You are the owner of a biogas plant and want to know the technical and economical consequences of using different mixtures of substrates and the effects on the process after changing the parameters used for running the plant.

The helpdesk can help you make a simulation of biogas production from co-digestate based on a concrete application and also give an evaluation on the economical consequences of these changes.

Consulting the biogas experts in your area of reference and after a brief discussion and evaluation of your activity, you will be advised about the management of AD Plants and about eventual improvements to your activity.

This information is proposed on the basis on the calculations and evaluations made with certain tools developed during the AGROBIOGAS Project and based on real activity results in various European regions.

The main information provided by the Helpdesk should help the farmer who:
  1. Needs to know the eventual biogas production (simulation toolkit) after modification of the substrates used
  2. Needs to know what are the amount of co-digestate should be produced using the local products (substrate database)
  3. Needs to know what type of equipment is needed for the development of a new plant and for improvement/modifications of existing plants when applying the substrates chosen for co-digestion (Investment Decision Tool)
  4. Needs to make a first financial outcome of a specific activity (Investment Decision Tool)
  5. Needs to know the suppliers of the various equipment needed (Investment Decision Tool)
  6. Needs to be advised on how to improve biogas' production and technical situations (Operating Guidelines)
  7. Needs to know how to to use the digestion residues as biofertilisers (Recommendations of AD sludge utilisation as bio-fertiliser)

Anaerobic Digestion Simulation Toolkit

This tool presents a vast list of substrates in order to run the model and evaluate the biogas production effectively. The Anaerobic Digestion Toolkit provides the link between agricultural substrates and the anaerobic digestion model. Additionally, the database provides the user with access to knowledge that has been gained through the Agrobiogas project.

These substrates are characterised and cover the main information such as:

  • Location and growing description
  • Physical characteristics: Yield data, Digestion information, Storage information and Handling information.
  • Chemical characteristics: Chemical composition, Trace elements and Methane Yield.
  • Biological characteristics: Moisture content, Lignin content, Cellulose and Hemicelluloses content etc...
  • Biogas potential

Up to 8 substrates can be selected, quantified (Kg of substrates in the biogas digester) and simultaneously chosen for running the evaluation.


Model substrate selection screen


The structure of your biogas plant (1 or 2 reactors) and other operational parameters will be also characterised and defined in order to create a simulation of the nearest conditions of your plant.


Model operational parameter selection screen


After running the simulation, the model proposes various outputs in order to evaluate the interest of using certain agricultural residues for biogas production.

The results of the model may be visualised graphically. Profiles, such as those shown in the Figures below are obtained and can be selected for each of the model variable outputs or additional states used by the model. Moreover, there is also the option to compare simulations of different substrates or compare the Outputs from two reactors if "2 Reactor configurations is selected". In this case the option of comparison of reactors is also available.


Example of different profiles obtained after model simulation



Other Example of Graphic results screens


This consultancy proposes to give you an evaluation of Biogas profiles and also an estimation of various other parameters. Each criteria can be given with variability during running time.
  • Engineering parameters
    • Total COD influent and effluent
    • Removal total COD efficiency
    • Volatile Solid influent/effluent
    • Removal VS efficiency
    • Total Solids
    • Alkalinity
    • Total Kjehldal Nitrogen (TKN)
    • pH
    • Organic loading rate (ORL)
    • Methane yield
    • Biogas yield


  • Biogas Characteristics
    • Normal Biogas production
    • Normal CH4 production
    • Normal CO2 production


  • Inhibition parameters (in order to verify that they will not have a negative effect in the whole system)
    • Limiting N inhibition (I N_lim)
    • Fatties inhibition (I h2_fa)
    • Valeric/butyric inhibition (I h2_c4)
    • Propionic inhibition (I_h2 pro)
    • Free ammonia inhibition (I nh3_xac)
    • Sulfurous acid inhibition (I h2s_xac)


  • Pressure parameters
    • Total Pressure (bar)
    • H2 pressure (bar)
    • CH4 pressure (bar)
    • CO2 pressure (bar)
    • Steam water pressure (bar)
    • H2S pressure (bar)


Examples of Graphic results screens



Profiles inside the reactor

Operational Guidelines

Experiences of many years - especially with low budget, small sized biogas plants - have shown that on the operator's side sometimes there is a great lack of information concerning the biogas plant. Therefore it is sometimes very difficult to find the reason for disturbance or inhibition of the process. The Guidelines make an overview of the essential data operator needed to benefit of a successful and efficient anaerobic digestion system.

1) The first part of the guideline describes the basics of successful plant operation, to enable operators to consider them already in the planning process and to avoid "beginner mistakes":
  • Considering the various processes according to the bacteria involved in the Digestion process using microbiological basics.
  • Describing the biogas processes through introduction to the most important technical terms and technical parameters.
  • Giving some indication regarding the favourable Living conditions for AD bacteria, the biochemical characteristics of substrates and the main information on Process control.
2) The core element of Operational Guidelines is the description, allocation to the process chain of AD and interpretation of the parameters. The processes mentioned in the simulation toolkit facilitate the interpretation of the figures calculated by the Simulation Toolkit but also other parameters.
Are presented parameters:
  • Total solids/ dry matter content (DM)
  • Organic dry matter content (oDM)
  • Digester volume
  • Retention time
  • Volatile removal
  • Temperature
  • PH-Value
  • Alkalinity
  • TKN (Total Nitrogen)/ Carbon - C/N - and CNPS ratios
  • Hydrogen partial pressure
  • Chemical Oxygen Demand (COD)
  • Gas production
  • Gas composition (CH4, CO2)
  • Methane to-COD ratio
Additional parameters:
  • FOS/ TIC value
  • VFA (=Volatile Fatty Acids)
  • Propionic acid and acetic acid
  • Ammonium and ammonia
  • Micronutrients (Trace elements)
  • Hydrogen sulfide (H2S) and oxygen (O2)
Every process parameter is described in four steps:
  • General description of the parameter
  • What does the parameter indicate?
  • Measurement
  • Remedy
3) Finally, some examples on trouble shooting, helpful hints on solutions.

Recommendations of Anaerobic Digestion Sludge Utilisation As Biofertiliser

The aim of the recommendations is to define quality criteria and indicators for the use of digestate as a bio-fertiliser by the farmers. In these guidelines you can find a review of the composition and the properties of AD sludge, a list of the advantages for using digestate and also some precautions to take during the storage and the application of AD sludge. The Guidelines are composed of three parts:

1) The benefits in using digestate
The process also permits the improvement of other parameters like olfactory disagreements, and the facilitating the problem of sludge dispersal due to low viscosity, and constitutes to a gain in money and is a good way to protect the environment due to the diminution of mineral fertiliser.
All the benefits and precautions are described in detail in the Recommendations Guidelines.

2) Recommendations for anaerobically digested sludge handling/application
The storage and handling of digestate requires some precautions. This fact is due to the increased value of volatile ammonia. The main recommendations are a cover tank, possibility of a double digester, rapid incorporation into the soil or injection in the soil. For the storage, it’s important to protect digestate from water, wind and to have a sufficient storage tank. The use (quantity, period, …) depends on the legal aspects of countries and from one land to another, but generally it follows the nitrate directive.
These recommendations will give you further details regarding these technical and legal aspects according to your location.

3) Quality label for AD sludge as bio-fertiliser
Member States don’t have the same opinion about the ‘high-added value’ that constitutes the digestate as a bio-fertiliser. For this reason it is important for Europe to develop a common Quality Certification System for digestate.
Those Guidelines provide some proposition of Quality label development that could be of interest to you for local or regional standardisation of sludge utilisation as biofertiliser.

It could be very advantageous to define a unique system for some essential sections:
  • Definitions in order to harmonise the vocabulary used, and list of “permitted matters” to compose the mix for the biomethanation with the protocols used for analyses.
  • Description of all the quality criteria with all the values that could be decided by the organism in charge of these decisions and presented as a model for the Member States.
  • Presentation of the elements needed for the management and operations of the plants, Information in terms of process (pre-treatment, treatment) but also in terms of workforce and finally some recommendations concerning building and application requirements.
  • Description of all the elements concerning the certification with explanation of the organisms and their responsibilities, the certification and control processes with recommendations in this field.