Exhaust air purification in biogas plants – odors, gases, and emissions
oxytec systems for low-odor and emission-safe biogas production
Biogas plants make a valuable contribution to the energy transition – but they also cause complex emissions: ammonia, hydrogen sulfide, VOCs, methane, and intense odors occur in many places – in substrate acceptance, fermentation, drying, or desulfurization. These emissions pose a challenge for technology, approval, and local acceptance.
With UV ozone technology, aerosol separators, and optional activated carbon polishing, oxytec delivers proven systems for efficient odor and pollutant reduction – robust, scalable, and low-maintenance.
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Typical emission sources and pollutants in biogas plants
| emission source | Typical pollutants | Special features |
|---|---|---|
| Fermentation tanks (fermenters), fermentation residue storage | Methane (CH₄), ammonia (NH₃), hydrogen sulfide (H₂S), VOCs | Strong odor, explosive, harmful to the climate |
| Acceptance and storage of substrates | Odorous substances, bioaerosols, NH₃, VOCs | High odor pollution, emissions during handling and leaks |
| Desulfurization, gas purification | H₂S, organic sulfur compounds (mercaptans) | Corrosive, toxic, very odorous |
| Emergency flaring / safety venting | CO, NOₓ, CH₄ | Temporary high emissions, thermally induced |
| Peripheral technology (pumps, aggregates) | Oil vapors, VOCs | Small quantities, but continuous |
Why exhaust air purification is crucial in biogas plants
Odor reduction is crucial for acceptance in rural areas.
Methane and H₂S are considered relevant to climate and health.
TA Luft and GIRL stipulate limit values for VOCs and odors.
Sulfur-containing emissions cause corrosion and technical problems.
Emissions can result in licensing requirements and fines.
Legal requirements
- TA Luft 2021: VOC limits, H₂S and odor loads
- GIRL (Odor Emission Directive): Assessment of environmental pollution
- 4. BImSchV / BImSchG: Approval requirement for many biogas plants
- Support programs for low-emission technologies (e.g., manure bonus, climate fund)
oxytec provides support with odor reports, emission protocols, and technical documentation for approval authorities.
Get advice now – for low-odor, approval-compliant biogas production
Would you like to operate your biogas plant in a low-emission, technically reliable, and neighbor-friendly manner?
Contact us—oxytec will develop a customized exhaust air solution for substrates, fermenters, and more.
Oxytec solutions for biogas plants
UV ozone systems for breaking down odors and pollutants
Splits organic odor molecules, ammonia, H₂S, and VOCs
No open flame—no thermal post-combustion required
Ideal for fermentation-related odors and humid exhaust air
Aerosol separator for bioaerosols and dust
Removes droplets, solid particles, oil mist, and germs
Protects UV systems and ducts from contamination and deposits
Can be used with low pressure loss even at high volume flows
Activated carbon polishing for difficult emissions
Retention of persistent VOCs or mercaptans
Complements UV and aerosol technology in particularly sensitive applications
Increases approval reliability and reduces residual emissions
Typical areas of application
- Reception area and entry systems for organic substrates
- Fermenter and fermentation residue tanks with hood extraction
- Gas cleaning and desulfurization lines
- Storage halls, presses, and centrifuge areas
- Decentralized exhaust air sources such as pumping stations or pre-pits
Your advantages with Oxytec systems for biogas plants
- Effective odor reduction even under high loads
- Noticeably reduces NH₃, H₂S, VOCs, and bioaerosols
- No open flames, no additional energy consumption
- Low maintenance and robust in humid process air
- Adaptable to existing extraction and container systems
- Eligible for subsidies, compliant with regulations, future-proof
FAQ – Frequently Asked Questions
What emissions do biogas plants typically cause?
Depending on the process, the following substances may be produced:
- Ammonia (NH₃) from fermentation residue storage and substrates
- Hydrogen sulfide (H₂S) from fermentation processes and desulfurization
- Methane (CH₄) from leaks or venting
- Bioaerosols, VOCs, mercaptans with a strong odor
- These emissions are harmful to the climate, corrosive, and often subject to regulatory approval.
What technologies does Oxytec use for exhaust air purification?
Our systems combine:
- UV ozone reactors for the oxidation of VOCs, NH₃, and H₂S
- Aerosol separators for pre-cleaning humid or particle-laden exhaust air
- Activated carbon modules for fine cleaning of particularly critical odorous substances
- These components can be combined in a modular fashion and customized to suit individual requirements.
Are the systems suitable for humid, warm, and fluctuating exhaust air?
Yes – Oxytec systems have been specially developed for fermentation-related applications:
- Use in high humidity and temperatures up to 70°C
- Resistant to greasy, protein-rich, and microbial components
- Stable operation even with non-constant volume flow
How much does UV ozone reduce odors?
- Typically, odor load is reduced by 90% or more
- Noticeable effects also with mercaptans and ammonia
- Verification possible through olfactometric measurement (EN 13725) or VOC analysis
Can it be used in potentially explosive atmospheres?
Yes – we offer:
- Systems with ATEX-compliant equipment
- Consulting on zoning and integration
- Safe handling even with air containing CH₄ or H₂S
How maintenance-intensive are the Oxytec systems?
Maintenance requirements are very low:
- UV lamps: approx. 8,000–10,000 operating hours
- Pre-separator: cleaning every 1–3 months, depending on load
- Activated carbon (if installed): service life up to 12 months, depending on volume flow
- Optional: Remote monitoring and maintenance kits
How are the systems integrated into existing plants?
Our systems are:
- space-saving and modular (installation on fermenters, reception areas, technical rooms, etc.)
- connectable to existing pipelines or exhaust air ducts
- available as stationary or mobile units (container solutions)
Are there any funding opportunities for exhaust air purification in biogas plants?
Yes, for example through:
- Manure bonus / investment subsidies for emission-reducing measures
- Climate protection or air pollution control programs at federal and state level
- Promotion of combined measures with heat recovery
oxytec provides eligible technical documentation and advice on request.
Can the systems also be combined for heat recovery?
Yes – via:
- Heat exchanger after the cleaning unit
- Optional integration with hot water or air preheating
- Condoheat systems from Oxytec are compatible
