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Effluent Guidelines

Petroleum Refining Effluent Guidelines

Petroleum refinery photoEPA 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 dischargersHelpdirect dischargerA point source that discharges pollutants to waters of the United States, such as streams, lakes, or oceans., and permits or other control mechanisms for indirect dischargersHelpindirect dischargerA facility that discharges pollutants to a publicly owned treatment works (municipal sewage treatment plant). (see Pretreatment Program).
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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 & kerosene
  • Nonfuel products—asphalt and road oil, lubricants, naphtha solvents, waxes, nonfuel coke, & miscellaneous products
  • Petrochemicals and petrochemical feedstocks—naphtha, ethane, propane, butane, ethylene, propylene, butylene, and BTEX compounds (benzene, toluene, ethylbenzene & xylene)
Process Summary
Process category Processes Description
Topping (Separating crude oil)
  • Desalting
  • Atmospheric distillation
  • Vacuum distillation
Separates crude oil into hydrocarbon groups
Thermal & 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 & metals from products or waste gas streams
Specialty products blending & 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 & fractionating operations that comes into contact with the crude being processed.
Other process water Wastewater from product washing, catalyst regeneration & 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 & 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 solids.
Source water treatment system 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 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.)

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Facilities Covered

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

Petroleum Refining Subcategories
Subcategory Basic 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. Petro-chemical Topping, cracking & petrochemical operations*
D. Lube Topping, cracking & lube oil manufacturing processes
E. Integrated Topping, cracking, lube oil manufacturing processes & 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 & isomerization products.

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Industry Studies

In 2019 EPA concluded a study of wastewater discharges from petroleum refineries. As part of that study, EPA prepared a report compiling data on petroleum refining facilities, refinery wastewater characteristics, and available technologies for treating refinery wastewater.

Previous Studies

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Implementation and Guidance Documents

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Rulemaking History

1985 Amendment

Revised BAT, added stormwater limits (pursuant to litigation)
  • Documents, including:
    • Final rule (Correction; August 12, 1985)
    • Final rule (July 12, 1985)
    • Proposed rule (August 28, 1984)

1982 Amendment

Revised BAT, PSNS, PSES (pursuant to 1977 CWA amendments & litigation)
  • Documents, including:
    • Final rule (October 18, 1982)
    • Development Document (October 1982)
    • Proposed rule (December 21, 1979)

1977 Amendment

Established PSES
  • Documents, including:
    • Interim final rule (March 23, 1977)
    • Development Document Supplement for Pretreatment (March 1977)
    • Proposed rule (May 9, 1974)

1975 Amendment

Revised BPT: TSS and chromium-VI limits
  • Documents, including:
    • Final rule (May 20, 1975)
    • Proposed rule (October 17, 1974)

1974 Initial Rulemaking

Established BPT, BAT, NSPS, PSNS
  • Documents, including:
    • Final rule (May 9, 1974)
    • Development Document (April 1974)
    • Proposed rule (December 14, 1973)

Additional Information

For additional information, please contact Samantha Lewis ( or 202-566-1058.

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