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BMP testingWood and woody biomasssingle study (2 samples)

Albizia wood chips and leaves — BMP: 2 studies, weighted mean 137 m³ CH₄/t VS

Albizia is a fast-growing leguminous tree; the dataset contains wood chips and leaves from a single study, so the results reflect the difference between wood and green material.

rating: neutralCH₄ ≈ 54 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Dinesh Valke from Thane, India / Wikimedia Commons, licence CC BY-SA 2.0, source file; changes: cropping

Weighted mean
137m³ CH₄/t VS
Range
113–161m³ CH₄/t VS
Records
2single study (2 samples)
Publications
1source
Temperatures
37 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.4 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (protein from total nitrogen (N 3 % DM × 6.25)) and the yields of compound groups according to FNR.

How we calculate it and what the zones mean

Rating for biogas plants

neutral — editorial rating for biogas plantsNo clear advantages — worth charging a fee for accepting it

Potential per tonne of fresh matter: moderate, but limited by the poor degradability of the organic matter (61 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer, slow degradation.

Why? Rating factors

Potential per tonne +1

  • +1potential 61 m³ CH₄/t fresh matter (BMP 137 × DM 46.4 % × VS 96 %); low degradability of VS (BMP 137 m³ CH₄/t VS) — points capped

Process stability 0

  • 0no factors

Handling and costs −1

  • −0.5fibres, floating layer — shredding and intensive mixing
  • −0.5slow degradation — long retention time

Total points: 0 · thresholds: ≥ 2.5 very good, ≥ 1 good, below — neutral; negative with cumulative process risk.

Editorial rating per the methodology · confidence of the rating: low · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 2 studies

Weighted mean Individual records

BMP curves: Albizia wood chips and leavesCumulative methane production over time for 2 records and the weighted mean of 137 m³ CH₄/t VS. 2 of the curves are model curves (first-order kinetics).0501001502000510152025303540time [d]m³ CH₄/t VSGe et al. (2014) · 1: 113 m³ CH₄/t VS (model curve)Ge et al. (2014) · 2: 161 m³ CH₄/t VS (model curve)mean137

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 (137); 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
SourceBMP
m³ CH₄/t VS		TemperatureSampleCurve
Ge et al. (2014) · 1 DOI11337 °C · mesophilicalbizia chipsend point (model curve)
Ge et al. (2014) · 2 DOI16137 °C · mesophilicalbizia Leavesend point (model curve)
Weighted mean137arithmetic mean 137, SD 34

Typical composition

Dry matter (DM)
46.4% (range 36.5–56.2)
Volatile solids (VS)
96 % DM (range 93.7–98.3)
Nitrogen
3 % DM
C/N ratio
29.9

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 2 determinations, volatile solids: 2 determinations. C/N was calculated as the ratio of C and N content (% DM) from the same source.

Sources: Ge et al. (2014).

The composition of the raw material varies between batches — for plant calculations use an analysis of your own sample. The calculator inserts typical values automatically.

Process properties

  • fibrous
  • slowly degrading
  • carbon-rich
  • seasonal
  • 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 potential in the database: weighted mean 137 m³ CH₄/t VS (median 137; range 113-161; 2 records from 1 source).

Drawbacks and risks

  • Wood chips are a material with a high lignin content, hard for bacteria to access: low conversion and a long retention time (review by Hendriks 2009).
  • Spread of results in the database: standard deviation 34 at a mean of 137 m³ CH₄/t VS (2 records from 1 source).

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

Dosing

No co-digestion dose data; treat the material as a lignocellulosic additive after shredding, with its own BMP test. Literature values are indicative only.

Practical requirements

  • Shred: shredding increases the surface available for degradation and speeds it up, but does not necessarily raise the final gas yield (FNR 2010, Ch. 3 “Triturado”).
  • Control floating crust and sediment: when solids are fed directly into the digester, the risk of their formation depends on the substrate (FNR 2010, Ch. 3).

Sources of the process data

  1. Hendriks, A.T.W.M.; Zeeman, G. (2009) Pretreatments to enhance the digestibility of lignocellulosic biomass. Bioresource Technology
  2. Weiland, P. (2010) Biogas production: current state and perspectives. Applied Microbiology and Biotechnology
  3. Chen, Y.; Cheng, J.J.; Creamer, K.S. (2008) Inhibition of anaerobic digestion process: A review. Bioresource Technology
  4. Dahunsi, S. (2019) Mechanical pretreatment of lignocelluloses for enhanced biogas production: Methane yield prediction from biomass structural components. Bioresource Technology 280, 18–26
  5. Ge, X.; Matsumoto, T.; Keith, L.; Li, Y. (2014) Biogas energy production from tropical biomass wastes by anaerobic digestion. Bioresource Technology 169, 38–44
  6. FNR (2010). Guía sobre el Biogás – Desde la producción hasta el uso (hiszp. wydanie „Leitfaden Biogas”, GIZ 2013)

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

What it is and where it comes from

Albizia is a genus of trees in the legume family (Fabaceae), growing mainly in the tropical and subtropical zones. These species grow quickly, fix atmospheric nitrogen through symbiosis with bacteria and are sometimes considered as a source of energy biomass. The dataset contains two materials, described in a single study: wood chips and leaves. These trees are not cultivated in Polish conditions, so the entry is of informational value only.

Properties relevant to digestion

Wood chips are a lignocellulosic material: cellulose and hemicellulose are shielded by lignin, which anaerobic bacteria practically do not degrade. This results in a low degree of conversion and a long degradation time. Leaves contain less lignin and more protein and soluble sugars, so they degrade more easily, while contributing more nitrogen. Because legumes are rich in nitrogen, green material can improve the C/N ratio in mixtures with wastes poor in this element, but in excess it increases the risk of ammonia.

How to read the spread of results

The records describe different parts of the plant, so the difference between them is an expected phenomenon, not a measurement error. Both values come from a single study and a single set of conditions (mesophilic temperature, a specific inoculum), so variability between laboratories cannot be assessed. The result is also affected by the species, the age of the tree, the time of leaf harvest, the degree of chip comminution and the length of the test, because woody material degrades slowly and may not reach a plateau.

In biogas plant practice

Wood chips are not a substrate routinely sent for digestion in Europe: slow degradation, the risk of a scum layer and agitator wear argue for other uses of wood. If woody biomass is being considered, it requires size reduction and often pretreatment. For a project based on this material, a dedicated BMP test on the specific batch is essential, and the literature value should serve only for an indicative comparison with other lignocellulosic substrates.

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 = 0.039 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

  1. Ge, X.; Matsumoto, T.; Keith, L.; Li, Y. (2014). Biogas energy production from tropical biomass wastes by anaerobic digestion. Bioresource Technology 169, 38–44. DOI: 10.1016/j.biortech.2014.06.067 DOI

All sources of the site: bibliography.

Other substrates in the group “Wood and woody biomass”