Biological gas purification is the process of purifying the biogas without chemical additives. Therefore, it represents an interesting option compared to chemical alternatives with high operating costs. 

Biogas and landfill gas always contain a proportion of hydrogen sulphide (H2S). Said portion of H2S is usually in the range of 1,000 to  8,000ppm, but can also reach 2% by volume or more. 99% of this H2S must be removed from the gas, either for environmental reasons or due to the risk of corrosion for downstream assemblies.

The biological  desulphurization process is a cost-effective yet highly efficient solution. This is a biological process that requires no chemicals and virtually no consumables. If a limited amount of air (approx.  10 -15 % air) is added in relation to the gas flow rate, special bacteria (e.g. Thiobacillus and Solfolobus) convert the H2S into elemental sulphur and sulphuric acid.