Drone view of EFI USA biogas facility with O2 injection system

Proprietary Technology

O₂ Injection & H₂S Removal

Reduce hydrogen sulfide from 8,000+ ppm to under 100 ppm. Eliminate monthly scrubber media costs.

90%

H2S Reduction

35K

$/Mo Savings (Avg)

Models Available

<100

ppm Output

O₂ injection treats the gas, not the water

EFI meters a small, controlled volume of air into the biogas headspace under a digester cover, typically 2 to 4 percent oxygen by volume. Sulfur-oxidizing bacteria living on the underside of the cover membrane use that oxygen to convert hydrogen sulfide into elemental sulfur. H₂S comes down from 3,000 ppm and higher to under 100 ppm, and often below 50, with no chemicals and no media to replace.

This is not lagoon aeration. Aeration pushes oxygen into the water column to turn an anaerobic lagoon aerobic, which stops methane production and gives up the biogas. Headspace O₂ injection leaves the liquid anaerobic, so the lagoon keeps producing gas while the sulfide comes out of it.

The cost difference against iron sponge and activated carbon is the reason most operators switch: $5,000 to $35,000 a month in media replacement versus $200 to $500 a month in electricity, with payback typically inside 6 to 12 months. Sizing detail is on the O2 injection system specifications page.

How It Works

Micro-Aeration Technology

EFI's proprietary O2 injection systems use micro-aeration to biologically convert hydrogen sulfide in the digester headspace. Controlled air injection promotes the growth of sulfur-oxidizing bacteria on the cover membrane surface, converting corrosive H2S into harmless elemental sulfur.

Air Injection

Controlled oxygen is injected into the cover headspace through a calibrated manifold system.

Bacterial Growth

Sulfur-oxidizing bacteria colonize the cover membrane underside in the oxygen-enriched zone.

H2S Conversion

Bacteria convert hydrogen sulfide into elemental sulfur, which deposits on the cover surface.

Clean Biogas

Treated biogas exits the system with H2S levels consistently below 100 ppm.

EFI biogas facility with O2 injection system

Product Line

14 Models for Every Scale

From small dairy operations to large industrial facilities, EFI offers a complete range of O2 injection systems sized to match your biogas flow and H2S concentration.

14 Models Available

Air capacities ranging from 40 scfh to 2,000+ scfh. Each system is custom-configured for your specific biogas flow rate and H2S concentration. Contact us for specifications and pricing.

Request Specifications

Economics

Eliminate Scrubber Media Costs

Traditional Scrubbers

$5,000-$35,000+ monthly media replacement
Frequent media changeouts and disposal
Inconsistent H2S removal as media depletes
Hazardous spent media handling and disposal
Operational labor for media management

EFI O2 Injection

$200-$500/month electricity cost only
No media replacement, ever
Consistent H2S removal performance
No hazardous waste generated
Minimal operational attention required

Applications

Where O2 Injection Works

Dairy Biogas

Reduce H2S in dairy digester biogas to protect engines, boilers, and RNG upgrading equipment from sulfur corrosion.

Swine Operations

Swine waste biogas often contains the highest H2S concentrations. O2 injection provides reliable treatment at any concentration level.

Food Processing

Food processing wastewater digesters produce biogas with variable H2S. O2 injection adapts automatically to changing conditions.

RNG Upgrading

Pre-treat biogas before RNG upgrading to protect sensitive membrane and PSA equipment from sulfur contamination.

FAQ

Frequently Asked Questions

No, and the difference matters. EFI's O2 injection treats the gas, not the water. Air is metered into the biogas headspace under the cover, where sulfur-oxidizing bacteria live on the underside of the membrane and convert H2S to elemental sulfur. The liquid stays anaerobic, so the lagoon keeps producing biogas. Lagoon aeration is the opposite approach: it drives air or oxygen into the water column to convert the lagoon from anaerobic to aerobic, which stops methane production entirely. Continuous aeration of a 2-acre lagoon draws 50 to 150 kW, roughly $30,000 to $100,000 a year in electricity, and gives up the biogas along with any carbon credit or energy revenue attached to it. EFI's headspace O2 injection runs $200 to $500 a month and leaves the biogas intact.

A covered lagoon producing biogas at around 2,000 ppm H2S typically needs 2 to 4 percent O2 by volume in the headspace for 90 percent or better removal. Dosing accuracy is what determines whether the system works. Too little oxygen and H2S drops partway but not far enough to protect flare burners and engines. Too much dilutes the methane, cuts biogas energy content, and pushes toward the lower explosive limit above 6 percent oxygen. EFI skids use proportional control that scales air delivery to biogas flow and H2S feedback rather than a fixed rate, and inject through multiple distribution points so oxygen spreads evenly under the cover instead of spiking in one spot.

Micro-aeration is the controlled injection of small amounts of oxygen into the biogas headspace under a digester cover. This promotes the growth of naturally occurring sulfur-oxidizing bacteria that convert hydrogen sulfide (H2S) into harmless elemental sulfur. The process is biological, continuous, and requires no chemical inputs or media replacement. EFI's proprietary O2 injection systems use this micro-aeration technology to eliminate H2S from biogas at a fraction of the cost of traditional chemical scrubbers.

EFI's O2 injection systems consistently reduce hydrogen sulfide from 3,000+ ppm to under 100 ppm, with many installations achieving levels below 50 ppm. The systems are designed to treat biogas with H2S concentrations ranging from a few hundred ppm to over 8,000 ppm. System sizing is based on biogas flow rate and incoming H2S concentration to ensure adequate treatment capacity for your specific operation.

O2 injection offers dramatically lower operating costs compared to chemical scrubbers. Traditional iron sponge or activated carbon scrubbers cost $5,000 to $35,000+ per month in media replacement alone, plus labor for changeouts and hazardous waste disposal. EFI's O2 injection systems cost only $200-500 per month in electricity with no media replacement ever needed. The biological process provides consistent H2S removal without the performance degradation that occurs as scrubber media depletes. Most installations achieve full payback within 6-12 months.

Yes, O2 injection is safe when properly designed and controlled. EFI's systems inject air at oxygen concentrations well below the lower explosive limit (LEL) for methane-oxygen mixtures. Built-in safety controls continuously monitor oxygen levels and automatically shut down the system if concentrations approach safety thresholds. EFI has safely operated these systems across hundreds of installations without incident.

O2 injection systems require minimal maintenance. Routine tasks include a quarterly blower check to verify proper air delivery, annual calibration of oxygen monitoring sensors, and periodic inspection of the injection manifold and piping. There is no media to replace, no chemicals to handle, and no hazardous waste generated. EFI offers O&M contracts that include all scheduled maintenance and 24/7 remote monitoring for complete operational oversight.

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Wastewater

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Ready to Eliminate H₂S?

Our assessment includes H₂S concentration analysis, system sizing, cost comparison vs. scrubbers, and projected ROI timeline.

Or call us directly: (307) 264-0309

Get O₂ System Assessment

O₂ injection treats the gas, not the water

Micro-Aeration Technology

Air Injection

Controlled oxygen is injected into the cover headspace through a calibrated manifold system.

Bacterial Growth

Sulfur-oxidizing bacteria colonize the cover membrane underside in the oxygen-enriched zone.

H2S Conversion

Bacteria convert hydrogen sulfide into elemental sulfur, which deposits on the cover surface.

Clean Biogas

Treated biogas exits the system with H2S levels consistently below 100 ppm.

14 Models for Every Scale

From small dairy operations to large industrial facilities, EFI offers a complete range of O2 injection systems sized to match your biogas flow and H2S concentration.