Protocols Protocol: BMP Test

Biochemical Methane Potential (BMP) Test

Anaerobic batch fermentation assay for the evaluation of biogas and biomethane yield 

  • Biogas and Biomethane
  • Anaerobic Digestion
  • AMPTS® III

What does a BMP test measure?

Biochemical methane potential, also known as biomethane potential, describes how much methane an organic material can produce under defined anaerobic conditions. BMP testing is commonly used to characterise feedstocks, compare materials and assess their suitability for anaerobic digestion.

The result is usually reported as normalised methane volume per gram of volatile solids. It provides a consistent basis for comparing substrates, mixtures, pretreatments and additives under the same laboratory conditions.

How does a BMP test work?

A measured amount of substrate is mixed with an active inoculum and incubated in sealed reactors at a controlled temperature. Blank reactors containing only inoculum are tested in parallel, together with a positive control such as microcrystalline cellulose.

Methane production from the blank is subtracted from the methane measured in the substrate sample. The cumulative methane yield after the test reaches its termination criteria is then reported as the experimental BMP.

BMP results represent methane potential under controlled batch conditions. Actual production in a full scale digester will also depend on retention time, loading rate, process temperature and interactions between feedstocks.

Avoid common errors in BMP tests

Cassie Welander, PhD • 13 July, 2026

Mistakes in experimental design, inoculum selection, sample preparation, mixing and data analysis can affect BMP results. Read our article to learn how to avoid the most common problems.

Read the article

    What can BMP testing be used for?

    BMP tests can support several types of laboratory and operational decisions:

    • Compare methane yields from different feedstocks or suppliers
    • Assess variations between deliveries or production batches
    • Evaluate substrate mixtures and codigestion strategies
    • Compare untreated and pretreated materials
    • Study the effects of additives or potential inhibitors
    • Estimate the value of a feedstock based on methane potential
    • Screen materials before continuous digestion trials
    • Assess the anaerobic biodegradability of organic materials

    BMP testing and VDI 4630

    The german standard VDI 4630 is one of the most widely recognised protocols for biochemical methane potential testing. It provides guidance on substrate characterisation, sample preparation, experimental conditions, gas measurement and the validation of results.

    Under the protocol, BMP tests are normally performed at either 37 ± 2 °C or 55 ± 1 °C. An active digested sludge inoculum is used, with an inoculum to substrate ratio of at least 2:1 based on volatile solids. The experiment should also include an inoculum blank and a positive control, such as microcrystalline cellulose.

    Visit our VDI 4630 protocol page for further information about reactor sizes, sample preparation, controls and validation criteria.

    Explore VDI 4630 protocol

      AMPTS® III

      Automatic Methane Potential Test System (AMPTS®) III is the research-standard analytical tool preferred by scientists and engineers for conducting various anaerobic batch fermentation tests. AMPTS® is the only automated test apparatus referenced in VDI 4630 for biochemical methane potential (BMP), specific methanogenic activity (SMA) and residual gas potential (RGP).

      The system consists of 18 parallel reactors (9 reactor configuration available) and the same number of gas flow meters (flow cells) attached to a detection unit for online, automatic data acquisition. This allows for the real-time investigation of a high number of feedstock samples with high precision and accuracy.

      Explore AMPTS® III

      Recommended experimental conditions

      Experimental conditions

      Application notes for conducting BMP tests with AMPTS III

      Conditions

      Mixing (agitation system included with AMPTS III)

      Temperature

      Mesophillic (37°C) or thermophillic (55°C)

      Method & Equipment

      Gas volume measurement (CH4)

      Reactor Size

      0.5 – 2.0 L

      Sample

      Application notes for conducting BMP tests with AMPTS III

      Inoculum

      Digested sludge from municipal sewage waste or agricultural biogas installations.

      Amount of Inoculum

      400 – 1600 g (depending on reactor size)

      Substrate Form

      Powder or fragments < 10 mm

      Inoculum: Substrate ratio (ISR)

      2:1

      Blank & Controls

      Blank: inoculum only
      Positive control e.g. microcrystalline cellulose

      Validation criteria

      Application notes for conducting BMP tests with AMPTS III

      Replicates

      3

      Test Duration

      25-60 days, until a plateau (BMP0.5%)

      Other Criteria

      Positive control BMP should be within ±10% of the
      theoretical (e.g., cellulose: 671-820 biogas or 336-410
      CH₄/g VS).


      RSD of test material < 15% (homogeneous) or < 20%
      heterogeneous)

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