Project Specification Guide
O2 Injection & H2S Removal Specifications
EFI USA engineers, sizes, supplies and installs oxygen and air injection systems for biological H2S reduction in covered lagoons and digesters. Use this guide to assemble the design inputs, define equipment interfaces and agree on the records needed for acceptance.
The project design establishes the equipment duties and operating limits. This page is a scope and information checklist, not an operating procedure.
What to send for an engineering review
Send the available readings and drawings with their dates and units. Mark estimates and missing information so the engineering review can distinguish measured conditions from assumptions.
| Input | Information to provide | Why it matters |
|---|---|---|
| Biogas flow | Normal, maximum and minimum flow; measurement location; units; temperature and pressure reference; wet or dry basis. | Separates the gas being treated from the air or oxygen supplied. Label SCFM and SCFH explicitly and identify the instrument basis. |
| Inlet gas quality | H2S readings with dates, sample points and analyzer range; methane and oxygen data where available; known startup or feedstock changes. | Defines the measured sulfur load and its variation. A single concentration without gas flow cannot establish equipment capacity. |
| Required outlet | The engine, flare or upgrader specification; applicable permit conditions; pipeline or offtake requirements where relevant. | Sets the acceptance criteria and identifies remaining polishing. There is no single outlet H2S target for every end use. |
| Covered system | Cover and basin drawings, operating levels, gas collection arrangement, mixers, existing injection equipment and access constraints. | Allows the distribution and installation scope to be reviewed against the existing structure and operating process. |
| Utilities and interfaces | Available electrical service, equipment location, ambient conditions, existing controls and the responsible site contacts. | Defines utility, installation and controls interfaces before equipment is selected. |
| Existing treatment | Scrubber and media details, recent inlet/outlet readings, changeout history, condensate handling and downstream equipment. | Makes the evaluation cover the entire treatment train, including equipment that must remain in service. |
On a small screen, scroll the table to read all columns. Send your project details through the EFI quote form.
Keep the flow and concentration measurements separate
Specify what each number measures. Oxygen-generator output, injected air and residual oxygen in biogas describe different parts of the system.
| Measurement | Meaning | Review point |
|---|---|---|
| Biogas flow | The gas stream being treated. | State the flow unit and reference conditions. Do not substitute generator capacity for biogas flow. |
| Injection air flow | The total air delivered by an air-injection supply. | Air includes nitrogen as well as oxygen. Review downstream gas-quality and inerts requirements. |
| Oxygen supply | Generator product flow together with its specified oxygen purity. | A concentrated-oxygen stream is not necessarily pure oxygen. Record flow and purity separately. |
| Residual oxygen | Oxygen concentration measured in biogas at a defined sample point. | This is an operating measurement, not the oxygen-supply flow or a universal dosing percentage. |
| Inlet and outlet H2S | Concentration measured before and after a defined treatment stage. | Pair readings with operating conditions and gas flow when assessing treatment performance. |
Select the oxygen source with the downstream process in view
Ambient air
Air injection introduces nitrogen along with oxygen. Review the resulting gas composition against the flare, engine or upgrader requirements before choosing the supply equipment. Air-flow capacity and oxygen delivery are separate specifications.
Concentrated oxygen
Specify the generator product flow and purity together with feed-air, electrical and installation requirements. Concentrated oxygen can reduce nitrogen addition compared with air, but the downstream process still determines acceptable oxygen and inerts levels.
Biological treatment reduces H2S loading. It does not remove every contaminant or establish pipeline-quality gas. Define remaining polishing, moisture removal and other cleanup against the actual end-use specification. EPA discusses these treatment stages in AgSTAR Operator Guidebook, section 7.9.
Agree on startup, acceptance and operator handoff
Use the proposal to assign these deliverables. Confirm the acceptance conditions and responsible parties before installation, including any work performed by equipment vendors or the site operator.
| Review area | Record or deliverable | Responsibility to agree |
|---|---|---|
| Design and scope | Approved drawings, equipment duties, materials, control narrative and interfaces. | Identify EFI, equipment-vendor, electrical/controls contractor and owner responsibilities in the proposal. |
| Installation checks | Inspection and leak-test records required by the approved design and equipment instructions. | Agree on the inspection and acceptance process before startup. |
| Instrumentation | Analyzer identification, calibration records, sample locations and flow-meter basis. | Confirm who verifies instruments and retains the baseline readings. |
| Controls and protection | Documented checks of the specified alarms, permissives, shutdowns and backflow protection. | Use project-specific approved settings and test procedures. This guide supplies no operating setpoints. |
| Performance acceptance | Gas-flow and gas-quality records for an agreed operating period and conditions. | Define sample points, outlet requirements, startup conditions and treatment-stage boundaries in advance. |
| Operator handoff | Operating procedures, maintenance schedules, manuals, training records and service contacts. | Confirm which startup, training and ongoing service tasks are included in the contracted scope. |
EPA's guide addresses monitoring, testing and site-specific operating manuals in sections 4 and 5, and biogas-system startup leak testing in section 7.2. Follow the approved project procedures and equipment instructions for the actual work.
Questions about the specification
How is an oxygen injection system sized?
What is the difference between air injection and concentrated oxygen?
What H2S level should the system achieve?
Can this guide supply operating or shutdown settings?
Technical references
EPA AgSTAR Operator Guidebook (November 2020): process monitoring, gas treatment, startup checks and maintenance. Its site-specific operating-manual guidance applies to the checklist above.
Muller et al., micro-aeration and oxygenation review (2022): research on biological H2S reduction and control strategies. The study supports the process context, not an EFI performance guarantee.
Page reviewed September 23, 2026.
Define Your Oxygen Injection Scope
Send gas data, site drawings and downstream requirements. EFI can review the equipment and installation scope with you.
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