BMP testingAlgae and aquatic plants

Cyanobacteria (Phormidium, Desertifilum, Anabaena, Nostoc) — BMP: 4 studies, weighted mean 152 m³ CH₄/t VS

Cyanobacteria are photosynthetic microorganisms; the entry groups Phormidium, Desertifilum, Anabaena and Nostoc from several studies under different conditions.

CH₄ ≈ 58 % (estimate)

Published 29 April 2020Updated 29 October 20263 min readFeedstockData Editorial Team

Photo Christian Fischer / Wikimedia Commons, licence CC BY-SA 3.0, source file; changes: cropping

Weighted mean: 152m³ CH₄/t VS
Range: 28–308m³ CH₄/t VS
Records: 4studies
Publications: 2sources
Temperatures: —of the test

Methane in biogas

≈55–62% CH₄

Medium methane content · ≈ 5.8 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (protein-rich (process classification)) and the yields of compound groups according to FNR.

How we calculate it and what the zones mean

Rating for biogas plants

not rated — editorial rating for biogas plants

Not rated: no dry matter or volatile solids in the data. We calculate the rating when the dry matter and volatile solids of the material are known.

Editorial rating per the methodology

Add to the co-digestion calculator CSV data

BMP curves from 4 studies

Weighted mean Individual records

Dashed lines are a model curve (first-order kinetics, B(t) = B₀·(1 − e^−kt)); the end point comes from the publication. All curves are model curves.

Cumulative methane production over the test [m³ CH₄/t VS]. The thick line is the weighted mean of all records (152); dots mark the end values given in the publications. Point at the chart to read values; click a legend item to hide or show a record.

Records and sources

Download CSV

Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Fermoso et al. (2016) DOI	28	—	Nostoc sp.	end point (model curve)
Perendeci et al. (2019) · 1 DOI	229	—	Anabaena variabilis	end point (model curve)
Perendeci et al. (2019) · 2 DOI	293	—	Phormidium animale	end point (model curve)
Perendeci et al. (2019) · 3 DOI	308	—	Desertifilum tharense	end point (model curve)
Weighted mean	152	arithmetic mean 214, SD 129

Process properties

protein-rich
nitrogen-rich
dilutes the feed (low DM)
variable composition
editorial classification

Low confidence: the description is based on general characteristics of the substrate group, not on studies of this material. Treat it as a hint to be verified.

Advantages

Methane yield in the compendium: median 261 (range 28–308) m³ CH₄/t VS, 4 records from 2 papers (weighted mean 152).

Drawbacks and risks

The high protein content of the cells causes release of ammonia, which can be toxic to the process (Sialve et al. (2009); Rajagopal et al. (2013))

Co-digestion — what to combine it with, what to watch out for

combines well
substrates: carbon-rich — e.g. Wheat straw, Maize silage (whole crop), Cereal straw (unspecified), Willow (short rotation), Cardboard and paperboard
The low C/N of algal sludge was balanced by the addition of paper: 50-60% VS of paper increased the rate of methane production, optimum C/N 20-25.^[1][2]
caution
substrates: nitrogen-rich — e.g. Pig slurry, Poultry manure, Waste activated sludge (secondary sludge), Chlorella vulgaris, Nannochloropsis salina
Algal protein releases ammonia; additional nitrogen sources increase the risk of ammonia inhibition.^[2][3]

Dosing

No source limits on the dose for this substrate.

Introduce gradually, starting with a small dose and monitoring the process (e.g. FOS/TAC, pH, gas composition).

Practical requirements

Do not dry the biomass before feeding: drying lowered biogas production to about 80% (Mussgnug et al. (2010))
Monitor ammonia (high protein) and, for marine species, sodium (Sialve et al. (2009))

Sources of the process data

The co-digestion calculator will assess a specific mixture containing this substrate.

What it is and where it comes from

Cyanobacteria are prokaryotic organisms capable of photosynthesis. The dataset collects the genera Phormidium, Desertifilum, Anabaena and Nostoc, studied in several papers, one of which concerns isolates from Turkey. The biomass is obtained from cultivation in photobioreactors and ponds or from blooms in water bodies. Blooms are an environmental problem, and collecting them carries the risk of the presence of toxins produced by some strains.

Properties relevant to digestion

Cyanobacterial cells contain no lignin, but they have cell walls of peptidoglycan and mucilaginous sheaths, which can slow hydrolysis. The biomass contains a lot of protein, which in digestion leads to the formation of ammonia, and at a high load to its inhibitory effect. The C/N ratio is often low, so co-digestion with carbon-rich material works well. Some strains produce toxins, the presence of which requires separate assessment.

How to read the spread of results

The data comprise several records from different strains and several studies, without a stated temperature, because they were read from abstracts. The result depends on the species, cultivation conditions (light, medium, growth phase), the method of harvesting and dewatering, cell disruption and inoculum. Natural blooms differ in composition from monoculture cultivations, so transferring values from one source to another is risky.

In biogas plant practice

In Poland, cyanobacterial biomass is a research material or a waste from the cleaning of water bodies, not a regular stream. Should it be used, care must be taken over thickening (most of the mass is water), ammonia control, provision of a carbon co-substrate and testing for the presence of toxins. The seasonality and unpredictability of blooms make it difficult to plan supplies.

If practical use is planned, it makes sense to establish beforehand whether the biomass comes from controlled cultivation or from a natural bloom, because the risk of toxins and contaminants depends on it. Using cyanobacteria in co-digestion with slurry or carbon-rich material is usually safer than digesting the biomass alone, because it dilutes nitrogen and makes it easier to maintain a stable pH.

Methodology in brief

BMP is the amount of methane obtained from volatile solids (VS) in a batch test, given in m³ CH₄ per tonne of VS (numerically the same as NmL CH₄/g VS in the publications) and converted to normal conditions (0 °C, 101.325 kPa). The weighted mean gives each publication a total weight of 1, split equally between its results for the substrate — a paper testing twenty varieties does not outweigh a paper with a single sample. In inter-laboratory programmes the unit is the laboratory (total weight 1), and within it the weight of a test grows with the number of bottles (replicates). Results after pretreatment (e.g. thermal, chemical, enzymatic) are shown separately and are not included in the mean.

Solid lines are curves measured in the tests. Where a publication gives only the final result, we draw a first-order kinetic model, B(t) = B₀·(1 − e^−kt): only the end point comes from the publication, and the shape of the curve serves purely as visualisation — do not read the production on a particular day from it. For this substrate k = 0.102 d⁻¹ was assumed (median of rate constants k reported in the sources and/or fitted to the mean measured curves).

The statistics describe the spread of published results — a descriptive compilation, not a meta-analysis or a guarantee of plant yield.

Full methodology and correction policy

Bibliography

All sources of the site: bibliography.