Refinery water-treatment plant at dusk
Filtration & Treatment Technologies

The full spectrum of water-treatment technology for oil, gas & petrochemicals

From bulk gravity separation to membrane desalination and advanced oxidation, WFS engineers, builds and operates every unit operation in the modern treatment train — custom-designed to your water and your target specification.

23
Core technologies
4
Treatment stages
1
End-to-end partner
5
Global offices
Introduction

One treatment train, engineered from the right unit operations

No single technology treats every contaminant. Oil appears as free, dispersed and emulsified fractions; water also carries suspended solids, dissolved salts, organics (COD), dissolved gases such as H₂S and ammonia, and micro-organisms — each demanding a different separation or destruction mechanism.

WFS approaches each application as an engineering problem: characterize the water, select the right unit operations, and assemble them into a custom train that reliably meets the discharge, reuse or zero-liquid-discharge objective. The technologies below are the building blocks — organised by the treatment stage at which they act.

PRIMARY

Bulk phase separation — free oil, gross solids, grit.

SECONDARY

Emulsified oil, fine solids and stabilised colloids.

TERTIARY

Dissolved salts, organics, gases — membrane, ion & stripping.

POLISHING

Refractory organics, micro-pollutants, disinfection, biology.

3 Primary · 7 Secondary · 7 Tertiary · 6 Polishing technologies

Technology Library

23 technologies — each with its own engineering page

Select any technology for the underlying science, working mechanism, efficiency, operating parameters, a system schematic, typical specifications and target applications.

API SeparatorPRIMARY

API Separator

API

Gravity-based rectangular basin that separates bulk free oil, settleable solids and water by density difference — the robust first stage of nearly every oily-water train.

Explore technology →
Corrugated Plate InterceptorPRIMARY

Corrugated Plate Interceptor

CPI

Inclined corrugated-plate pack that shortens the distance an oil droplet must rise — delivering API-class separation in a fraction of the footprint.

Explore technology →
HydrocyclonesPRIMARY

Hydrocyclones

HC

Static centrifugal de-oilers that spin produced water at thousands of g — separating dispersed oil with no moving parts in a compact, deck-friendly package.

Explore technology →
Dissolved Air FlotationSECONDARY

Dissolved Air Flotation

DAF

Micro-bubble flotation that lifts emulsified oil, light solids and chemical floc to the surface — the workhorse secondary de-oiler for emulsified streams.

Explore technology →
Multimedia FiltrationSECONDARY

Multimedia Filtration

MMF

Layered anthracite–sand–garnet beds that strain residual suspended solids and oil to protect membranes and ion exchange downstream.

Explore technology →
Walnut Shell FiltersSECONDARY

Walnut Shell Filters

WSF

Deep-bed crushed-walnut-shell media with a natural affinity for oil — the produced-water polishing filter that scrubs clean and recovers full capacity.

Explore technology →
CoalescersSECONDARY

Coalescers

COAL

High-surface-area media that merge fine dispersed oil droplets into large, easily separated drops — a low-pressure-drop enhancer for gravity de-oiling.

Explore technology →
Bag FiltersSECONDARY

Bag Filters

BAG

Replaceable fabric bags in pressure housings for low-cost, high-flow removal of coarse suspended solids — simple frontline particulate protection.

Explore technology →
Cartridge FiltersSECONDARY

Cartridge Filters

CART

Pleated or wound elements with absolute micron ratings — the final guard filter that protects RO membranes and high-purity systems.

Explore technology →
ElectrocoagulationSECONDARY

Electrocoagulation

EC

Electrically dosed coagulation that breaks the toughest stable emulsions and precipitates heavy metals — without bulk chemical addition.

Explore technology →
UltrafiltrationTERTIARY

Ultrafiltration

UF

Pressure-driven membranes (0.01–0.1 µm) that deliver an absolute barrier to suspended solids, oil, bacteria and viruses — the modern RO pre-treatment standard.

Explore technology →
NanofiltrationTERTIARY

Nanofiltration

NF

Loose membranes (0.001–0.01 µm) that selectively reject divalent ions, hardness, colour and micro-pollutants while passing much of the monovalent salt.

Explore technology →
Reverse OsmosisTERTIARY

Reverse Osmosis

RO

High-pressure semi-permeable membranes that reject dissolved salts and organics to produce near-pure permeate — the backbone of desalination, reuse and ZLD.

Explore technology →
Ion ExchangeTERTIARY

Ion Exchange

IX

Selective resin beds that swap unwanted ions for benign ones — delivering softening, demineralisation and trace heavy-metal capture to ultra-low levels.

Explore technology →
Sour Water StrippersTERTIARY

Sour Water Strippers

SWS

Steam-stripping columns that drive dissolved H₂S and ammonia out of refinery sour water — recovering acid gas for the sulphur plant and protecting downstream treatment.

Explore technology →
Wet ScrubbersTERTIARY

Wet Scrubbers

WS

Gas–liquid contact towers that neutralise sour and acid gases and capture particulate — bridging water treatment and emissions control for stripped-gas and vent streams.

Explore technology →
Activated Carbon AdsorptionTERTIARY

Activated Carbon Adsorption

GAC

High-surface-area carbon that adsorbs trace hydrocarbons, BTEX, colour and refractory organics — the broad-spectrum organic polishing stage.

Explore technology →
Chlorine Dioxide (ClO₂) TreatmentPOLISHING

Chlorine Dioxide (ClO₂) Treatment

ClO₂

A powerful selective oxidant and biocide dosed on-site — controls biofouling and oxidises sulphides without forming chlorinated by-products.

Explore technology →
Advanced Oxidation ProcessesPOLISHING

Advanced Oxidation Processes

AOP

Hydroxyl-radical generation (UV/ozone/peroxide/Fenton) that destroys the most persistent organics outright — mineralising what other processes only transfer.

Explore technology →
Electro-oxidationPOLISHING

Electro-oxidation

EO

Direct anodic oxidation at dimensionally stable electrodes that destroys refractory organics and ammonia in high-salinity brines — chemical-free advanced oxidation.

Explore technology →
PhotocatalysisPOLISHING

Photocatalysis

PC

UV-activated semiconductor catalysts (TiO₂) that generate reactive radicals from light — a green advanced-oxidation route that breaks down complex organics.

Explore technology →
Sequencing Batch ReactorPOLISHING

Sequencing Batch Reactor

SBR

A fill-and-draw activated-sludge process that performs equalisation, biological oxidation and clarification in one tank — compact, flexible biological polishing.

Explore technology →
Moving Bed Biofilm ReactorPOLISHING

Moving Bed Biofilm Reactor

MBBR

Continuous biofilm process on floating plastic carriers — high biomass, small footprint and strong resilience to toxic and load shocks.

Explore technology →
Comparison

Classification, specifications, advantages & limitations

How each technology is classified, what it does, and where it excels or falls short — the engineer's shortlist at a glance.

TechnologyClassSpecificationsAdvantagesLimitations
API SeparatorPRIMARYGravity-based, rectangular basins for bulk phase separation.Low cost, robust, handles massive flow rates and slugs.Large footprint; ineffective on emulsified oil fractions.
Corrugated Plate InterceptorPRIMARYGravity-based with inclined plates to reduce settling distance.Small footprint; significantly higher efficiency than API.Susceptible to clogging from heavy solids; plates require chemical washing.
HydrocyclonesPRIMARYCentrifugal force, high pressure-drop liquid–liquid / solid separation.Extremely compact, no moving parts, efficient on concentrated streams.Very sensitive to feed flow and pressure; high shear risk.
Dissolved Air FlotationSECONDARYMicro-air bubbles attach to suspended matter to float it to surface.Excellent for emulsified oil and light colloidal solids.Chemical-intensive; produces wet sludge scum.
Multimedia FiltrationSECONDARYFixed-bed multi-layered filtration (anthracite / sand / gravel).Handles high solids loading; reliable; low operating cost.Frequent backwashing; media can be permanently fouled by oil.
Walnut Shell FiltersSECONDARYDeep-bed media filtration using crushed walnut shells.Excellent oil affinity; easily cleaned by vigorous backwashing.Requires periodic mechanical attrition and media make-up.
CoalescersSECONDARYHigh-surface-area mesh / packing for oil-droplet growth.Low pressure drop; highly effective at coalescing micro-droplets.High fouling risk with high solids or surfactants.
Bag FiltersSECONDARYReplaceable fabric bags in pressure vessels; nominal filtration.Low capital cost; easy manual replacement; good for coarse solids.Manual batch replacement; high running cost under heavy solids.
Cartridge FiltersSECONDARYReplaceable pleated or wound elements; absolute micron rating.Precise absolute filtration; ideal downstream-membrane protection.Non-cleanable elements; costly as a primary filter.
ElectrocoagulationSECONDARYSacrificial anodes (Al/Fe) release ions via current to destabilise emulsions.Removes stable emulsions and metals with minimal chemical dosing.Anode passivation and plate replacement; high power use.
UltrafiltrationTERTIARYPressure-driven membrane separation (0.01 – 0.1 µm).Excellent removal of macromolecules, viruses, bacteria, fine colloids.Surface fouling; requires regular chemical cleaning.
NanofiltrationTERTIARYPressure-driven membrane separation (0.001 – 0.01 µm).Removes divalent ions, pesticides and colour molecules.High pressure; scaling risk from hardness/sulphate.
Reverse OsmosisTERTIARYHigh-pressure semi-permeable membrane overcoming osmotic pressure.Near-pure permeate; reliable desalter and reuse feed.High energy; produces concentrated brine reject.
Ion ExchangeTERTIARYSynthetic resin beads exchange target ionic species.Highly selective; achieves ultra-low dissolved-metal concentrations.Needs chemical regenerants; creates hazardous waste stream.
Sour Water StrippersTERTIARYSteam-stripping columns to remove dissolved H₂S and NH₃.Efficient acid-gas recovery for sulphur-plant feed.High steam demand; corrosive duty needs premium alloys.
Wet ScrubbersTERTIARYGas–liquid contact towers with packing or sprays to neutralise sour gases.High removal of acid gases and volatile particulate.Generates a contaminated blowdown needing separate treatment.
Activated Carbon AdsorptionTERTIARYGranular or powdered high-surface-area activated carbon media.Broad-spectrum organic removal; excellent for trace hydrocarbons/BTEX.Media exhaustion needs reactivation or replacement; costly.
Chlorine Dioxide (ClO₂) TreatmentPOLISHINGSelective chemical oxidant dosed directly into water streams.Highly effective biocide with no chlorinated by-products.Corrosive gas; needs precise on-site generation and dosing.
Advanced Oxidation ProcessesPOLISHINGHydroxyl-radical (•OH) generation via UV/ozone, H₂O₂ or Fenton.Destroys persistent organics rather than transferring phases.High operating cost from chemicals and electrical power.
Electro-oxidationPOLISHINGDirect electrolytic oxidation at dimensionally stable anodes (DSA).Destroys refractory organics and ammonia in high-salinity brines.High power use; costly specialised coated electrodes.
PhotocatalysisPOLISHINGUV-activated semiconductor catalysts (e.g. TiO₂) generating radicals.Green technology using UV/ambient light; breaks complex organics.Low quantum efficiency; catalyst fouling and separation issues.
Sequencing Batch ReactorPOLISHINGFill-and-draw cyclic activated-sludge system.Combines equalisation, aeration and clarification in one basin.Batch operation needs complex automation and equalisation.
Moving Bed Biofilm ReactorPOLISHINGContinuous biological process using floating high-surface-area carriers.High biomass, compact footprint, resilient to toxic shock loads.Needs downstream clarification/screening to retain carrier fragments.
Contaminant Removal Matrix

What each technology removes

Relative removal performance by contaminant class.NoneLowMediumHigh
TechnologyFree Oil >150µmEmulsified OilSuspended SolidsDissolved SolidsOrganics / CODDissolved GasesMicrobials
API SeparatorHighNoneMediumNoneLowNoneNone
Corrugated Plate InterceptorHighLowMediumNoneLowNoneNone
HydrocyclonesHighMediumMediumNoneLowNoneNone
Dissolved Air FlotationMediumHighHighNoneLowNoneLow
Multimedia FiltrationLowMediumHighNoneLowNoneLow
Walnut Shell FiltersMediumHighHighNoneMediumNoneNone
CoalescersMediumHighLowNoneMediumNoneNone
Bag FiltersMediumLowHighNoneNoneNoneLow
Cartridge FiltersLowLowHighNoneNoneNoneMedium
ElectrocoagulationMediumHighHighLowMediumNoneMedium
UltrafiltrationLowMediumHighLowMediumNoneHigh
NanofiltrationNoneLowHighMediumHighNoneHigh
Reverse OsmosisNoneNoneLowHighHighNoneHigh
Ion ExchangeNoneNoneNoneHighLowNoneNone
Sour Water StrippersNoneNoneNoneNoneLowHighNone
Wet ScrubbersNoneNoneHighNoneLowHighNone
Activated CarbonLowMediumLowLowHighLowLow
Chlorine Dioxide (ClO₂)NoneNoneNoneNoneLowLowHigh
Advanced Oxidation ProcessesNoneNoneNoneNoneHighLowMedium
Electro-oxidationNoneLowNoneNoneHighMediumHigh
PhotocatalysisNoneLowNoneNoneHighLowMedium
Sequencing Batch ReactorNoneLowMediumNoneHighLowLow
Moving Bed Biofilm ReactorNoneLowMediumNoneHighLowLow
The WFS Lifecycle

A single partner for the entire water-treatment lifecycle

Every technology can be delivered as a stand-alone system, as part of a complete treatment plant, or as a retrofit to an existing plant — and WFS owns every step.

1

Study & Characterize

We study the application and characterize the water — lab analysis and 24-hour composite sampling across normal, upset and turnaround operation.

2

Custom Design

We custom-design a complete treatment train for each application — selecting and sequencing the right unit operations to the target specification.

3

Pilot & Trial

We pilot and trial the design on-site where required, confirming performance on the real stream before any equipment is sized.

4

Detailed Engineering

Full detailed engineering and equipment design of every unit in the treatment train.

5

Fabricate & Deliver

We fabricate the equipment, deliver the system to site and construct the treatment plant with all process connections.

6

Install & Automate

We install the electrical connections and integrate automation through instrumentation and controls.

7

Continuous O&M

We perform continuous operations & maintenance, sustaining guaranteed performance over the asset life.

Share your stream data and target specification

WFS will characterize the water and propose a custom train — stand-alone, complete plant, or retrofit to your existing system.

Get a Cost-to-Treat Estimate

Share your water chemistry, flow rate and discharge spec — our engineers scope a treatment train and return a tailored, confidential estimate for your site.