US EPA Effluent Limitation Guidelines for oil & gas — the technology-based oil-and-grease limits for offshore and coastal produced-water discharge.
A related produced-water discharge standards topic.
A related produced-water discharge standards topic.
A related produced-water discharge standards topic.
Back to the overview this topic expands.
Produced-Water Discharge Standards — in depth
In US waters, EPA Effluent Limitation Guidelines set technology-based limits for produced-water discharge. Offshore guidelines cap oil and grease on a daily-maximum and monthly-average basis, measured per EPA Method 1664, with zero-discharge expectations onshore — shaping the deoiling and reinjection strategy.
What matters in practice
Daily-max and monthly-average caps.
Gravimetric oil-and-grease method.
Reinjection or haul-off onshore.
Permitted within ELG limits.
| Parameter | Daily max | Monthly avg |
|---|---|---|
| Oil & grease | 42 mg/L | 29 mg/L |
| Method | 1664 | 1664 |
| Onshore | Zero discharge | Reinject |
| Permit | NPDES | Required |
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Read MoreReynolds & Bauhm designs and delivers produced-water discharge standards solutions backed by process engineering and performance guarantees.
Fundamentals, design drivers and practical guidance
US EPA Effluent Limitation Guidelines for oil & gas — the technology-based oil-and-grease limits for offshore and coastal produced-water discharge.
Reynolds & Bauhm designs produced-water trains stage by stage against the governing discharge or reinjection spec — selecting separators, hydrocyclones, flotation and polishing media, and the demulsification chemistry that makes the physical stages perform.
Produced water is the largest waste stream in oil and gas, and its treatment is a staged de-oiling problem: free oil, dispersed oil and emulsified oil are removed in sequence because no single device handles all three economically. The target — whether for overboard discharge, reinjection or reuse — is set by regulation such as the OSPAR 30 mg/l dispersed-oil limit offshore or the US EPA effluent limitation guidelines.
The treatment train follows droplet size. Bulk gravity and plate separators (API/CPI) take out free oil and coarse droplets; hydrocyclones use centrifugal force to remove finer dispersed oil compactly, ideal for the weight and footprint constraints offshore; induced or dissolved gas flotation attaches micro-bubbles to smaller droplets to float them out; and polishing media such as walnut-shell filters or adsorption capture the residual to meet tight discharge limits.
What our engineers assess on every scope of this type
| Parameter | Typical basis | Why it matters |
|---|---|---|
| Dispersed oil | Hydrocyclones | Compact, high-G separation |
| Fine droplets | Gas flotation (IGF/DGF) | Floats out small droplets |
| Residual | Walnut-shell / adsorption | Polishes to discharge limit |
| Emulsions | Demulsifier / heat / electro | Breaks stabilised oil |
| Limit | OSPAR 30 mg/l / EPA ELG | Sets the train target |
| Free oil | API/CPI separators | Removes coarse droplets first |
Common questions on produced-water treatment
Stabilised oil-in-water emulsions resist gravity separation and must be broken first — with demulsifier chemistry, pH adjustment, or thermal/electrostatic treatment — so the downstream physical stages can then remove the freed oil.
It depends on the route: offshore discharge typically targets the OSPAR 30 mg/l dispersed-oil standard, US operations follow EPA effluent limitation guidelines, and reinjection is governed instead by solids and particle-size limits to protect the formation.
Reinjection shifts the priority from oil concentration to suspended-solids and particle-size control, because plugging solids damage formation permeability. US EPA Effluent Limit Guidelines is then tuned around filtration and solids removal rather than de-oiling alone.
Because free, dispersed and emulsified oil behave differently and no single device removes all three economically. US EPA Effluent Limit Guidelines sits within a sequence sized by droplet size, from bulk separation through to fine polishing.
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