Biogas desulphurisation is an essential stage in renewable energy production. This process removes hydrogen sulphide (H₂S), a highly corrosive and toxic gas that compromises the safety, efficiency and profitability of biogas plants.
Thanks to technological advances, it is now possible to achieve more effective, sustainable and economical desulphurisation through the use of iron hydroxides, materials that have become the technical standard of reference in the sector.
At Nalon Minerals, we work to optimise the removal of H₂S in biogas with innovative solutions, such as our N -Bio medium, formulated with highly reactive iron hydroxides.
- Why is the desulphurisation of biogas key?
- Current methods of biogas desulphurisation
- Biogas desulphurisation with iron hydroxides: how it works
- Advantages of desulphurisation of biogas with hydroxides of iron
- Innovation at Nalon Minerals: the N-Bio medium
- Desulphurisation of biogas: efficiency and sustainability
- Iron hydroxides versus other methods of biogas desulphurisation
- Biogas desulphurisation with iron hydroxides, a safe bet
Why is the desulphurisation of biogas key?
During anaerobic digestion, organic matter generates biogas, composed mainly of methane (CH₄) and carbon dioxide (CO₂). However,
- Severe corrosion of engines, pipes, valves and systems of combustion.
- Safety risk due to toxicity and the generation of harmful compounds.
- Reduced service life of power generation equipment.
- Regulatory non-compliance, as H₂S must be reduced to levels below 250 ppm before upgrading to biomethane.
For all these reasons, the desulphurisation of biogas is not optional, but rather an essential step to ensure safe energy production that is clean, safe and efficient.
💡 More information about this process on our page of Biogas desulphurisation page.
Current methods of biogas desulphurisation
There are different technologies for removing H₂S from biogas. Each has advantages and limitations depending on operating conditions and gas purity objectives.
1. Oxygen or air injection
It consists of introducing oxygen (O₂) directly into the biogas or digester, oxidising the H₂S into elemental sulphur or sulphates.
Although it is a method with low initial cost, it presents ATEX risks, possible alterations in the biological activity of the digester and the need for continuous safety monitoring.
2. Impregnated activated carbon
Activated carbon retains H₂S by adsorption. It performs well at low and stable concentrations, but replacement costs are high, and its disposal generates hazardous waste.
3. Chemical or biological washers
In these systems, the gas passes through a liquid solution that absorbs the H₂S. Although effective, they involve high maintenance, constant consumption of chemicals, and higher CAPEX.
4. Iron hydroxides
Iron hydroxides react directly with H₂S to form iron sulphide (FeS), eliminating the contaminant in a stable manner without the need to add oxygen.
This method has gained prominence due to its efficiency, safety and operational simplicity, becoming the preferred solution in biogas plants of all sizes.
Biogas desulphurisation with iron hydroxides: how it works
The chemical principle behind iron hydroxides is simple and effective. When H₂S comes into contact with the medium, it reacts according to the following equation:
Fe(OH)₃ + 3H₂S → 2FeS + S + 3H₂O
The result is a conversion of hydrogen sulphide into iron sulphide, a stable solid that can be removed or, in certain cases, integrated into the digestate without altering the balance of the process.
This reaction occurs at ambient temperature, without additional energy consumption and without risk of combustion, which makes it a safe and sustainable alternative to other methods. a14> compared to other methods.
Advantages of desulphurisation of biogas with hydroxides of iron
High operational efficiency
Iron hydroxides maintain consistent performance even with variations in biogas load or flow rate, achieving H₂S levels below regulatory limits.
Guaranteed security
Unlike systems that introduce oxygen, desulphurisation with iron does not generate explosive atmospheres nor does interfere with the biology of the digester.
Easy integration
It can be applied by means of on-site dosing or in external beds, without the need to modify the existing infrastructure.
Predictable maintenance
Control is limited to monitoring H₂S output and planning replacement of the reactive medium.
Digestate recovery
The by-product generated (FeS) can be integrated into the digestate, increasing its agronomic value thanks to the addition of iron and sulphur, essential nutrients for soils.
🔗 Discover more about the potential of the hydroxides of iron in Desulphurisation of biogas.
Innovation at Nalon Minerals: the N-Bio medium
At Nalon Minerals we have developed N-Bio, an advanced medium of iron hydroxides and oxides optimised for H₂S capture in biogas. Designed for both direct dosing into the digester and external bed systems, N-Bio combines reactive efficiency, low pressure drop and extended service life.
Key features of N-Bio
- High capacity for adsorption of H₂S.
- Stable efficiency in the face of variations in flow or concentration.
- Simple maintenance and low OPEX.
- Possible partial regeneration by means of controlled aeration.
- Product solid, safe and easy to handle.
Furthermore, its application improves the stability of the anaerobic process, acting as a buffering effect against H₂S peaks and helping to maintain optimal conditions in the reactor.
💬 Would you like to find out how N-Bio can be adapted to your facility?
Contact our team and request a personalised study on desulphurisation with iron hydroxides.
Desulphurisation of biogas: efficiency and sustainability
One of the main challenges in biogas treatment is combining technical performance and environmental sustainability. Iron hydroxides meet both criteria:
- They do not generate liquid waste or hazardous emissions.
- Its by-product (FeS) is stable and can be recovered.
- They do not require additional energy for their reaction.
- They reduce the use of harsh chemicals.
As a result, its adoption in the sector is growing steadily, gradually replacing more expensive or high-risk technologies.
Iron hydroxides versus other methods of biogas desulphurisation
| Criterion | Iron hydroxides (N-Bio) | Oxygen injection | Activated carbon |
|---|---|---|---|
| H₂S efficiency | High and stable at different flow rates | Variable | Good, but sensitive to humidity. |
| Safety | ATEX risk-free | Risk of combustion | Safe |
| Operational complexity | Low | High | Medium |
| Operating cost (OPEX) | Low and predictable | Low reagent, high monitoring | High (frequent replacement) |
| Waste management | Stable, manageable FeS | Elemental sulphur or sulphates | Hazardous waste |
| Sustainability | High | Medium | Low |
Biogas desulphurisation with iron hydroxides, a safe bet
The desulphurisation of biogas using iron hydroxides has established itself as the most balanced option in terms of technical efficiency, operational safety and environmental sustainability.
At Nalon Minerals, we promote this technology through N-Bio, a high-performance medium designed to guarantee stable results, low costs and a positive impact on the circular economy.
If you are looking for a reliable solution for biogas desulphurisation, discover the advantages of working with Nalon Minerals. Visit our page on
Biogas desulphurisation or request information on the use of N-Bio tailored to your plant.
Frequently asked questions about biogas desulphurisation
¿Qué es la desulfuración de biogás y por qué es necesaria?
Biogas desulphurisation removes H₂S, a toxic and corrosive gas that damages equipment and reduces fuel quality. It is essential for producing high-purity biomethane and complying with environmental regulations.
¿Qué ventajas ofrece la desulfuración con hidróxidos de hierro frente a otros métodos?
Provides greater security, efficiency constant and low cost operating, without introducing oxygen or generating hazardous waste.
¿Qué mantenimiento requiere un sistema de desulfuración de biogás con hidróxidos de hierro?
It is only necessary to monitor the output of H₂S and replace the reactive medium in a planned manner . It is a predictable system with low maintenance.
¿Dónde puedo obtener asesoramiento técnico sobre desulfuración de biogás?
At Nalon Minerals, our specialists can help you size and optimise your system.
See our Biogas Desulphurisation page for more information.
