Click to expand

Methane fermentation process parameters

Physico-chemical testing of feedstock entering a fermenter includes determining:

  • pH
  • electrical conductivity
  • dry matter content
  • organic dry matter
  • FOS, TAC and FOS/TAC ratio values
  • Kjeldahl nitrogen
  • ammoniacal nitrogen
  • profile of volatile fatty acids
  • micro and macro elements

Analysis of individual parameters provides information on the current state of the fermentation process. The pH value has a considerable influence on the activity of the microorganisms carrying out the methane fermentation process. The FOS value refers to the sum of all volatile organic acids present in the sample, while the TAC value determines the alkaline buffering capacity. In addition, the TAC parameter influences the stability of the pH. The FOS/TAC ratio determines the size of the methane fermentation load. The FOS/TAC ratio is one of the most important parameters to be systematically determined in any biogas plant, as it allows for the rapid detection of any adverse changes in the fermentation process.

Examination of the profile and concentration of individual volatile fatty acids by chromatography is a more precise analysis than the FOS analysis. From the results obtained, the ratio of individual volatile fatty acids (VFAs) can be calculated, which will indicate the correct fermentation process.

Disturbances in the indicated parameters lead to inhibition of bacterial growth and the amount of methane produced.

The standard analyses are supplemented by determining macro- and micronutrients such as P, K, Ca, Mg, Se, Co, Mo, Mn, Fe, Na, Cd, Cu, Cr, Ni, Pb, Zn, and Hg.

We offer testing packages with different scopes, including pH, conductivity, FOS values, TAC, FOS/TAC ratio, dry matter, organic dry matter content and ammoniacal nitrogen.

The results of digestion feedstock analyses, together with their proper interpretation, provide the necessary knowledge of the regularity of biochemical changes in the methanogenesis process.

It is possible to swap the scope of the proposed study packages according to the client’s individual needs.

As a supplement to the analyses carried out as part of biotechnology monitoring of biogas plants, selected or all macro- and microelements are determined. In most cases, we recommend that the first determination be carried out in its entirety, while the second should focus on the eight most important elements, which are crucial for the proper course of the methane fermentation process.

Digestion mass analysis packages
Parameter S M L XL
Dry matter
Organic dry matter  
Ammoniacal nitrogen  
VFA profile    

* Co, Se, Mo, Ni, Fe, Zn, Cu, Mn – A package of the most important micronutrients affecting the methanogenesis process, supplementation of which can be carried out if deficiencies are identified.


Interested in this service?
Contact us