How Can H2S be Removed from Biogas?

How Can H2S be Removed from Biogas?

Biogas is obtained with a blend of numerous microorganisms due to the degradation of organic matter under anaerobic circumstances. Biogas generates H2S-Hydrogen Sulfide, carbon monoxide, ammonia, and other minor products. The concentration of H2S varies in the feedstock but always present as a significant contaminant within biogas. It is corrosive and poisonous. It harms instrumentation, equipment, and piping. Boilers withstand 1000ppm H2S, while internal combustion engines withstand less than 100ppm H2S. This is why H2S removal from biogas is essential.

Common methods of H2S removal from biogas

These methods involve any one of the processes below:

  • Adsorption on a solid like iron oxide material or activated carbon
  • Adsorption on a liquid-like caustic or water solution
  • Biological conversion

The methods for the removal of H2S from biogas are:

Biological Desulphurization

Biogas Biological desulphurization is carried with microorganisms. The majority of micro-organisms that oxidize H2S are from the Thiobacillus family. Add some stoichiometric oxygen amounts for microbiological sulfide oxidation to the biogas. This method is for H2S concentration of up to 2 percent to 6 percent air within biogas.

Add in air or oxygen right into the storage tank or digester at the identical time as that as a gas holder. The microorganisms are ubiquitous and don’t need inoculation. They develop on the digestive surface that provides the required nutrients and microaerophilic surface. They form yellow sulfur clusters. Based on temperature, the amount, the reaction, and location of air placed in H2S could be minimized by 95 percent to below 50ppm.

Biogas Bus

Safety measures should be taken to permit air overdosing during pump failures. The air within biogas is explosive from 6 percent to 12 percent, based on content methane. There is a little danger of liquid/gas interface corrosion within steel digester with no protection from rust.

Iron chloride dosage

Iron chloride could be directly fed to feed substrate or to digester slurry in a pre-storage tank. Generated H2S reacts with Iron Chloride and particles of iron sulfide salt. This process is highly efficient in minimizing high levels of H2S.

It is, however, less effective in getting a stable and low level of H2S within a range of vehicle fuel needs. This is a partial H2S removal from the biogas method. This is done to prevent corrosion in the process equipment. This method has to follow up with the complete final removal of H2S up to 10 ppm.

The cost of investment in this H2S removal process is constrained. This is because the only investment required in this is a tank for storage of a solution of iron chloride along with a dosing pump. On the contrary, the cost of operation shall be high because of the iron chloride prime cost.


As biogas generates certain minor components that can be harmful to the equipment and piping, they must be eliminated. H2S is one such component that is poisonous and harmful. H2S removal from biogas can be done using biological desulphurization, biogas bus, and iron chloride dosing. These methods can eliminate H2S from biogas efficiently. This way the corrosion of the equipment and piping can be minimized. As H2S gas is also harmful to humans causing nausea, headache, skin, and eye irritation, it needs to be eliminated at all costs.

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