⚡ BMP · SMA · Biogas Composition · Siloxanes · VDI 4630 · Water Sci. & Tech. 74.11 · 2016

Biochemical Methane Potential (BMP)

The critical parameter for biogas plant design — measured to international standards.

The Biochemical Methane Potential (BMP) determines the total methane yield of any organic substrate — the single most important design parameter for sizing an anaerobic digestion system, evaluating feedstock economics and optimising co-digestion blends. Biogroup follows the guidelines of "Towards a standardization of biomethane potential tests" (Water Science & Technology 74.11, 2016) — the internationally recognised consensus protocol for BMP testing.

From agro-industrial residues and municipal sludge to food waste and energy crops — Biogroup quantifies biogas and methane production, characterises the substrate and identifies the combinations that maximise methane yield and economic return.

BMP + SMA
Both key parameters
WST 74.11 · 2016
International consensus protocol
Co-digestion
Substrate blending optimisation
+35 years
Anaerobic treatment expertise
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Biogas plant design data
BMP is the primary input for sizing digesters, heat exchangers, gas storage and power generation units. No reliable engineering design can be produced without it — using literature values introduces uncertainty that compounds through the entire design.
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Feedstock economics & co-digestion
Compare methane yields across substrates and blends to identify the most economically attractive feedstock mix. Co-digestion optimisation can increase methane yield significantly above single-substrate operation.
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Full substrate characterisation
Beyond BMP — C:N ratio, VS/TS, pH, humidity, inhibitory compounds (ammonia, VFAs, sulphide) and biogas composition (CH₄, CO₂, H₂S, siloxanes) to fully understand feedstock behaviour in the digester.
What is the Biochemical Methane Potential test?
The standardised anaerobic batch test for methane yield determination
Protocol: Water Science & Technology 74.11, 2016 · "Towards a standardization of biomethane potential tests"

The BMP test is a batch anaerobic digestion experiment in which a substrate (the material being evaluated) is mixed with an inoculum (an active anaerobic sludge community) under controlled conditions of temperature and agitation. The cumulative methane produced over time is measured and reported as mL CH₄ per gram of volatile solids (VS) added — the BMP value.

🧫 Inoculum source
Active anaerobic sludge from a municipal or industrial WWTP digester. Quality and activity verified before testing.
⚖️ VS ratio (I:S)
Inoculum-to-substrate VS ratio controlled and reported. Critical to avoid substrate inhibition or inoculum limitation artefacts.
🌡️ Temperature control
Mesophilic (37°C) or thermophilic (55°C) — matching the operating temperature of the full-scale digester being designed.
📅 Test duration
Until the daily methane production rate falls below 1% of cumulative production — typically 30–60 days for most substrates.
Anaerobic digestion — the four-stage biochemical process
Understanding the microbiology underpins correct BMP test design and result interpretation
1
Hydrolysis
Complex polymers (proteins, lipids, carbohydrates) are broken down into monomers (amino acids, fatty acids, sugars) by extracellular enzymes.
Rate-limiting for complex substrates
2
Acidogenesis
Monomers are fermented to volatile fatty acids (VFAs — acetate, propionate, butyrate), alcohols, H₂ and CO₂ by acidogenic bacteria.
VFA accumulation = instability indicator
3
Acetogenesis
Longer VFAs are oxidised to acetate, H₂ and CO₂ by syntrophic acetogenic bacteria. Requires very low H₂ partial pressure — syntrophic with hydrogenotrophic methanogens.
H₂ interspecies transfer critical
4
Methanogenesis
Methanogenic archaea produce CH₄ from acetate (aceticlastic route, ~70%) and from H₂ + CO₂ (hydrogenotrophic route, ~30%). The final and most sensitive stage.
Most sensitive to inhibition
Specific objectives of the BMP test at Biogroup
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Quantify biogas production
Determine the cumulative biogas and methane yield (mL CH₄/g VS) for each substrate and substrate combination tested. Generate the methane production curve over time — the input for kinetic modelling and reactor sizing.
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Characterise the substrate
Full physicochemical characterisation including C:N ratio, pH, humidity, total solids (TS), volatile solids (VS), COD, TKN, ammonia nitrogen, alkalinity and conductivity — the parameters that govern anaerobic digestion performance.
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Identify optimal co-digestion blends
Test multiple substrate combinations to identify the blend that generates the greatest amount of methane — balancing C:N ratio, VS content and inhibitory compound concentrations for maximum yield and process stability.
Specific Methanogenic Activity (SMA) — the companion test
SMA — measuring inoculum activity and digester health
g COD-CH₄ · g VS⁻¹ · d⁻¹ — the maximum methane production rate per unit of biomass.
What SMA measures
The Specific Methanogenic Activity test determines the maximum methane production rate of an anaerobic sludge per unit of volatile solids — expressed as g COD-CH₄ · g VS⁻¹ · d⁻¹. It directly reflects the activity and health of the methanogenic archaeal community in the inoculum or in an operating digester.
Why SMA matters
A low or declining SMA is an early warning of digester instability — before VFA accumulation or pH drop become apparent. SMA testing is used to evaluate inoculum quality before BMP tests, to monitor operating digesters, and to assess recovery after toxic events or process upsets.
Inoculum quality verification
Confirm inoculum is active before BMP test — poor inocula give artefactually low BMP results.
Operating digester monitoring
Periodic SMA tracking detects population decline before operational failure occurs.
Toxicity & inhibition assessment
SMA at increasing substrate concentrations defines IC₅₀ — the inhibitory threshold for safe loading.
Substrate characterisation — parameters measured alongside BMP

BMP results alone are not sufficient for biogas plant design. Substrate characterisation provides the physicochemical context needed to understand why a substrate behaves the way it does in the digester — and to predict performance at full scale.

🧱 Solids content
Total Solids (TS) · Volatile Solids (VS) · Fixed Solids · Suspended Solids · Dissolved Solids
⚗️ Organic content
Total COD · Soluble COD · BOD₅ · BOD Ultimate · TOC · DOC · VFA (acetate, propionate, butyrate)
🌿 Nutrient balance
C:N ratio · TKN · ammonia nitrogen (NH₄-N) · Total phosphorus · Soluble phosphorus
🔬 Physical parameters
pH · conductivity · alkalinity (total and partial) · humidity · temperature · particle size distribution
☠️ Inhibitory compounds
Ammonia (free NH₃) · hydrogen sulphide · long-chain fatty acids (LCFAs) · heavy metals · antibiotics · disinfectants
⚡ Energy content
Theoretical methane yield from COD · lipid, protein and carbohydrate fraction · energy equivalents
Biogas composition analysis — beyond methane percentage
🔥 Biogas quality parameters
GC · electrochemical · IR analyser
Methane (CH₄): 50–75% typical in biogas. Primary energy carrier — higher % = higher calorific value.

Carbon dioxide (CO₂): 25–45%. Must be removed for biomethane upgrading and grid injection.

Hydrogen sulphide (H₂S): 100–2,000 ppm typical. Corrosive — critical for equipment protection and desulphurisation system sizing.

Hydrogen (H₂): Trace levels. Elevated H₂ indicates syntrophic imbalance and potential instability.
⚠️ Siloxanes in biogas — the overlooked problem
GC-MS · µg Si/m³ · D4 · D5 · D6 · L2 · L3
Siloxanes are silicone compounds (D4, D5, D6, L2, L3) found in consumer products that accumulate in municipal sludge and landfill biogas. When biogas is combusted in engines or turbines, siloxanes oxidise to silicon dioxide (SiO₂) — fine abrasive particles that deposit on engine pistons, valves and heat exchangers, causing severe wear and premature failure.

Siloxane analysis by GC-MS is essential before commissioning any cogeneration unit on municipal biogas.
Two fundamental objectives of anaerobic digestion
Anaerobic digestion achieves two objectives that reinforce each other
The degradation of organic materials such as agro-industrial residues through anaerobic digestion simultaneously addresses waste management and renewable energy production — both contributing to environmental preservation and operational sustainability.
Objective 1
♻️ Proper waste management
Stabilisation and volume reduction of organic residues. Reduction of pathogens and odour. Production of digestate — a nutrient-rich biofertiliser that displaces synthetic fertilisers. Compliance with increasingly strict organic waste disposal regulations.
Objective 2
⚡ Renewable energy production
Biogas is a renewable fuel suitable for heat, electricity (CHP), biomethane upgrading and grid injection. An additional source of income from waste. Carbon-neutral energy carrier that displaces fossil fuels and generates carbon credits under applicable schemes.
Substrates and feedstocks tested
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Agro-industrial residues
Grain stillage · vegetable oil press cake · fruit pulp · cassava bagasse
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Animal manure & slurry
Cattle · pig · poultry · dairy · feedlot wastewater
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Industrial wastewater
Food processing · brewery · dairy · starch · sugar
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Municipal sewage sludge
Primary sludge · WAS · thickened sludge · digested sludge
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Food waste & OFMSW
Source-separated organics · restaurant waste · canteen waste
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Energy crops & biomass
Maize silage · grass · sorghum · switchgrass · algae
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Landfill & leachate
Municipal landfill biogas · leachate · landfill organic fraction
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Novel & co-digestion blends
Multi-substrate combinations · biodegradable plastics · organic chemicals
Applications — when BMP testing is required
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New biogas plant design
BMP is the primary input for digester volume, HRT, OLR, gas storage and power generation unit sizing. No reliable engineering design can be produced from literature values alone — substrate-specific data is essential.
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Co-digestion optimisation
Testing multiple substrate combinations identifies the blend that maximises methane yield while maintaining process stability — balancing C:N ratio, VS content and inhibitory compound levels for maximum return.
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Feedstock evaluation & contracting
Compare methane potential of available residues before committing to feedstock contracts. BMP data provides the energy content basis for tipping-fee and gate-fee negotiations.
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Troubleshooting underperforming digesters
When an operating digester is not meeting expected gas production, combined BMP + SMA testing identifies whether the limitation is in the substrate, the inoculum activity or process conditions.
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Environmental assessment
BMP data supports environmental impact assessments, GHG emission inventories and carbon credit calculations for anaerobic treatment projects. Also used in anaerobic biodegradability testing under OECD 311 / ASTM D5210.
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R&D and product development
Screen biodegradable polymers, coatings and new organic materials for their anaerobic biodegradation potential. Complement aerobic biodegradability data for full lifecycle assessment.
Standards and reference protocols
Internationally recognised protocols applied at Biogroup
WST 74.11 · 2016
Consensus BMP Protocol
"Towards a standardization of biomethane potential tests" — the primary international consensus document for BMP test conditions, inoculum quality, I:S ratio and result reporting.
VDI 4630
German BMP Standard
Verein Deutscher Ingenieure standard for fermentation of organic materials — the most detailed technical standard for BMP test execution and reporting. Widely referenced in Europe and internationally.
OECD 311 · ASTM D5210
Anaerobic Biodegradability Standards
Applied when the objective is regulatory classification of biodegradability under anaerobic conditions — complementing BMP data with standardised pass/fail criteria for chemical registration and waste classification.
ISO 11734
Anaerobic Biodegradability in Digested Sludge
ISO method for evaluating the complete anaerobic biodegradability of organic compounds in digested sludge — used for chemical registration and hazardous waste classification.
Standard Methods APHA
Substrate Characterisation
Standard Methods for the Examination of Water and Wastewater (AWWA/APHA) applied for all substrate characterisation parameters — COD, BOD, TS, VS, TKN, ammonia, VFAs, alkalinity.
GC · GC-MS · HRGC
Biogas & Siloxane Analysis
Gas chromatography for CH₄, CO₂, H₂S, H₂ quantification. GC-MS for siloxane analysis (D4, D5, D6, L2, L3) — down to µg Si/m³ levels.
What Biogroup delivers
BMP result — mL CH₄/g VS added (and VS destroyed) with standard deviation
Methane production kinetic curve with modified Gompertz model fit
SMA result — g COD-CH₄ · g VS⁻¹ · d⁻¹ (when requested)
Biogas composition (CH₄, CO₂, H₂S, H₂) with GC analysis
Siloxane analysis (D4, D5, D6, L2, L3) by GC-MS — µg Si/m³
Full substrate characterisation: TS, VS, COD, BOD, C:N, TKN, NH₄-N, VFAs, pH, alkalinity
Theoretical methane yield calculation for comparison with experimental BMP
Lag phase, maximum daily methane rate and biodegradability index
Co-digestion results with ranking of blends by methane yield
Design recommendations for HRT, OLR and expected full-scale performance
Related services
BMP · SMA · Biogas Composition · Siloxanes · Co-digestion optimisation
Need BMP testing for your biogas project?
From a single substrate BMP to full co-digestion optimisation with biogas composition and siloxane analysis — Biogroup delivers the data you need to design, evaluate and operate your anaerobic digestion system with confidence.
Request BMP testing →
📞 +54 341 425-6431 📞 +54 341 447-4486 ✉ biogroup@biogroup.com.ar 📍 3 de febrero 920 · Rosario, Argentina Mon–Fri 08:00–17:00