaminant Profile

Typical Oil & Gas Wastewater Parameters

Representative influent concentrations and achievable removal efficiencies with DAF-based treatment processes.

ParameterTypical RangeDAF Removal Efficiency
Free Oil50 – 500 mg/L95 – 99%
Emulsified Oil20 – 200 mg/L85 – 95%
TSS100 – 1,000 mg/L80 – 92%
BTEX5 – 50 mg/L30 – 50%
H2S1 – 20 mg/L60 – 80% (as precipitate)
COD500 – 3,000 mg/L40 – 55%

Note: Actual removal efficiencies depend on influent characteristics, chemical dosing regime, and process configuration. Higher BTEX and COD removal typically requires downstream advanced biological treatment or activated carbon polishing.

Treatment Process

Integrated DAF Treatment Process

A five-stage process engineered to handle the complex, variable nature of oil and gas wastewater from inlet to compliant effluent.

API/Separator Pre-treatment

Gravity-based API separators or corrugated plate interceptors remove free oil and settle heavy solids. Recovered oil is skimmed and returned to processing. This primary step reduces oil loading on downstream DAF by 60-80%.

pH Adjustment & Breaking

pH is adjusted to the optimal range for coagulation, typically 6.5 – 7.5. Demulsifying agents and acid/breakers destabilise oil emulsions, enabling droplets to coalesce and separate more readily in the DAF cell.

Coagulation/Flocculation

Metal salt coagulants and polyelectrolyte flocculants are dosed in rapid-mix and flocculation chambers. This step aggregates fine oil droplets and suspended solids into larger, buoyant flocs amenable to air flotation.

DAF Flotation

Pressurised recycle water saturated with air is released into the DAF cell, generating micro-bubbles (20-50 microns) that attach to oil and solids flocs. The buoyant sludge blanket is continuously skimmed from the surface.

Polishing Filter

Multimedia or activated carbon filters capture residual oil droplets and dissolved organics missed by flotation. This final polishing step ensures consistent compliance with stringent discharge limits and protects receiving waters.

Design Considerations

Engineering for Oil & Gas Environments

Specialised design features that ensure safe, reliable, and compliant DAF operation in petroleum production and refining facilities.

Explosion-Proof Requirements (ATEX)

Offshore platforms, tank farms, and process areas with volatile hydrocarbons require ATEX-certified electrical components, flameproof enclosures, and intrinsically safe instrumentation. Our skid-mounted DAF units can be supplied with full Zone 1 or Zone 2 compliance.

Corrosion-Resistant Materials

SS316 construction is standard for wetted parts exposed to saline produced water and aggressive refinery chemicals. Duplex stainless steel (2205/2507) is available for high-chloride applications where pitting and stress corrosion cracking are concerns.

High-Pressure Saturator Design

Our saturators operate at 4-6 bar to maximise air dissolution and micro-bubble generation. High-efficiency pall ring packing and automated level control ensure consistent bubble size distribution and flotation performance under variable hydraulic loading.

Oil Sludge Handling & Recovery

DAF float sludge in oil and gas applications contains a high proportion of recoverable hydrocarbons. We design integrated skimming, thickening, and dewatering systems that maximise oil recovery for reprocessing while minimising disposal requirements and costs.

Salinity Effects on Bubble Size

High salinity changes water density and surface tension, affecting micro-bubble formation and rise velocity. Our saturator and nozzle designs are optimised for saline produced water, ensuring consistent flotation kinetics across TDS levels from 1,000 to 200,000 mg/L.

Produced Water vs Refinery Water

Produced water typically has high salinity, lower temperature, and stable flow. Refinery wastewater is more variable, hotter, and contains process chemicals. We tailor DAF design parameters, chemical selection, and materials of construction to match each specific application.

Example Projects

Representative DAF Proposals for Oil & Gas

Realistic project scopes and budgetary estimates based on typical oil and gas wastewater treatment requirements.

Proposal 1: Offshore Platform Produced Water

Project Name: Offshore Platform Produced Water Treatment Upgrade

Flow Rate: 2,000 m³/day (83 m³/hr)

Influent Characteristics: Free oil 150 mg/L, emulsified oil 80 mg/L, TSS 300 mg/L, TDS 45,000 mg/L, temperature 25°C

DAF Model/Size: R&B-DAF-100 (4.2m x 12m x 3.5m H), hydraulic loading 5.5 m/hr

Key Equipment: Skid-mounted DAF with ATEX Zone 1 electricals, duplex SS saturator, automated polymer station, oil sludge thickener, PLC/SCADA panel

Chemical Consumption: Ferric chloride 120 kg/day, anionic polymer 8 kg/day, pH adjustment acid/base 50 kg/day

Performance Targets

  • Effluent Oil: < 15 mg/L
  • Effluent TSS: < 30 mg/L

Proposal 2: Refinery API Effluent Polishing

Project Name: Refinery API Separator Effluent DAF Polishing

Flow Rate: 5,000 m³/day (208 m³/hr)

Influent Characteristics: Free oil 45 mg/L, emulsified oil 120 mg/L, TSS 250 mg/L, COD 850 mg/L, BTEX 25 mg/L, pH 7.2

DAF Model/Size: R&B-DAF-250 (6.5m x 18m x 3.8m H), hydraulic loading 5.0 m/hr

Key Equipment: SS316 DAF with lamella plate pack, chemical dosing station (coagulant + flocculant + pH), automatic sludge removal, effluent oil monitor, DCS integration

Chemical Consumption: PAC 200 kg/day, cationic polymer 15 kg/day, caustic soda 80 kg/day

Performance Targets

  • Effluent Oil: < 10 mg/L
  • Effluent TSS: < 25 mg/L

Proposal 3: Tank Farm Runoff Treatment

Project Name: Crude Storage Tank Farm Stormwater & Drainage

Flow Rate: 300 m³/day (12.5 m³/hr)

Influent Characteristics: Free oil 200 mg/L, emulsified oil 60 mg/L, TSS 400 mg/L, occasional peaks to 1,000 mg/L oil during rainfall, temperature ambient

DAF Model/Size: R&B-DAF-25 (2.0m x 5.5m x 2.8m H), hydraulic loading 4.5 m/hr

Key Equipment: Compact SS316 DAF with 2,000 L equalisation tank, ATEX-rated controls, batch chemical dosing, screw press sludge dewatering, containerised option available

Chemical Consumption: Ferric sulphate 25 kg/day, polymer 2 kg/day

Performance Targets

  • Effluent Oil: < 15 mg/L
  • Effluent TSS: < 35 mg/L
Key Benefits

Why DAF for Oil & Gas Wastewater

Proven advantages that make dissolved air flotation the preferred technology for oil and solids removal in petroleum operations.

Superior Oil Recovery

Achieve effluent oil concentrations below 15 mg/L, with many installations consistently reaching 5-10 mg/L. Recovered oil can be returned to crude or product streams, reducing waste and generating value.

OSPAR & EA Compliance

Meet and exceed UK Environment Agency permit conditions and OSPAR discharge limits. Our DAF systems are designed with regulatory margins to accommodate influent variability without breaching consent.

Reduced Injection Well Disposal

By treating produced water to discharge quality, operators can reduce costly disposal to injection wells. This extends reservoir life, lowers operating overheads, and improves overall field feasibility.

Compact Offshore Footprint

High-rate DAF technology achieves separation in a fraction of the footprint required by conventional gravity separators. Skid-mounted packages simplify installation on crowded offshore platforms and FPSOs.

ATEX Certified Options

Full hazardous area compliance with ATEX-certified electrical panels, flameproof motors, and intrinsically safe instrumentation. Safety is engineered into every component for operation in explosive atmospheres.

API Separator Integration

Seamlessly retrofit downstream of existing API separators to polish effluent and achieve modern discharge standards without replacing proven primary separation infrastructure.

Engineering Detail

Oil & Gas DAF — Design Parameters

DAF in oil & gas covers produced water, refinery effluent, drilling-mud water and tank-bottoms water.

Oil-in-Water Target

OSPAR overboard: <30 mg/L. UK ELG: <30 mg/L. RB DAF achieves <10 mg/L with coagulant aid. Polish with walnut-shell filter for <5 mg/L injection-water quality.

Emulsified Oil Breaking

Stable emulsions need chemical demulsification: cationic polyamines 5–25 mg/L. Heat (50–70°C) accelerates breaking. Choose chemistry to suit oil API and salinity.

ATEX Hazardous Area

All wetted electrical equipment Zone 1/2 certified IECEx/ATEX. Sealed motors, intrinsically-safe sensors, vapour-tight skid covers. Inert blanket on saturator vapour space.

Materials

Duplex 2205 for chloride-rich produced water. 316L for refinery process effluent. Coated CS for hydrocarbon-only streams. CuNi for seawater service.

Compact Footprint

Offshore: CFU configuration with internal coalescence and gas flotation in one vessel. Footprint 30–50% of equivalent atmospheric DAF.

Solids Handling

Sand and scale from oil-gas streams. DAF requires bottom-sand removal hopper or upstream desander. Pumped slurry to dewatering / disposal.

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Speak to Our Engineers

Discuss your specific requirements with our technical team and receive a tailored proposal for your project.

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Industries We Serve

Our expertise spans multiple industries with sector-specific water treatment solutions.

Food Processing Poultry Processing Meat Processing Dairy Industry Brewery & Beverage Municipal Wastewater Industrial Pre-treatment Desalination Plants Metro & Tunnelling Pharmaceutical Manufacturing Oil & Gas Industry Mining & Minerals Chemical Processing Pulp & Paper Mills Power Generation Textile Manufacturing Storage Tanks Process Tanks