Impurities in the biogas process

When producing a biogas, various by-products are also created which disrupt the biogas process.
Impurities such as hydrogen sulphide (H2S) and ammonia (NH3) not only inhibit the production of methane, they can also have a serious effect on the acid-base equilibrium.
Which of the two substances is produced in higher quantities depends on the pH equilibrium.
The more acidic the medium, the more H2S is released; the more alkaline, the more NH3.

Since this data shows that the hydrogen sulphide has a much greater effect on the biogas process than the ammonia, the focus should primarily be on reducing H2S.

Hydrogen sulphide & Ammonia vs. pH value

By using Donau Bellamethan, you can reduce both impurities in the substrate: the hydrogen sulphide is bound using iron ions, and the ammonia content is reduced by a slight decrease in the pH value, making it acidic.
Hydrogen sulphide and ammonia then no longer feature in the gas phase.
Depending on the substrate, more or less sulphur is introduced into the fermenter, and the hydrogen sulphide concentration of the biogas changes accordingly.

The fluctuation margin and the average values of H2S and ammonia in the substrate are as follows in accordance with the 2006 German Association of Gas and Water study:


  Fluctuation margin Average value
Hydrogen sulphide 50 – 30.000 mg/m³ 500 mg/m³
Ammonia 0,01 – 2,5 mg/m³ 0,7 mg/m³


Since this data shows that the hydrogen sulphide has a much greater effect on the biogas process than the ammonia, the focus should primarily be on reducing H2S.

 
*http://www.schwefelwasserstoff.de/biogasanlagen


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