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Water: Petroleum

Effluent Guidelines: Petroleum Refining

petroleum refinery

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EPA promulgated the Petroleum Refining Effluent Guidelines and Standards (40 CFR Part 419) in 1974 and amended the regulations in 1975, 1977, 1982 and 1985.  The regulations cover wastewater discharges at over 140 refineries across the country.  The effluent guidelines and standards are incorporated into NPDES permits for direct dischargers, and permits or other control mechanisms for indirect dischargers (see Pretreatment Program).

What is Petroleum Refining?

Petroleum refineries process raw crude oil into three categories of products:

  • Fuel products – Gasoline, distillate fuel oil, jet fuels, residual fuel oil, liquefied petroleum gases, refinery fuel, coke, and kerosene;
  • Nonfuel products – Asphalt and road oil, lubricants, naphtha solvents, waxes, nonfuel coke, and miscellaneous products; and
  • Petrochemicals and petrochemical feedstocks – Naphtha, ethane, propate, butane, ethylene, propylene, butlyene, and BTEX compounds (benzene, toluene, ethylbenzene, and xylene).

Process Summary

Process Category
 Topping (Separating Crude Oil)
  •  Desalting
  • Atmospheric Distillation
  • Vacuum Distillation
Separates crude oil into hydrocarbon groups.
 Thermal and Catalytic Cracking
  • Thermal Operations
    • Delayed Coking
    • Fluid Coking/Flexicoking
    • Visbreaking
  • Catalytic Cracking
  • Catalytic Hydrocracking
Breaks large, heavy hydrocarbons from topping process into smaller hydrocarbons.
 Combining/Rearranging Hydrocarbons
  •  Alkylation
  • Polymerization
  • Catalytic Reforming
  • Isomerization
Processes hydrocarbons to form desired end products.
 Removing impurities
  •  Catalytic Hydrotreating
Removes impurities such as sulfur, nitrogen, and metals from products or waste gas streams.
 Specialty Products Blending and Manufacturing
  •  Lube oil
  • Asphalt
Blends product streams into final products or final processing into specialty products.

Major Wastewater Streams

Wastewater Description
 Desalter Water Water produced from washing the raw crude prior to topping operations.
 Sour Water Wastewater from steam stripping and fractionating operations that comes into contact with the crude being processed.
 Other Process Water Wastewater from product washing, catalyst regeneration, and dehydrogenation reactions.
 Spent Caustic Formed in extraction of acidic compounds from product streams.
 Tank Bottoms Bottom sediment and water settles to the bottom of tanks used to store raw crude. The bottoms are periodically removed.
 Cooling Tower Once-through cooling tower water and cooling tower blowdown to prevent buildup of dissolved solids in closed-loop cooling systems.
 Condensate Blowdown Blowdown from boilers and steam generators to control buildup of dissolved solid.
 Source Water Treatment System
Blowdown and Wastewater
 Source water must be treated prior to use in the refinery. Waste streams may include water from sludge dewatering if lime softening is used; ion exchange regeneration water; or reverse osmosis wastewater.
 Stormwater Process area and non-process area runoff from storm events.
 Ballast Water Ballast water from product tankers.


Petroleum refineries are categorized under North American Industry Classification System (NAICS) code 32411. (Note: the NAICS group listing is provided as a guide and does not define the coverage of the Petroleum Refining regulations. For precise definitions of coverage, see the applicability sections in 40 CFR Part 419.)

Facilities Covered

The Petroleum Refining effluent guidelines apply to facilities in five subcategories:

SubcategoryBasic Refinery Operations Included
 A. Topping  Topping, catalytic reforming, asphalt production, or lube oil manufacturing processes, but excluding any facility with cracking or thermal operations.
 B. Cracking Topping and cracking
 C. Petrochemical Topping, cracking and petrochemical operations*
 D. Lube Topping, cracking and lube oil manufacturing processes.
 E. Integrated Topping, cracking, lube oil manufacturing processes and petrochemical operations.*
* “Petrochemical operations” is the production of second generation petrochemicals (i.e. alcohols, ketones, cumene, styrene, etc.) or first generation petrochemicals and isomerization products (i.e. BTEX, olefins, cyclohexane, etc.) when 15 percent or more of refinery production is as first generation petrochemicals and isomerization products.

Covered wastestreams include process wastewater; ballast water; once-through cooling water; contaminated and uncontaminated stormwater.

Industry Studies

2015 Detailed Study

EPA is conducting a detailed study of the Petroleum Refining category to consider revisions to the regulations.

EPA specifically solicits data and information on the discharge of metals and dioxin from petroleum refineries, including for example, the source(s) of these contaminants, either in crude oil sources or in the refining process, the effects of new air pollution controls on wastewater discharges at refineries, and information on current and future trends in oil refining processes. The Agency also solicits data and information on current wastewater treatment technology performance at petroleum refineries, as well as any other information believed to be relevant to its study of this issue.

Previous Studies

  • 2004 Study (PDF) (127 pp, 707K) (Section 7 of the Technical Support Document for the 2004 Effluent Guidelines Program Plan; EPA 821-R-04-014, August 2004)
  • 1996 Study (PDF) (128 pp, 3.2MB) (EPA 821-R-97-003, April 1996)

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Implementation and Guidance Documents

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Rulemaking History

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Additional Information

For additional information regarding the existing Petroleum Refining Effluent Guidelines regulations, please contact Ahmar Siddiqui, siddiqui.ahmar@epa.gov or 202-566-1044.

For additional information regarding the 2015 Detailed Study, please contact Samantha Lewis, lewis.samantha@epa.gov or 202-566-1058.

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