Oil/water separation experts, API separators, DAF, coalescers, and membranes for free, emulsified, and dissolved oil.

    Find a Oil & Grease Removal Provider

    Matched providers: 37

    Top countries: United Kingdom, United States

    Popular technologies: Flat Sheet UF Membranes, Hollow Fiber RO

    Oil and Grease Removal from Water: DAF, API Separators, and Coalescing Plate Interceptors

    Oil and grease (O&G) in industrial wastewater includes free oil (droplets above 150 microns, easily settled or floated), dispersed oil (droplets 20 to 150 microns, requiring coalescing or flotation), emulsified oil (droplets below 20 microns stabilised by surfactants, requiring chemical emulsion-breaking), and dissolved hydrocarbons (require biological or activated carbon treatment).

    US EPA effluent guidelines specify O&G limits by industry: offshore oil and gas 29 mg per L (30-day average); petroleum refining 9.9 mg per L (30-day average, 40 CFR Part 419); and food processing varies by product. EU IED BAT-AEL for refineries: 1 to 5 mg per L O&G in treated effluent. Environment Agency UK trade effluent consent typical limit: 5 to 30 mg per L O&G.

    API (American Petroleum Institute) oil-water separators (API 421) use gravity separation for free oil removal: rectangular vessel with 30 to 60-minute HRT, horizontal flow velocity below 0.003 m per s (to prevent turbulence resuspending settled solids), surface loading 1.5 to 3.0 m3 per m2 per hour, oil collection by skimmer. API separators remove droplets above 150 microns at 90 percent efficiency.

    Coalescing plate interceptors (CPI, parallel plate or corrugated pack media) enhance API performance: plates at 45 degrees (chevron) with 15 to 50 mm spacing provide enhanced surface area for droplet coalescence and collection, removing droplets above 50 to 60 microns at 90 percent efficiency within a fraction of the footprint of an API separator. Dissolved Air Flotation (DAF) generates 20 to 80 micron bubbles (by dissolving air at 4 to 6 bar and releasing at atmospheric pressure) that attach to oil droplets and float them to the surface; removes droplets above 10 to 20 microns at greater than 95 percent efficiency.

    Chemical demulsification is required for stabilised oil-water emulsions (O/W emulsions from cooling lubricants, cutting oils, metal working fluids, food processing). Emulsion-breaking chemicals (cationic coagulants: polyDADMAC, Al/Fe salts; pH adjustment to ISO point of emulsifying agent; acid cracking of soap-type emulsifiers at pH 2 to 3) destabilise the emulsion and allow the oil phase to coalesce and separate.

    Acid cracking: adjust pH to 2 to 3 with H2SO4, heat to 50 to 70 degrees C, settle or DAF. Coagulation-based breaking: add 200 to 500 mg per L alum or ferric at pH 6 to 8, 2 to 5 minutes rapid mix, 15 to 20 minutes flocculation, then DAF removes floated oil-sludge complex. Ultrafiltration (UF) or microfiltration is an emerging replacement for chemical demulsification in cutting oil treatment, avoiding chemical waste.

    Frequently Asked Questions

    What is the difference between an API separator and a DAF unit for oil removal?

    An API oil-water separator (API 421) uses gravity separation alone: oil rises to the surface (density difference) in a quiescent chamber, removed by skimmer; heavy solids settle to floor and are removed by scraper. Effective for free oil above 150 microns. Simple, low-cost, no chemicals needed. Limitations: large footprint (30 to 60 min HRT), ineffective for dispersed or emulsified oil below 150 microns. Dissolved Air Flotation (DAF) uses micro-bubbles (20 to 80 microns diameter, generated by air dissolution under pressure) that adhere to oil droplets and float them rapidly to the surface as a froth layer, removed by skimmer paddle. Effective for oil droplets above 10 to 20 microns. Chemical coagulant and flocculant addition (10 to 50 mg per L FeCl3 plus 1 to 5 mg per L polyelectrolyte) improves emulsified oil removal by breaking the emulsion before flotation. DAF achieves 95 to 99 percent O&G removal in a compact footprint (HRT 15 to 30 minutes). Capital cost: API separator $20,000 to $200,000; DAF $50,000 to $500,000.

    What are the discharge limits for oil and grease in industrial wastewater?

    US EPA effluent guidelines (sector-specific): oil and gas extraction (offshore): 29 mg per L monthly average total O&G (40 CFR Part 435); petroleum refining: 9.9 mg per L (30-day average), 15 mg per L (daily maximum) total O&G (40 CFR Part 419); food processing (meat, poultry): 10 mg per L (40 CFR Part 432); metal finishing: no explicit O&G limit but TSS and pH limits indirectly control emulsified oil. EU Industrial Emissions Directive (2010/75/EU) BAT-AEL for refineries: 1 to 5 mg per L O&G in treated effluent per BAT Conclusions published 2015. UK Environment Agency: site-specific consent limits typically 5 to 30 mg per L total O&G for discharge to sewer; 5 to 10 mg per L for direct discharge to surface water. Petroleum-contaminated stormwater from petrol station forecourts: EN 858-1 Class 1 separator required (effluent below 5 mg per L free oil).

    How is emulsified oil removed from wastewater?

    Emulsified oil (droplets below 20 microns stabilised by surfactants or mechanical emulsification) requires chemical or physical emulsion breaking before separation. Methods: (1) Acid cracking: reduce pH to 2 to 3 with H2SO4 (breaks soap-type emulsifiers by protonating carboxylate surfactants); heat to 60 to 80 degrees C to accelerate coalescence; settle or DAF to separate broken emulsion. Cost-effective for high-pH, soap-emulsified cutting fluid waste. (2) Coagulation: add alum (200 to 500 mg per L) or polyDADMAC (10 to 50 mg per L) to neutralise surface charge on oil droplets, allowing coagulation and DAF removal. Achieves O&G below 10 mg per L. (3) Ultrafiltration (UF, 0.01 to 0.1 micron): rejects oil droplets mechanically regardless of emulsion type; effective for waste cutting oils and coolants; permeate at below 10 mg per L O&G; generates concentrated reject (10 to 30 percent oil content) requiring further disposal. (4) Biological treatment: dissolved and emulsified hydrocarbons are biodegradable; activated sludge or biofilm systems after physical oil removal achieve effluent O&G below 5 mg per L.

    Can oil recovered from wastewater be reused?

    Oil recovery and reuse feasibility depends on oil purity and concentration. High-purity free oil skimmed from API separators at petroleum facilities: can be returned to the refinery crude oil feed or sold as slop oil at $150 to $400 per tonne (well below crude oil price due to water content and contamination). Edible oil recovered from food processing wastewater (DAF float): subject to food safety regulations, cannot be returned to food production; may be used as animal feed ingredient if clean, or as biodiesel feedstock. Mineral oil from metal working coolant waste: concentrated waste coolant (5 to 30 percent oil) from UF treatment can be burned as a fuel in cement kilns or co-fired industrial boilers under waste fuel permit conditions. Oil-water mixture skimmings from refinery API separators (3 to 10 percent oil): typically mixed with crude oil or burned as fuel. Recovery economics improve when oil commodity price is high; at oil prices below $50 per barrel, recovery from wastewater may be net-cost neutral versus disposal.

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    Oil & Grease Removal Companies

    Oil/water separation experts, API separators, DAF, coalescers, and membranes for free, emulsified, and dissolved oil.

    16 specialist providers · 21 related · 12 countries

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    Specialists in oil & grease removal

    Providers whose services or self-declared specialties match this category.

    ALAR Corp

    United States

    ALAR Corp manufactures industrial wastewater treatment systems addressing compliance, hauling costs, and regulatory requirements. The company designs and builds equipment for diverse industries including food and beverage, concrete, surface finishing, and oily wastewater applications.

    Industrial wastewater treatment system designDischarge compliance solutionsSludge dewatering services
    MW

    MITA Water Technologies

    Italy

    MITA Water Technologies, founded in 1971 in Siziano near Pavia, Italy, designs wastewater treatment equipment with deep expertise in cloth filtration and physical separation. Its Oilpack lamella-pack oil separators and Mitadaf dissolved air flotation units target oil and grease removal, while pile cloth filters, Filtrasand sand filters and Biorulli biological disc rotors handle tertiary filtration, suspended solids and BOD/COD reduction for reuse. Part of Axius Water, the firm offers pilot testing, start-up, revamping and remote monitoring.

    Equipment design and supplyPilot testingStart-up and training

    Sodai

    Italy

    Sodai is a Milan, Italy environmental engineering company with more than 30 years of experience in purifying and treating primary waters and industrial process fluids. It designs and operates tailor-made and standard plants for desalination, potabilization, purification, oily water treatment, water reuse and zero liquid discharge, serving Oil, Gas and Power clients including operating centers for ENI and ENEL. The company works across 28 countries and holds ISO 9001, ISO 14001 and ISO 45001 certification.

    Tailor-made plant designStandard plant supplyPlant management and maintenance
    EE

    Ecologix Environmental Systems

    United States

    Ecologix Environmental Systems is a United States provider of industrial water and wastewater treatment solutions with over 20 years of experience. It supplies full-scale treatment plants and components including dissolved air flotation, MBBR and MBR systems, oil-water separators and reverse osmosis, plus engineering, installation, treatability studies and financing.

    Industrial wastewater treatmentSludge dewateringEngineering and installation
    AC

    Advanced Chemical Systems

    United States

    Advanced Chemical Systems, Inc. (ACS) is a water and wastewater treatment company headquartered in Franklin, Wisconsin. Founded in 1977, ACS provides custom chemical and equipment solutions for industrial wastewater treatment across a wide range of facilities and applications, including boilers, cooling towers, plating, parts washing, and machining processes. The company combines treatment chemistry with equipment, water sample analysis, compliance consulting, and staff training to help industrial sites meet discharge and process water quality requirements.

    Industrial wastewater treatment solutionsBoiler and cooling water treatmentWater sample analysis and monitoring
    CE

    Condorchem Enviro Solutions

    Spain

    Condorchem Enviro Solutions is a Catalan environmental engineering firm in Spain providing turnkey industrial wastewater and air emission treatment. Its portfolio spans ENVIDEST vacuum evaporators, DESALT crystallizers, reverse osmosis, ion exchange and activated carbon for zero liquid discharge, oily water treatment, textile and dye color removal, brine management and water reuse. The company holds ISO 9001, ISO 14001 and EcoVadis Gold, covering pollutant analysis, plant design, installation, start-up and after-sales maintenance.

    Turnkey plant designPollutant analysisPlant installation and start-up
    E

    Ecofario

    Germany

    Ecofario, founded in 2013 and headquartered in Munich, Germany, develops filterless microplastic removal technology for municipal and industrial wastewater treatment plants. Its High-G-Separator uses a high-gravity hydrocyclone principle to remove up to 99.9 percent of microplastics, including adhering pollutants, without filter media, and also serves contaminant rejection, oil extraction and fiber-loss reduction. The company partnered with Valmet for automation and was named one of Germany's most sustainable startups in the Resources category.

    Microplastic separation systemsWastewater plant retrofitsHydrocyclone integration

    Fluence

    United States

    Fluence develops modular water and wastewater treatment solutions for municipal, industrial, and decentralized applications. The company offers containerized systems engineered for operational efficiency and rapid deployment, serving diverse sectors including food and beverage, desalination, and waste-to-energy.

    Municipal water and wastewater treatmentIndustrial water treatment and desalinationWater reuse and recycling solutions

    Oil Skimmers, Inc.

    United States

    Oil Skimmers, Inc., headquartered in Cleveland, Ohio and operating for over 50 years, manufactures oil removal equipment that separates oil, fat and grease from process water, wash water, coolant and wastewater. Its Brill tube-type skimmers, floating weir skimmers and oil water separators with Active Oil Removal recover up to 99 percent of free-floating oils across food processing, metal machining, petrochemical and marine sectors. Product lines include CoolSkim, Skim 1st Tank, OilyBelt and the ORTS oil removal and transfer system.

    Oil skimmer manufacturingCustom-engineered separatorsFactory repair and maintenance
    DP

    Depur Padana Acque

    Italy

    Depur Padana Acque is an Italian company with over 50 years in industrial wastewater treatment, serving industrial and agri-food sectors. It designs, installs and maintains purification systems including membrane bioreactors, oil and grease removal, stormwater treatment and biological treatment, offering plant revamping, treatment chemicals and round-the-clock technical assistance.

    Wastewater plant design and engineeringPlant maintenance and revampingTreatment chemicals supply

    Brine Consulting

    Verified

    Netherlands · 1-50 employees

    BRINE CONSULTING delivers senior-level strategy, technical design, and actionable insight across the full lifecycle of water-related challenges. We support clients with advisory and due diligence, advanced brine management and resource recovery, industrial and municipal water reuse, and MLD/ZLD systems. Our team also leads ESG and climate-resilience strategy, innovation scouting, and international development and PPP advisory. With deep specialization in desalination, brine valorization, circular economy models, and high-impact infrastructure, we help organizations turn water and waste streams into opportunities, providing clear thinking, rapid delivery, and solutions built for real-world results.

    Activated Carbon FiltrationReverse Osmosis (RO) SystemsUltrafiltration (UF) Systems

    EC Solutions

    Verified

    United Arab Emirates · freelance

    EC Solutions is a specialized consultancy focused on electrochemical technologies for water and wastewater treatment. We believe electrochemical processes, and electrocoagulation in particular, are among the most promising technologies in the water sector today. As a rule of thumb, anything that can be treated with conventional coagulation–flocculation can be pretreated with electrocoagulation, without adding chemicals. That means less chemical handling, lower sludge complexity, and more controllable treatment outcomes. We help industries evaluate, pilot, and implement electrocoagulation as a robust pretreatment or core process for color removal, heavy metals, TSS, emulsified oils, and complex industrial effluents. If you’re dealing with a difficult water challenge and want a cleaner, smarter alternative to chemical treatment, EC Solutions is built for that.

    Greywater Recycling SystemsIndustrial Process Water ReuseIndustrial Wastewater Treatment Plants

    Ecosystems International

    Verified

    Indonesia · 51-200 employees

    PT Ecosystems International (PT ESI) was established at Jakarta on 21st November 2006. We are an industrial effluent treatment systems integrator specializing in electrocoagulation (EC), a unique waste water treatment profile. PT ESI has capabilities in designing complete waste water treatment solutions by combining various effluent treatment systems such as the electro-coagulation, biological, chemical processes and membrane filtration, offering its customers a wide and comprehensive range of solutions, tailored to suit their various needs – ranging from basic effluent treatment for discharge to effluent recycling for water reuse. The Company is experienced in handling the design, engineering, procurement, construction and operation of new Effluent Treatment Plants (“ETP”) and possesses expertise in retrofitting existing ETP to increase the flow rate and treatment capability without any major infrastructure increase PT ESI is also a premier waste water treatment service company specializing in handling waste water generated from Exploration (Drilling) and Produced Water. Customers in Indonesia include major Oil & Gas companies such as Pertamina, Exxon, Chevron, Petro-China and Medco. Operations in Indonesia are provided by both mobile and fixed units. At drill sites where waste-water recycling is required, PT ESI supplement these treatment units with skid mounted mobile Reverse Osmosis systems. The technologies and solutions employed by PT ESI are developed in-house and examples of these are its proprietary Trident™ Electro Contaminant Removal (“ECR”) system, the Stage Contaminant Removal (“SCR”) process and Mobile On-Site Waste-Water Treatment (“OWT”) units

    Reverse Osmosis (RO) SystemsUltrafiltration (UF) SystemsMulti-media Filtration (MMF) Systems

    Devram International

    Verified

    India · 1-50 employees

    DEVRAM INTERNATIONAL, headquartered in Surat, India, is a pioneering enterprise specializing in Snow and Rainwater Management with advanced contamination reduction abilities for storage and artificial groundwater recharge. Established as the commercial wing of Shree Someshwar Education Trust (SSET), DEVRAM INTERNATIONAL is driven by a mission to provide tech-enabled, nature-based solutions that address the world’s most pressing water and climate challenges. The company’s work integrates Integrated Water Resources Management (IWRM) principles and contributes across the source-to-sea water management cycle, ensuring holistic restoration of the global water cycle. Its innovative portfolio includes rainwater harvesting systems, stormwater management, aquifer recharge, artificial glaciers, desert trenches, rooftop water filtration, and green infrastructure models. These interventions directly reduce salinity in soils and aquifers, restore ecological balance, and enhance resilience to droughts, floods, and climate change. As the commercial promoter of the Global Rainwater Management Program (GRMP), DEVRAM INTERNATIONAL advances the vision of GRMP as a Global Common Minimum Program (GCMP) for nations and international bodies. GRMP demonstrates how rainwater and snowwater retention can restore entire natural cycles, while delivering unmatched benefits across the Sustainable Development Goals (SDGs). Alignment with the SDGs • SDG 2 (Zero Hunger): By reducing soil salinity, supporting organic farming, and ensuring water availability for agriculture, GRMP safeguards food security. • SDG 6 (Clean Water & Sanitation): DEVRAM’s recharge structures and contamination reduction technologies guarantee safe, sustainable drinking water for communities. • SDG 7 (Affordable & Clean Energy): By reducing dependency on energy-intensive desalination, GRMP lowers national energy bills and improves hydropower capacity. • SDG 9 (Industry, Innovation & Infrastructure): DEVRAM integrates nature-based water infrastructure with industrial operations, reducing OPEX and water footprints. • SDG 11 (Sustainable Cities & Communities): Through stormwater management and aquifer recharge, GRMP mitigates urban flooding and secures municipal supplies. • SDG 12 (Responsible Consumption & Production): Promotes a circular water economy, reusing wastewater, biogas from organic waste, and aligning with industrial CSR. • SDG 13 (Climate Action): By lowering GHG emissions and cooling local climates through water cycle restoration, GRMP strengthens resilience to global warming. • SDG 14 (Life Below Water): Free-flowing rivers, improved aquaculture, and reduced dam-related aquatic pollution support marine and freshwater ecosystems. • SDG 15 (Life on Land): DEVRAM’s interventions restore wetlands, mangroves, peatlands, and biodiversity-rich ecosystems, addressing land degradation. • SDG 17 (Partnerships for the Goals): The company actively collaborates with UN agencies, governments, World Bank programs, and private investors to scale GRMP globally. Founders and Leadership Dhaval Pandya, Co-Founder of DEVRAM INTERNATIONAL and CEO of SSET, is a globally recognized sustainability leader. He co-developed the Global Rainwater Management Program (GRMP), recognized by the United Nations Global Water Partnership (GWP) and the Government of India. As a Technical Committee Member (WRD03) of the Bureau of Indian Standards (BIS), he contributes to national water policy frameworks. His work is featured in UNCCD IWRM Action Hub and global forums like COP, Stockholm World Water Week, and World Bank SDG reviews. Manalika Pandya, Co-Founder, plays a critical role in embedding social, gender, and educational dimensions into GRMP. Her focus on women empowerment, local capacity building, and community-driven adoption ensures the program’s sustainability at the grassroots. Impact and Recognition DEVRAM INTERNATIONAL has piloted groundbreaking projects such as: Kawas Village (Gujarat, India): A GRMP model village achieving self-reliance in water, organic farming, and biogas, while resolving conflicts with industries. Delhi’s Water Paradox (Figshare Study): Shows how GRMP can solve megacity water crises without costly desalination or dams. GSECL Surat Project: Demonstrates reduced industrial water costs through GRMP recharge planning, aligning profitability with SDG and ESG goals. These projects show GRMP’s potential to reduce industrial and municipal water supply costs by up 60%, avoid massive investments in desalination and dams, and enable nations to achieve water sovereignty. Core Competencies • Rainwater & Snowwater Harvesting • Artificial Groundwater Recharge & Salinity Reduction • Stormwater Management & Urban Flood Control • Transboundary Water Cooperation • IWRM & Source-to-Sea Water Governance • AI-Enabled Hydrological Modelling & Policy Analytics • Environmental Services Restoration (Wetlands, Mangroves, Peatlands) • Circular Economy.

    Activated Carbon FiltrationGranular Activated Carbon (GAC) FiltersMulti-media Filtration (MMF) Systems

    Hainan Litree Water Purification Technology Industry Co., Ltd.

    Verified

    China · 200+ employees

    Litree: Pioneering Ultrafiltration for a Water-Secure World Founded in 1992, Litree has dedicated 30+ years to redefining water purification through ultrafiltration (UF) membrane technology—our core expertise and passion立升(Litree). As a global high-tech enterprise rooted in independent innovation, we’ve evolved from a membrane R&D startup to one of the world’s leading water problem solvers, with over 146 core patents and state-of-the-art manufacturing hubs in Haikou and Suzhou, China立升(Litree). Our signature hollow fiber UF membranes are engineered to deliver unmatched performance: 0.01μm precision removes 99.99% of bacteria, viruses, and contaminants while preserving essential minerals—striking the perfect balance between purity and health立升(Litree). This technology powers our diverse solutions, from residential whole-house systems to large-scale municipal projects and industrial wastewater treatment, all designed for sustainability and cost-efficiency. What truly sets us apart is our commitment to making safe water accessible. We’ve completed projects serving 50,000+ residents with centralized purification systems that cut construction costs and footprint by 50% compared to traditional setups—proof that advanced technology can also be affordable. Today, our solutions reach 60+ countries, supporting 3,000+ industrial clients and millions of households worldwide. At Litree, water isn’t just our business—it’s our mission. We believe every drop matters, and we’ll keep pushing boundaries to create a future where clean, safe water is a universal right, not a privilege

    Ultrafiltration (UF) SystemsMembrane Filtration TechnologiespH Adjustment and Neutralization

    RCI Aquatech

    Verified

    India · 1-50 employees · 1 case study

    Founded in 2009, formerly known as Red Circle Industries (RCI), RCI Aquatech creates custom wastewater solutions based on end users’ requirements, which allow for optimally chosen components resulting in a solution that meets or exceeds customer needs. RCI Aquatech’s wastewater treatment systems combine necessary process technologies to reach required state and federal discharge limits and comply with local regulations. Our systems focus on removal of pollutants such as heavy metals, greases, suspended solids, oils, high salt content, toxic compounds, phosphates and more. Using chemical-physical treatment (coagulation, flocculation, and sedimentation), biological treatment (aerobic and anaerobic) and wet chemical oxidation (persistent or toxic organics). Our expertise comprises the following technologies:  Filtration & softening systems  Physicochemical treatment (coagulation-flocculation)  Membrane filtration (UF & RO)  Ion exchange  Chemical oxidation  Biological treatment  Zero liquid discharge (ZLD) system

    Activated Carbon FiltrationMicrofiltration (MF) SystemsReverse Osmosis (RO) Systems

    Related providers

    Listed for overlapping capabilities, not for oil & grease removal specifically.

    Freytech Inc.

    Verified

    United States · 51-200 employees · 1 case study

    Freytech Inc., headquartered in Miami, Florida (USA), is an environmental technology company specializing in innovative, science-based solutions for the remediation and optimization of air, water, soil, and industrial fluid systems. Since 1996, the company has developed sustainable technologies that improve operational efficiency while supporting decarbonization and environmental stewardship. Its flagship innovation, the Environmental Balance Device (EBD) Technology, is a patented and scientifically validated platform designed to enhance natural bioremediation and biotransformation processes in real time, without the use of electricity, chemicals, filters, membranes, or other consumables. EBD systems operate continuously for more than 15 years with minimal maintenance requirements. Scientific validation includes certification by the Ministry of Science and Innovation of Spain and confirmation as “Safe to Use” by Florida International University (USA). Freytech's technologies are deployed across municipal, industrial, agricultural, and energy sectors throughout Europe, North America, and the Middle East, supporting applications such as: Water and wastewater treatment optimization; Reduction of scaling, corrosion, biofouling, and sludge in pipelines and process equipment; Hard water conditioning and extension of reverse osmosis (RO) membrane life; Greenhouse gas, ammonia, and odor reduction; Soil, groundwater, river, and lake remediation; Agricultural irrigation improvement and soil restoration; Oil and gas infrastructure optimization, including paraffin, asphaltene, and fouling control. Freytech's solutions are designed to help organizations achieve operational excellence and sustainability goals simultaneously by reducing energy consumption, lowering maintenance costs, extending asset life, improving resource efficiency, and supporting ESG and net-zero strategies. EBD installations are highly scalable, can be completed in hours rather than months, and provide an affordable pathway for greenhouse gas mitigation at costs below USD 40 per tCO₂e. Mission: To deliver practical, sustainable, and economically viable technologies that restore environmental balance while enhancing industrial performance, resilience, and long-term competitiveness.

    Environmental Balance Device technologyMethan removalOffensive Odor Control
    C

    ChemTreat

    United States

    ChemTreat is one of the largest industrial water treatment companies in the United States, headquartered in Richmond, Virginia. It designs custom chemical treatment programs for boiler water, cooling water, pretreatment, wastewater and water reuse, combining field technical support, laboratory services and digital monitoring to improve efficiency and protect equipment across many industries.

    Boiler water treatmentCooling water treatmentPretreatment and filtration
    S

    Sorbster

    United States

    Sorbster specializes in industrial wastewater treatment, manufacturing adsorbent media to remove contaminants from water used in boilers, cooling towers, and other industrial applications. Its product range targets silica, selenium, mercury, copper, and multiple heavy metals, achieving removal rates up to 99 percent. Based in Cleveland, Ohio, the company supports customers with water diagnostics, pilot treatment programs, temporary treatment options, and pump-and-treat applications using standard industry tanks and cartridges.

    Water diagnostics and testingPilot treatment programsTemporary and emergency treatment options
    BP

    BI Pure Water

    Canada

    BI Pure Water designs and manufactures custom industrial and municipal water treatment plants, with over 30 years of experience serving municipalities, mining, oil and gas, pharmaceutical, and agricultural sectors. The company offers turnkey systems including mobile, trailer-based emergency potable water units deployed during disasters, as well as engineered modular fire pump plants. Based in Surrey, British Columbia, it delivers complete custom treatment solutions from design through manufacturing.

    Custom industrial water treatment plant design and manufacturingEmergency mobile potable water treatment systemsMunicipal wastewater treatment solutions
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    Buyer's guide

    The buyer's guide to oil & grease removal

    OverviewFAQScenarioQuestions to askCost driversRegulations

    Oil and Grease Removal from Water: DAF, API Separators, and Coalescing Plate Interceptors

    Oil and grease (O&G) in industrial wastewater includes free oil (droplets above 150 microns, easily settled or floated), dispersed oil (droplets 20 to 150 microns, requiring coalescing or flotation), emulsified oil (droplets below 20 microns stabilised by surfactants, requiring chemical emulsion-breaking), and dissolved hydrocarbons (require biological or activated carbon treatment).

    US EPA effluent guidelines specify O&G limits by industry: offshore oil and gas 29 mg per L (30-day average); petroleum refining 9.9 mg per L (30-day average, 40 CFR Part 419); and food processing varies by product. EU IED BAT-AEL for refineries: 1 to 5 mg per L O&G in treated effluent. Environment Agency UK trade effluent consent typical limit: 5 to 30 mg per L O&G.

    API (American Petroleum Institute) oil-water separators (API 421) use gravity separation for free oil removal: rectangular vessel with 30 to 60-minute HRT, horizontal flow velocity below 0.003 m per s (to prevent turbulence resuspending settled solids), surface loading 1.5 to 3.0 m3 per m2 per hour, oil collection by skimmer. API separators remove droplets above 150 microns at 90 percent efficiency.

    Coalescing plate interceptors (CPI, parallel plate or corrugated pack media) enhance API performance: plates at 45 degrees (chevron) with 15 to 50 mm spacing provide enhanced surface area for droplet coalescence and collection, removing droplets above 50 to 60 microns at 90 percent efficiency within a fraction of the footprint of an API separator. Dissolved Air Flotation (DAF) generates 20 to 80 micron bubbles (by dissolving air at 4 to 6 bar and releasing at atmospheric pressure) that attach to oil droplets and float them to the surface; removes droplets above 10 to 20 microns at greater than 95 percent efficiency.

    Chemical demulsification is required for stabilised oil-water emulsions (O/W emulsions from cooling lubricants, cutting oils, metal working fluids, food processing). Emulsion-breaking chemicals (cationic coagulants: polyDADMAC, Al/Fe salts; pH adjustment to ISO point of emulsifying agent; acid cracking of soap-type emulsifiers at pH 2 to 3) destabilise the emulsion and allow the oil phase to coalesce and separate.

    Acid cracking: adjust pH to 2 to 3 with H2SO4, heat to 50 to 70 degrees C, settle or DAF. Coagulation-based breaking: add 200 to 500 mg per L alum or ferric at pH 6 to 8, 2 to 5 minutes rapid mix, 15 to 20 minutes flocculation, then DAF removes floated oil-sludge complex. Ultrafiltration (UF) or microfiltration is an emerging replacement for chemical demulsification in cutting oil treatment, avoiding chemical waste.

    Post your oil & grease removal project

    Frequently asked questions

    What is the difference between an API separator and a DAF unit for oil removal?

    An API oil-water separator (API 421) uses gravity separation alone: oil rises to the surface (density difference) in a quiescent chamber, removed by skimmer; heavy solids settle to floor and are removed by scraper. Effective for free oil above 150 microns. Simple, low-cost, no chemicals needed. Limitations: large footprint (30 to 60 min HRT), ineffective for dispersed or emulsified oil below 150 microns. Dissolved Air Flotation (DAF) uses micro-bubbles (20 to 80 microns diameter, generated by air dissolution under pressure) that adhere to oil droplets and float them rapidly to the surface as a froth layer, removed by skimmer paddle. Effective for oil droplets above 10 to 20 microns. Chemical coagulant and flocculant addition (10 to 50 mg per L FeCl3 plus 1 to 5 mg per L polyelectrolyte) improves emulsified oil removal by breaking the emulsion before flotation. DAF achieves 95 to 99 percent O&G removal in a compact footprint (HRT 15 to 30 minutes). Capital cost: API separator $20,000 to $200,000; DAF $50,000 to $500,000.

    What are the discharge limits for oil and grease in industrial wastewater?

    US EPA effluent guidelines (sector-specific): oil and gas extraction (offshore): 29 mg per L monthly average total O&G (40 CFR Part 435); petroleum refining: 9.9 mg per L (30-day average), 15 mg per L (daily maximum) total O&G (40 CFR Part 419); food processing (meat, poultry): 10 mg per L (40 CFR Part 432); metal finishing: no explicit O&G limit but TSS and pH limits indirectly control emulsified oil. EU Industrial Emissions Directive (2010/75/EU) BAT-AEL for refineries: 1 to 5 mg per L O&G in treated effluent per BAT Conclusions published 2015. UK Environment Agency: site-specific consent limits typically 5 to 30 mg per L total O&G for discharge to sewer; 5 to 10 mg per L for direct discharge to surface water. Petroleum-contaminated stormwater from petrol station forecourts: EN 858-1 Class 1 separator required (effluent below 5 mg per L free oil).

    How is emulsified oil removed from wastewater?

    Emulsified oil (droplets below 20 microns stabilised by surfactants or mechanical emulsification) requires chemical or physical emulsion breaking before separation. Methods: (1) Acid cracking: reduce pH to 2 to 3 with H2SO4 (breaks soap-type emulsifiers by protonating carboxylate surfactants); heat to 60 to 80 degrees C to accelerate coalescence; settle or DAF to separate broken emulsion. Cost-effective for high-pH, soap-emulsified cutting fluid waste. (2) Coagulation: add alum (200 to 500 mg per L) or polyDADMAC (10 to 50 mg per L) to neutralise surface charge on oil droplets, allowing coagulation and DAF removal. Achieves O&G below 10 mg per L. (3) Ultrafiltration (UF, 0.01 to 0.1 micron): rejects oil droplets mechanically regardless of emulsion type; effective for waste cutting oils and coolants; permeate at below 10 mg per L O&G; generates concentrated reject (10 to 30 percent oil content) requiring further disposal. (4) Biological treatment: dissolved and emulsified hydrocarbons are biodegradable; activated sludge or biofilm systems after physical oil removal achieve effluent O&G below 5 mg per L.

    Can oil recovered from wastewater be reused?

    Oil recovery and reuse feasibility depends on oil purity and concentration. High-purity free oil skimmed from API separators at petroleum facilities: can be returned to the refinery crude oil feed or sold as slop oil at $150 to $400 per tonne (well below crude oil price due to water content and contamination). Edible oil recovered from food processing wastewater (DAF float): subject to food safety regulations, cannot be returned to food production; may be used as animal feed ingredient if clean, or as biodiesel feedstock. Mineral oil from metal working coolant waste: concentrated waste coolant (5 to 30 percent oil) from UF treatment can be burned as a fuel in cement kilns or co-fired industrial boilers under waste fuel permit conditions. Oil-water mixture skimmings from refinery API separators (3 to 10 percent oil): typically mixed with crude oil or burned as fuel. Recovery economics improve when oil commodity price is high; at oil prices below $50 per barrel, recovery from wastewater may be net-cost neutral versus disposal.

    Illustrative scenario · Automotive component manufacturer, West Midlands

    A composite drawn from typical projects in this category, not a single client engagement. Figures are indicative.

    Challenge
    A machining facility generating 180 m3 per day of mixed cutting fluid and rinse water with oil and grease concentrations ranging from 150 to 600 mg per L was discharging to sewer under a trade effluent consent specifying below 30 mg per L O&G. Consent exceedances were triggering consent review proceedings with the sewerage undertaker.
    Approach
    The existing gravity interceptor was replaced with a two-stage system: a coalescing plate interceptor removed free oil above 60 microns, followed by a DAF unit (with 20 mg per L ferric dosing and 2 mg per L polyelectrolyte) treating the plate interceptor overflow. A weekly oil skimmer servicing programme was implemented on both units. UF (0.05 micron PVDF) was added as polishing for the emulsified fraction from the grinding bays.
    Outcome
    Combined O&G in the DAF/UF effluent averaged 6.8 mg per L over the first 12 months of operation, well within the 30 mg per L consent limit. The sewerage undertaker formally withdrew the consent review. Recovered oil from the skimmers (3 to 4 tonnes per month) was collected by a licensed waste oil contractor and co-processed as secondary fuel.

    Questions to ask shortlisted providers

    5
    1. 01

      What is the oil and grease concentration, type (free, dispersed, emulsified), and flow rate of the wastewater stream?

      Technology selection depends entirely on droplet size distribution; misidentifying emulsified oil as free oil will result in a system that cannot meet the consent limit.

    2. 02

      What is the trade effluent consent O&G limit and how is it measured (total O&G, free oil, or n-hexane extract)?

      Measurement methodology matters; EN ISO 9377-2 (n-hexane extractable) and gravimetric methods give different results for the same sample, affecting compliance assessment.

    3. 03

      Are any surfactants, detergents, or emulsifying agents used in the process that could stabilise oil-water emulsions?

      Surfactant type and concentration determine what emulsion-breaking chemistry is required; some synthetic surfactants resist standard coagulation and require specific demulsification agents.

    4. 04

      What is the proposed oil skimmings disposal route and is there a licensed waste oil contractor with collection capacity?

      Recovered oil is classified as hazardous waste; disposal must be by a licensed contractor and tracked under waste duty of care; disposal cost affects the O&M budget.

    5. 05

      What are the ATEX zone classifications in areas where oil mist concentrations could reach flammable levels?

      Cutting oil mists can form flammable concentrations; DSEAR 2002 zone classification affects equipment specification for fans, motors, and control panels in the treatment enclosure.

    What drives cost in this category

    4
    Wastewater flow rate and O&G loading
    DAF unit capacity (and therefore capital cost) scales with flow; high O&G loads increase chemical consumption and skimmate volume, raising OPEX proportionally.
    Emulsification level and demulsification chemistry
    Highly stabilised emulsions requiring specialist coagulants (polyDADMAC, polymer blends) can increase chemical OPEX by 3 to 8 times compared with simple ferric-based DAF for free and dispersed oil.
    Polishing stage requirement
    UF or biological polishing adds 100,000 to 400,000 GBP capital for systems treating mixed free and emulsified oil streams; justified only where the consent limit is below 10 mg per L O&G.
    Recovered oil disposal contract and frequency
    Licensed waste oil collection costs 50 to 150 GBP per tonne; high-volume generators with oil quality suitable for re-refining may negotiate zero-cost or credit collection contracts.

    Key regulations and standards

    4
    WIA 1991 Section 118 Trade Effluent Consent
    Governs all industrial discharges to public sewer; O&G consent limits (typically 30 to 50 mg per L) are enforced by the sewerage undertaker, with consent review and surcharge for persistent exceedances.
    EN 858-1:2002 (Separator Systems for Light Liquids)
    European standard for the design, performance, and testing of oil separators; Class 1 separators (below 5 mg per L free oil in effluent) are required for petrol station forecourts and vehicle servicing areas.
    DSEAR 2002 (Dangerous Substances and Explosive Atmospheres Regulations)
    Requires ATEX zone classification where flammable oil mist or vapour may be present; affects equipment selection for fans, motors, and electrical installations in oil treatment enclosures.
    Hazardous Waste Regulations 2005 (England and Wales)
    Recovered oil and oily sludges are classified as hazardous waste (EWC 13 02); disposal must be by licensed carrier with Hazardous Waste Consignment Notes and registered waste site; retained for 3 years.

    From the Insider

    • Oil & Gas Produced Water Treatment: Options and Regulations
    • Dissolved Air Flotation (DAF): How It Works and Costs
    • Offshore Produced Water Treatment: The 30 mg/L Compliance Train
    • Sludge Dewatering: Methods, Equipment and Disposal Costs

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