CSTR based Semi-Dry Fermentation Process

 Salient features of the technology

  • CSTR Semi-Dry Fermentation Technology: Designed for
    agro wastes like paddy straw, press mud, cane trash,
    Napier grass, poultry litter and more.
  • Over 100 Operational Plants in Europe: Demonstrating
    the technology's success and widespread use.

  • Developed by Dr. Friedmann: Co-founder of J & F Biogas,
    the technology originated in 2002-2003.

  • Space and Cost Efficiency: J&F's process-based digester
    reduces digester footprint and ground work costs.

  • Reduced Internal Power Requirement: Digesters
    consume only 50% of power compared to other

  • Repowering Opportunities: Existing plants can be
    improved through process optimization.


J & F biogas High load reactors

The loading rate of J & F biogas reactors are in the range of 8 to 14 kgs of ODM per m3 of reactor volume. Conventional reactors have a loading rate between 2 to 5 kg of ODM per m3. High loading rate is one of the main operating principles of J&F reactors. This process is particular suitable for substrates with 30-35 % DM content.

The main advantage of J & F process plant is a flexibility regarding the feedstock. If there are any changes in DM content of the feedstock’s from the initial design , for example sudden change of feedstock due to unavailability of planned feedstock’s will only have a less impact of operation of J & F process based digesters. The digesters and the robust components can adjust to the change of mix in feedstock’s.


Comparison of CSTR Semi-dry Fermentation Vs other technologies

ParametersCSTR semi Dry FermentationOther Technologies
Size of digester(M3) 3600 M3 700 to 10,000 M3
Operational Costs Due to lesser number of digesters/agotators and containerized feeding system the power required will be 50% of other technologies Number of agitators reuired will be   two times CSTR semi dry process and multiple pumps will be required for pumping slurry at various stages
water/slurry required for feed stocks
with 30% solids and 70% moisture
0 1:1 ratio

Dry matter %
(digestion capacity)

up to 35% 10-12%
co digestion with Multi feed stocks Greater flexibility with co-digestion with other feed stocks such as straw poultry litter etc Lesser flexibility for co-digestion with feed stocks with higher dry matter more water will be required for dilution
Liquied effluent /slurry generated post digestion Minimal liquid slurry generation due to higher viscosity inside the digester liquid slurry generation will be higher
Operation and maintenance Low(Agitator life time of 8+ years) Medium (Agitators will require regular maintenance)




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